Mattmvb
Joined: 29/03/08
Posts: 49
Loc: Birmingham, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#664235 - 05/10/08 10:37 PM
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Thanks to this thread I've altered my weekly routine. Previously I'd always test my
emergency lights and fire alarm on a tuesday morning; I've now added socket testing to
this list.
I've come up with a theory that may or may not be right, but if it
is completely wrong it can't do me any harm anyway. Basically, I reckon that terminal
screws in plugs and sockets in locations that are subjected to high sound levels must be
more likely to work loose over time because of the vibrations - you can also add in the
vibrations from the footfall of a couple of hundred excited people - and of course the
body fall of a couple of excited drunk people...
Please keep the safety advice
coming.
Cheers,
Matt
-------------------- One is too many, two is about right, but three can never, ever, be enough
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Nathan
Joined: 13/09/04
Posts: 1872
Loc: lincolnshire government experi...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Mattmvb]
#665127 - 08/10/08 04:48 AM
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Mattmvb,
more relevant is the usage: being regularly plugged/unplugged, thrown
into boxes/flightcases amd transported in vehicles with all the resultant periods of
vibration. This handling will affect virtually any screw termination after a period of
time -something that normal office mains extensions will not have to endure.
I
seal mains screw terminals with a blob of nail-varnish to combat this (my original
background is in electrical engineering and instrumentation and calibration adjustment
trims are always sealed in this manner after any change); this seems to prevent loosening.
I also check the earth integrity of my cable very regularly (the most
important electrical connection) and I visually check all my mains cables every time they
are unpacked for a gig and repacked at the end of the night Cables are a rig's weakest
link and safety and reputation are of paramount importance to any PA company.
get a mains tester and check your extension leads as you plug-in during set-up. buy a
beer for an electrician mate and get him to check all your cables once a year...
-------------------- planet nine
lincoln, uk.
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Mattmvb
Joined: 29/03/08
Posts: 49
Loc: Birmingham, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Nathan]
#665783 - 10/10/08 12:24 AM
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Quote Nathan:
Mattmvb,
I seal mains screw terminals with a blob of nail-varnish to combat this (my original
background is in electrical engineering and instrumentation and calibration adjustment
trims are always sealed in this manner after any change); this seems to prevent loosening.
Thanks for the
tip Nathan.
I've also learnt another lesson the hard way. To cut a long story
short I'm off to B&Q in the morning to buy some shatterproof plugs and 4-way adaptors.
Fortunately nobody came to any harm but it was quite worrying to see a guitarist lose his
balance whilst setting up, tread on a plug and watch half of it break off!
With
regard to the cable testing, I'm fortunate to be located next door to a large theatre so
no worries there - although my mains voltage can be a bit variable when they've got a big
show on!
Thanks,
Matt
-------------------- One is too many, two is about right, but three can never, ever, be enough
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Sheriton
Joined: 27/01/03
Posts: 1554
Loc: Leicester, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Mattmvb]
#665819 - 10/10/08 08:29 AM
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Quote Mattmvb:
To cut a long
story short I'm off to B&Q in the morning to buy some shatterproof plugs and 4-way
adaptors.
Rubber plugs &
sockets are your friend. They cost more, but can take far more abuse.
-------------------- There's nothing we can't face... Except for bunnies
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Nathan
Joined: 13/09/04
Posts: 1872
Loc: lincolnshire government experi...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Sheriton]
#666335 - 12/10/08 10:04 AM
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Duraplug and Permaplug are the brands to look for, you can get them both in the larger
B&Qs, but it might do you to buy from Canford as boxes of ten, etc will work out
cheaper.
if you can't find the above brands, look for plugs with
BS1363/A on them as the A means they comply to the more physically
robust spec.
-------------------- planet nine
lincoln, uk.
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Steven Montgomery
Joined: 06/06/06
Posts: 39
Loc: Northern Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#674267 - 02/11/08 09:53 PM
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You just gotta make sure that the pa and the amp are running of the same circuit. If your
not sure about the wiring of the room buy yourself a proper RCD and plug it into the wall,
and run everything from there. For most small things you should be grand, for bigger stuff
make sure you jump up to 16a or something of the sorts as soon as you come out of the
wall, and a wee distro wouldnt go a miss.
-------------------- Monty
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Eon
Joined: 11/05/09
Posts: 2
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#733859 - 11/05/09 04:41 PM
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I've just started as an house engineer at a rather small club and just last weekend the
guitarist started getting shocks, didn't think it was this big of a deal and will check
all the sockets right away.
But, I've got a question, there is a smoke machine
hooked on the same fuse as the backline and mixer, could this be a factor in shocks? It's
all metal and stands to the side of the stage.
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seablade
Joined: 21/11/04
Posts: 3769
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Eon]
#733866 - 11/05/09 04:54 PM
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Quote Eon:
But, I've got a
question, there is a smoke machine hooked on the same fuse as the backline and mixer,
could this be a factor in shocks? It's all metal and stands to the side of the stage.
Only if the guitarist is
touching it as well.
Seablade
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seablade
Joined: 21/11/04
Posts: 3769
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Re: Well, yeah, again, electric shocks from mics !!
[Re: seablade]
#733870 - 11/05/09 05:12 PM
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Actually if the guitar amp and fogger are plugged into the same outlet, and that outlet is
not grounded, then yes this could also be a problem.
But the end result is that
it is important for ALL equipment that shipped with a ground connection, be in fact
grounded.
Seablade
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Sheriton
Joined: 27/01/03
Posts: 1554
Loc: Leicester, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#733893 - 11/05/09 07:06 PM
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The last guitar amp that came to one of my venues: I could see it would fail its PAT
before I even got anywhere near it! The guitarist was busy stuffing the mains cable
further in to the plug as the outer insulation had been stripped back far too far and the
strain relief was obviously ineffectual. I opened the plug and found a 13A fuse instead of
the 5A that should have been in there for the size of mains cable. And the earth wire had
been cut. Not worked its way loose but cleanly cut.
I rewired it, did the rest
of the PAT and handed it back to him with an explanation of why it wouldn't kill him
now.
Lessons learnt: be VERY suspicious of guitar amps when it comes to
electrical safety.
-------------------- There's nothing we can't face... Except for bunnies
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Ian Savage
Joined: 16/12/07
Posts: 611
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#733954 - 11/05/09 10:46 PM
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Thanks for all this; I'm usually wireless live but our singer's been getting some nasty
buzzes of late both live and in the rehearsal room. Musy pick up some RCDs and a socket
tester as a matter of urgency.
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Nathan
Joined: 13/09/04
Posts: 1872
Loc: lincolnshire government experi...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Ian Savage]
#751239 - 09/07/09 07:43 AM
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This theme about singers and guitarists getting twitches from mics seems to be a recurring
endemic, so I thought I'd offer some advice.
If you're getting shocks off a mic
then don't just stuff a pop-shield over it, find out what's happening; either the mic is
live or you're greounding yourself on the mic because something else is.
check
that the earth wire is intact and connected in the plug to your PA amps and mixer, your
guitar amps and any mains leads and extension blocks that supply it.
Don't take
any excuses whatsoever from any guitarist who's removed an earth. None. reconnect of f***
off. Funerals are not as fun as gigs, even for Emo bands.
The only time that a
plug with no earth is ok is if the appliance is "double insulated" (class2) and carries
the square-inside-a-square symbol. No symbol and no earth? get someone to look at it
before you use it!
Never use any mains extension that doesn't have an earth
unless it is terminated in a two pin socket (like a lawnmower extension lead, see above
for class2) if it has a 13A three-pin socket, appliances that require an earth could be
plugged in and would not have their necessary earth (you'd be prosecuted if there was an
accident).
If you are getting shocks and you're not sure what's at fault, buy
or borrow a multimeter and put it on the mains (AC) setting -usu 250, 500, 1000V switch;
measure between the mic grille and a water pipe or sink top or earth pin on a 13A socket,
anything more than a couple of volts (high impedance floaty mains-hum pickup) is a problem
and needs investigating. Try it from the bridge or strings of the guitar and see if
there's any voltage. Generally anything above 50Vac will cause you a tingle when you put
your lips on an earthed mic grille. the most common reading if there is a compromised
earth is half normal mains voltage -about 120V. Sort it look at the earth in any mains,
IEC and extension leads.
It's always a good idea to have your own 30mA RCD
plug. Then you know if you touch 240V it will trip and protect you. Press the test button
regularly to make sure it trips when mains is on. Those mains plug testers with three
lights to show whether your earth is there and Live and Neutral are right-way-round are
good too -I check all venue supplies like this.
check your mains and extension
leads every time they come out of or go back into your bag/box. if there is any damage,
wires showing, scuffs, cracks in plugs, etc -sort it. PAT testers do that as the first
part of the test and won't even plug it into their tester if if fails the visual test
(you'll get charged your test fee as a fail, and a retest fee after they've fixed it).
Open up you plugs and make sure the wires are correctly terminated, looks tidy, shows no
sign of overheating, fraying, fuse is correct and the screws are all tight.
If
your gear looks tidy and looked over, most venues will not hassle you for PAT test certs
etc. They will raise eyebrows/refuse use of gear if it looks shot. PAT test once a year is
good practice for safety and hassle-free gigging, but must be supplemented by visual
checks. Look on the HSE website for charts of what to be looking for (HSE think the PAT
sticker movement has gone just a little to far and are quite keen for people to be
educated about appliance safety as an alternative to compulsory testing in many cases)
Remember ggiging can be hard on your electrical gear, safety is paramount and your
gear reliability is your gig reputation -look out for issues before they ruin your show or
hurt someone.
-------------------- planet nine
lincoln, uk.
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eggle5
Joined: 15/10/07
Posts: 52
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Nathan]
#757821 - 27/07/09 11:34 PM
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Quote Nathan:
This theme about
singers and guitarists getting twitches from mics seems to be a recurring endemic, so I
thought I'd offer some advice.
If you're getting shocks off a mic then don't
just stuff a pop-shield over it, find out what's happening; either the mic is live or
you're greounding yourself on the mic because something else is.
check that the
earth wire is intact and connected in the plug to your PA amps and mixer, your guitar amps
and any mains leads and extension blocks that supply it.
Don't take any excuses
whatsoever from any guitarist who's removed an earth. None. reconnect of f*** off.
Funerals are not as fun as gigs, even for Emo bands.
The only time that a plug
with no earth is ok is if the appliance is "double insulated" (class2) and carries the
square-inside-a-square symbol. No symbol and no earth? get someone to look at it before
you use it!
Never use any mains extension that doesn't have an earth unless it
is terminated in a two pin socket (like a lawnmower extension lead, see above for class2)
if it has a 13A three-pin socket, appliances that require an earth could be plugged in and
would not have their necessary earth (you'd be prosecuted if there was an accident).
If you are getting shocks and you're not sure what's at fault, buy or borrow a
multimeter and put it on the mains (AC) setting -usu 250, 500, 1000V switch; measure
between the mic grille and a water pipe or sink top or earth pin on a 13A socket, anything
more than a couple of volts (high impedance floaty mains-hum pickup) is a problem and
needs investigating. Try it from the bridge or strings of the guitar and see if there's
any voltage. Generally anything above 50Vac will cause you a tingle when you put your lips
on an earthed mic grille. the most common reading if there is a compromised earth is half
normal mains voltage -about 120V. Sort it look at the earth in any mains, IEC and
extension leads.
It's always a good idea to have your own 30mA RCD plug. Then
you know if you touch 240V it will trip and protect you. Press the test button regularly
to make sure it trips when mains is on. Those mains plug testers with three lights to show
whether your earth is there and Live and Neutral are right-way-round are good too -I check
all venue supplies like this.
check your mains and extension leads every time
they come out of or go back into your bag/box. if there is any damage, wires showing,
scuffs, cracks in plugs, etc -sort it. PAT testers do that as the first part of the test
and won't even plug it into their tester if if fails the visual test (you'll get charged
your test fee as a fail, and a retest fee after they've fixed it). Open up you plugs and
make sure the wires are correctly terminated, looks tidy, shows no sign of overheating,
fraying, fuse is correct and the screws are all tight.
If your gear looks tidy
and looked over, most venues will not hassle you for PAT test certs etc. They will raise
eyebrows/refuse use of gear if it looks shot. PAT test once a year is good practice for
safety and hassle-free gigging, but must be supplemented by visual checks. Look on the HSE
website for charts of what to be looking for (HSE think the PAT sticker movement has gone
just a little to far and are quite keen for people to be educated about appliance safety
as an alternative to compulsory testing in many cases)
Remember ggiging can be
hard on your electrical gear, safety is paramount and your gear reliability is your gig
reputation -look out for issues before they ruin your show or hurt someone.
Ur comments are well founded &
appreciated and have been copied onto our local music web scenes cos it's an on going
problem that never seems to go away!!!! The number of amps/mixers I've come across on
stage with the earth removed beggars belief. I've stopped bands playing because of this
and refused to do the sound for them. At the end of the day a 5 amp fuse versus an
electrocution - no contest but there are guys out there still doing this - I will not work
with them and tell them at the sound check. Get an RCD from B & Q - it ain't rocket
science & it's a cheaper way to save your life!!!!
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Stewart Newlands
Joined: 27/03/08
Posts: 11
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#759061 - 01/08/09 05:51 PM
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There is lots to read on the 7909 website
A website dedicated to Electrical
safety for Entertainment and related purposes
In particular: Bs7909:2008 The
Code of practice for temporary electrical systems for entertainment and related
purposes
Loads of links and advice on how to use electricity well.
http://www.7909.org.uk
Don't forget if you think a venue is unsafe apply to the local council for a licensing
review asking for a section 182 condition on electrical safety to be added!
Edited by Stewart Newlands (01/08/09 05:54 PM)
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IvanSC
Joined: 08/03/05
Posts: 7760
Loc: UK France & USA depending on t...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#759147 - 02/08/09 07:33 AM
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Was talking to My Mate Ted last night at a party & he told me the story of a recent
near disaster he experienced.
They use a tester etc and normally have no probs
with mains. They were playing an outdoor gig and some clown had mis-wired the three
phase supply so that two phases were hooked up to phase and neutral, givinbg a potential
of 460 volts across the supply.
Ted said his amp had never sounded so good for
the first set, then all of a sudden everything was smoking and he was flopping around like
a beached herring, still holding the offending (lethal) guitar lead. Fortunately the bass
player put his foot on ted`s hand holding the lead and got him off it, but the backline
was fried and poor old Ted was in a bad way for some time after.
And of course
he and a mate have now gone into business making this cool little box that measures the
potential between ALL connections (not just phase and earth and neutral & earth)and
shuts the supply down if anything exceeds 260 volts. So far three PA hire companies
have bought and I suspect he will get a lot of other customers. Around £100, which
is way cheaper than the next available thing at about £400
-------------------- Me? But I`m such a loveable old bugger!
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turbodave
Joined: 25/04/08
Posts: 2105
Loc: derbyshire uk
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#759158 - 02/08/09 09:07 AM
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Hi Ivan, so do I google "My mate Ted.co .uk" or will you spill the beans?Dave
-------------------- My head hurts!
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adamb1026
Joined: 05/10/09
Posts: 60
Loc: Belfast, N.Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#776231 - 05/10/09 09:54 PM
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This has happened on a number of occasions with our band most recently on Saturday night.
Our lead vocalist was receiving shocks on his microphone. The vocal is the only thing that
goes into the mixer since it was such a small venue and we don't own any bass bins yet. The mixing desk and power amp was plugged into a Surge Protected 4 way adapter
into what looked like a slightly dodgy plug, but we have played there on many occasions
and this was the first time this happened. We then just plugged in the mixer
into the plug and it worked fine. Our gear has been lugged in and out of vans
and cars for nearly 7 years now, with updates and changes of course, so I can see an
aspect of that affecting things, but the mixing desk is usually kept in good nick. Just a few quick questions, because this has been plaguing us for a while, and
myself. 1. Are surge protected 4 way plugs recommended? I have heard rumors
they are not good for powering amps etc. So just to confirm before i go out and buy some
 2. Is using many separate wall sockets the best method to combat electrical
shocks?
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Mike Stranks
active member
Joined: 03/01/03
Posts: 3063
Loc: Oxford, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#776313 - 06/10/09 08:44 AM
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Quote adamb1026:
This has
happened on a number of occasions with our band most recently on Saturday night. Our lead
vocalist was receiving shocks on his microphone. The vocal is the only thing that goes
into the mixer since it was such a small venue and we don't own any bass bins yet.
The mixing desk and power amp was plugged into a Surge Protected 4 way adapter
into what looked like a slightly dodgy plug, but we have played there on many occasions
and this was the first time this happened.
We then just plugged in the mixer
into the plug and it worked fine.
Our gear has been lugged in and out of vans
and cars for nearly 7 years now, with updates and changes of course, so I can see an
aspect of that affecting things, but the mixing desk is usually kept in good nick.
Just a few quick questions, because this has been plaguing us for a while, and
myself.
1. Are surge protected 4 way plugs recommended? I have heard rumors
they are not good for powering amps etc. So just to confirm before i go out and buy some

2. Is using many separate wall sockets the best method to combat electrical
shocks?
Surge protection
will not protect against dodgy earths - which is almost certainly what was happening
here.
I suggest you get yourself a socket tester - you can get them from
Maplins - which will let you see if the wiring in the socket is as it should be. Any
problems, then don't use that socket and tell the venue management that they have a
serious problem which needs fixing pronto.
But that's not enough. Always
connect to sockets using an RCD current dumper - widely available from DIY multistores.
And if you have several mains extensions daisy-chaining then put an RCD on each link. RCDs
only cost a few pounds and could save someone's life.
There's no advantage in
connecting to multiple wall sockets as long as you're not overloading one socket. In fact,
using multiple sockets raises the possibilities of introducing ground/earth loops.
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Sheriton
Joined: 27/01/03
Posts: 1554
Loc: Leicester, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#776333 - 06/10/09 09:35 AM
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Quote adamb1026:
This has
happened on a number of occasions with our band most recently on Saturday night. Our lead
vocalist was receiving shocks on his microphone. The vocal is the only thing that goes
into the mixer since it was such a small venue and we don't own any bass bins yet.
Does your lead vocalist
play guitar?
The body of the microphone will be connected to the ground /
earth of the mixing desk. If the mic body was at a potential that would cause shocks, it's
likely that the case of the mixer would be at this same potential. Did anybody notice any
tingles when touching the mixer?
In order to get a shock, you have to be
touching two things at different potentials at the same time. The mic is one of those
things; to be fair to it, the mic is usually not the culprit as it is usually at ground
potential.
99% of the time, the problem is with a singing guitarist's amp.
Despite the title of this thread, the mic is very rarely the cause.
-------------------- There's nothing we can't face... Except for bunnies
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adamb1026
Joined: 05/10/09
Posts: 60
Loc: Belfast, N.Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Sheriton]
#776356 - 06/10/09 10:55 AM
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Quote Sheriton:
Quote adamb1026:
This has
happened on a number of occasions with our band most recently on Saturday night. Our lead
vocalist was receiving shocks on his microphone. The vocal is the only thing that goes
into the mixer since it was such a small venue and we don't own any bass bins yet.
Does your lead vocalist
play guitar?
The body of the microphone will be connected to the ground /
earth of the mixing desk. If the mic body was at a potential that would cause shocks, it's
likely that the case of the mixer would be at this same potential. Did anybody notice any
tingles when touching the mixer?
In order to get a shock, you have to be
touching two things at different potentials at the same time. The mic is one of those
things; to be fair to it, the mic is usually not the culprit as it is usually at ground
potential.
99% of the time, the problem is with a singing guitarist's amp.
Despite the title of this thread, the mic is very rarely the cause.
Thanks Mike, will use your advice
Also, do you have any links to where I could buy a RCD damper? I've just been looking on
maplins and cant seem to find one.
Thanks again
Sorry,
should have been more specific, he was receiving shocks to his lips rather than the
casing. I don't think he received any shocks from the desk.
And yes he does
play guitar . Out of my ignorance, how does his amp become the problem?
Some
of the venues we play really don't accommodate bands well. They just find an empty space
and tell us to setup there. Since the smoking ban has come into our country, in one venue,
we basically play beside the door to where people have to get outside. We used to take the
whole area, but now since we are squeezed to one side, my bass head has almost become a
weapon lol
Edited by adamb1026 (06/10/09 10:56 AM)
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Sheriton
Joined: 27/01/03
Posts: 1554
Loc: Leicester, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#776360 - 06/10/09 11:14 AM
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Quote adamb1026:
Also, do
you have any links to where I could buy a RCD damper? I've just been looking on maplins
and cant seem to find one.
Not sure where the word damper came from but it's this kind of
thing that you're after. I can't vouch for that particular model as I've never used one
but any DIY store will sell you an RCD also.
Quote adamb1026:
And yes he does play guitar . Out of my
ignorance, how does his amp become the problem?
A lot of misguided guitarists cut the mains protective earth in
their amp, believing it to be the way to eradicate hum from their rig. Have a read right
through this thread for more details. I know it's long, but it may just save someone's
life. Seriously. Far too many guitarists have been killed through this stupidity. Get all
of your kit PAT tested regularly if you don't already do so. That will show up any
potentially dangerous faults like a lifted earth. And if your guitarist has
disconnected the earth, beat him around the head with the amp until he sees sense. There
is never EVER any reason for doing so. Under any circumstances. EVER.
-------------------- There's nothing we can't face... Except for bunnies
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adamb1026
Joined: 05/10/09
Posts: 60
Loc: Belfast, N.Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#776367 - 06/10/09 11:24 AM
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I dont think he has cut the earth, but I'll check it out in any case and give him a good
smack if he has.
Thanks very much for all of your help.
Must go
for a walk down to Maplins
Edited by adamb1026 (06/10/09 11:25 AM)
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seablade
Joined: 21/11/04
Posts: 3769
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#776418 - 06/10/09 12:59 PM
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Quote adamb1026:
I dont think he
has cut the earth, but I'll check it out in any case and give him a good smack if he
has.
A bad socket can cause a
similar effect. Pretty much if the ground is disconnected ANYWHERE in the power chain,
this NEEDS to be fixed. No exceptions. This is why people are suggesting the socket
tester, as it allows you to quickly and easily see if a socket is good, never assume it
is.
Seablade
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Mike Stranks
active member
Joined: 03/01/03
Posts: 3063
Loc: Oxford, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#776424 - 06/10/09 01:17 PM
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If he's getting shocks to his lips, there's a possibility that it was static electricity!
(NB. That doesn't mean you can ignore all the other stuff we've written!  ) I was once very agressively berated by a singing guitarist when he got a lip-shock. I
knew all the gear was OK, but checked it anyway - no problems found, all earths good.
Eventually I tracked it down to him wearing some synthetic materials and some
synthetic-soled trainers. He was his own little Van der Graff Generator and then earthed
himself through the mic capsule basket and its connections. That's not to take away from
the static shock you get though; it happened to me once and it ain't funny!
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dmills
Joined: 25/08/06
Posts: 2130
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#776568 - 06/10/09 09:13 PM
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Quote:
1. Are surge
protected 4 way plugs recommended? I have heard rumors they are not good for powering amps
etc. So just to confirm before i go out and buy some
Not particularly, at best the protection is
marginal, they often fail silently and they can contaminate the power ground (which really
shouldn't matter, but often does, particularly with unbalanced gear).
They
only do what any competent power supply designer should be doing anyway.
Quote:
2. Is using many
separate wall sockets the best method to combat electrical shocks?
Nope, using a few sockets that you have tested and
know to be correctly wired and earthed, and keeping all your gear in good repair is the
best way to avoid shocks, and RCDs are (while not foolproof) a good way to increase your
chances of surviving one.
A shock should be an indication that something
(several things) has gone badly wrong, and should always be a signal to stop and fault
find then fix whatever the problem is (And then review your maintenance, it should never
have gotten that far).
Sorry, but IMHO a shock is almost always an indication
that someone has screwed up, as it really should require at least 2 faults to cause one.
Regards, Dan.
-------------------- Audiophiles use phono leads because they are unbalanced people!
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adamb1026
Joined: 05/10/09
Posts: 60
Loc: Belfast, N.Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Mike Stranks]
#777113 - 08/10/09 12:19 PM
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Quote Mike Charles:
If he's
getting shocks to his lips, there's a possibility that it was static electricity! (NB.
That doesn't mean you can ignore all the other stuff we've written! )
lol well it has happened on a
few occasions, so through reading this topic, I can pretty much confirm it is the plugs
, but I
will keep that in mind next time it happens.
Thanks dmills on the advice
especially about surge protectors.
We do have an large amount of gear.
Particularly our lead guitarist has 8 pedals through a Behringer 12 set pedal board, which
I thought was maybe could be a concern for future electric problems. Again excuse my
ignorance if it isn't.
I think I'm going to persuade him and invest in a hard
case for the mixer and power amp after telling him about this and to genuinely keep his
mixer in good nick .
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Nathan
Joined: 13/09/04
Posts: 1872
Loc: lincolnshire government experi...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#777579 - 09/10/09 11:30 PM
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if this mic-grille shock has happened multiple times in different venues, it suggests that
the problem might be a fault of your band's gear somewhere (the common factor).
If you have a multimeter, set it to its 250V, 500V or 1000V AC setting and measure
between the mic grille and a radiator or water pipe) If there's more that a couple of
Volts then you could have a mains earth-issue in your PA or mixer supply.
If
that's normal, but measuring between your guitarist's bridge or strings and the
radiator/pipe gives you a reading, then the issue is with the guitar amp or mains
plug/cable supplying it. What you're looking for is voltage on something that should be
earthed.
Post or PM me if you need further help. Nathan.
>
-------------------- planet nine
lincoln, uk.
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adamb1026
Joined: 05/10/09
Posts: 60
Loc: Belfast, N.Ireland
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#778709 - 13/10/09 06:52 PM
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That's great Nathan thanks.
My dad should have a multimeter lying about in the
garage somewhere who is a qualified electrician, so I can tell him about your technique
and he can guide me a bit further as well.
Appreciate the help.
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Nathan
Joined: 13/09/04
Posts: 1872
Loc: lincolnshire government experi...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: adamb1026]
#779694 - 17/10/09 10:36 AM
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establish that there is an issue between bridge and mic grille first by measuring directly
between them, if it reads about 120V approach with caution! This will rule out a static
electricity issue, then measure to each from the water pipe. Bear in mind that this trick
can also dig out problems with installed wiring earths, and also that not all central
heating systems are earthed (although they should be bonded).
I usually find
that its an earth problem in a mains cable leading to the guitar amp, but this method has
traced problems to loose earths in extension leads supplying the PA mixer too.
>
-------------------- planet nine
lincoln, uk.
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Nathan]
#779720 - 17/10/09 11:32 AM
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Yes, you need to be very logical and thorough when trying to track down a potential
satefty earth problem like this.
There are lots of earth interconnections
between the wall socket and the guitar, and every single one has to be good to be safe...
so work through carefully and logically fromt he wall socket.
Start with a
mains plug tester, as recommended above to check the wall socket(s) and do that at every
single venue you use every single time you use it. I lost count years ago of how many tims
I've found duff, unsafe sockets in public venues.
If the socket is safe and
properly earth bonded, then work through all your mains extension boards and extension
cables. The first check -- and one you should do everytime you pack and unpack you gear is
a visual one, looking for cracks, cuts or crushes to the cable or any damage to the plugs
of sockets -- any sign of physical damage requires careful investigation before use.
You can test the extension cables and boards with a multimeter but a quick and
easy way is to use the mains socket tester again by plugging the extension cable of
distribution board into the wall socket and then plugging the tester into each socket on
the board or cable to check they are all okay. It is possible for individual sockets in
extension boards to fail too...
If all the mains distribution stuff tests fine,
then you'll need to move on to the IEC mains cables or the equipment itself if it uses
captive mains leads. This is where you'll need to use a multimeter with a resistance or
continuity mode. Don't plug the IEC leads into the mains -- instead put one probe onto the
large mains plug earth pin and the other into the offset central earth receptacle on the
IEC socket. You should get a reading of zero ohms or 100% continuity.
If it's a
captive cable, then check between the mains plug earth pin and the metalwork on the
equipment -- unless the label has the double-insulated symbol (a box within a box), in
which case you won't get any continuity at all, by design.
Static shocks can be
unsettling but are rarely any real problem and perversly do indicate that the system is
probably properly earthed!
One way to determine whether you have a serious
safety earth problem or just static shocks is to find out if the shock happens constantly
or just briefly now and again.
A safety earth problem will mean that every
single time someone bridges between something properly earthed (usually the mic) and the
faulty part of the system (usually the guitar amp), they will get a shock (or, hopefully,
trip the RCD!) and that the shock continues for as long as they are in contact (or until
the RCD trips).
If it's a static shock, the first time they touch anything
earthed they will discharge themselves and feel the brief moment of shock but thereafter
they won't feel anything while they remain in contact. And if they touch it again a few
moments later they won't feel a second shock either.
Only after they've
shuffled around on the carpet or danced about to recharge their clothes will they build up
their own static potential enough to feel a shock when discharging again through something
earthed.
Hugh
-------------------- Technical Editor, Sound On Sound
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the muppet
Joined: 27/08/04
Posts: 1010
Loc: with my head stuck up my a£se...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Hugh Robjohns]
#796104 - 14/12/09 03:27 PM
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Hugh,
As this topic comes up time and time again, and as a lot of us return to
the same venues, would it be with our rights or the rules of the forum to start "naming
and shaming" the venues that have dodgy supplies and such like.
I've been
touring now for quite some time and there are venues out there that I'm always very
dubious about pluging even my phone charger into, but those where I have even refused to
plug into the heavier mains supplies.
One, which shall for the mean time remain
as Venue X had 2x 32a single ceeforms on each side of the stage, mounted on the floor.
Both were live-neutral reversed and one was so badly damaged that I couldn't even plug my
rack in (we have EMO distro in all our racks which has those handy neon indicators)
When speaking to the in-house electrician about why I wasn't about to plug my gear
in, he said "Everybody uses them, it's ok for them, it can be ok for you!"
This
isn't just a small pub somewhere, this is a major national venue. We shouldn't be taking
this kind of attitude and I refuse to go back and have mentioned it to the relevant
authorities, but I think as most of us know, this can't happen again.
PM me if
you want to chat about how we do this
Cheers
Ben
-------------------- The early bird may catch the worm, but it's the second mouse that gets the cheese!
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Well, yeah, again, electric shocks from mics !!
[Re: the muppet]
#796132 - 14/12/09 05:31 PM
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I can certainly understand your frustration, Ben, but I think I'll need to take some
advice before allowing a name and shame thread... tempting though it would be.
Leave it with me for a few days please.
Hugh
-------------------- Technical Editor, Sound On Sound
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TheChorltonWheelie
Joined: 22/09/09
Posts: 867
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Mike Stranks]
#796142 - 14/12/09 06:05 PM
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Quote Mike Charles:
If he's
getting shocks to his lips, there's a possibility that it was static electricity! (NB.
I'll tell you now, I am very
susceptible to static - I even have to be careful when I get out the car, by earthing
myself first, and I'm not kidding either. I regularly get shocks from mic's, and all my
kit properly earthed/pat tested (which I did as a result of having read a thread like this
years ago).
Some people are just unlucky.
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the muppet
Joined: 27/08/04
Posts: 1010
Loc: with my head stuck up my a£se...
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Hugh Robjohns]
#796190 - 14/12/09 10:46 PM
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Quote Hugh Robjohns:
I can
certainly understand your frustration, Ben, but I think I'll need to take some advice
before allowing a name and shame thread... tempting though it would be.
Leave
it with me for a few days please.
Hugh
Of course!!
I will say that 99% of venues we go to are
spot on and I wouldn't have a word said against them.
I understand it's very
much a case of the venue could be the safest place to plug into but a bands gear is shot
to bits, and vice versa.
It just seems to me that so many legislations are out
there now to stop this sort of thing happening, it happens on such a regular basis.
This may be slightly off topic, but when, in a time when health and safety is
killing our industry, is a lack of health and safety potentially risking our lives?
I'm sorry if I seem to have come across all stroppy about this, but judging by the
number of posts here, it's obviously a major concern
Ben
-------------------- The early bird may catch the worm, but it's the second mouse that gets the cheese!
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18390
Loc: Worcestershire
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Re: Well, yeah, again, electric shocks from mics !!
[Re: the muppet]
#796195 - 14/12/09 10:59 PM
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Quote the muppet:
As this topic
comes up time and time again, and as a lot of us return to the same venues, would it be
with our rights or the rules of the forum to start "naming and shaming" the venues that
have dodgy supplies and such like.
I've discussed it with Ian, and as you probably suspected, the word is no. It's
just too risky if someone doesn't get their facts straight (accidentally or even
deliberately), or the venue improves and the thread isn't updated. It would leave SOS open
to being sued, and that really wouldn't be a good idea.
So, sorry. But no. I
think the best course of action would simply be to bring any venue with poorly maintained
electrical supplies to the attention of the appropriate regulatory bodies -- the local
council or the HSE.
Hugh
-------------------- Technical Editor, Sound On Sound
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feline1
active member
Joined: 23/06/03
Posts: 3651
Loc: Brighton, UK
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Re: Well, yeah, again, electric shocks from mics !!
[Re: Hugh Robjohns]
#796271 - 15/12/09 11:37 AM
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Quote Hugh Robjohns:
Quote the muppet:
As this topic
comes up time and time again, and as a lot of us return to the same venues, would it be
with our rights or the rules of the forum to start "naming and shaming" the venues that
have dodgy supplies and such like.
I've discussed it with Ian, and as you probably suspected, the word is no. It's
just too risky if someone doesn't get their facts straight (accidentally or even
deliberately), or the venue improves and the thread isn't updated. It would leave SOS open
to being sued, and that really wouldn't be a good idea.
So, sorry. But no. I
think the best course of action would simply be to bring any venue with poorly maintained
electrical supplies to the attention of the appropriate regulatory bodies -- the local
council or the HSE.
Hugh
Indeed - it's not a magazine's job to police electrical safety in the field. It would be about like witnessing an accident and phoning your local newspaper about it
instead of dialling 999 for an ambulance. If someone does report electrical problems
promptly to the local council or HSE, then those bodies should fairly swiftly see that
they are dealt with in any case, so the problem should not exist for very much longer.
-------------------- ~~~ A weasel hath not such a deal of spleen as you are tossed with! www.feline1.co.uk ~~~
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chris...
active member
Joined: 12/03/03
Posts: 4152
Loc: Glasgow
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Re: Well, yeah, again, electric shocks from mics !!
[Re: ghc]
#800134 - 02/01/10 05:06 PM
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OK, so whilst rehearsing today, bass player experienced mild shock from mic. So we
plugged the socket tester into the "garden" mains extension lead his bass combo
was plugged into. Earth missing. Opened up the extension lead's plug and socket,
expecting to find a loose/damaged earth connection. But no...
It was 2-core
mains cable. Never had an of earth any kind (!)
Is this sort of thing common ? Are all lawnmowers double-insulated, or something ?
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dmills
Joined: 25/08/06
Posts: 2130
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Re: Well, yeah, again, electric shocks from mics !!
[Re: chris...]
#800150 - 02/01/10 06:20 PM
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Quote Chris Edwards:
It was
2-core mains cable. Never had an of earth any kind (!)  Is
this sort of thing common ? Are all lawnmowers double-insulated, or something ?
Basically, yes!
There are
electrical safety "issues" with taking the earth outside the building due to the way most
domestic supplies in the UK are earthed.
Due to this most garden appliances are
double insulated and most have 2 core cables. I am however shocked (SORRY!) to discover
that an extension cable (presumably with a 13A socket on the end) is being supplied wired
with 2 core.
You do find 2 core cables made for garden use with lawnmower
connectors on them (which are inherently 2 pin), and I hope that lethal extension came
from some numpty modifying such a lead rather then being a commercial product.
When powering outdoor gigs from a building supply which is suspected to be TN-C-S or
(PME) connected (the normal way these days), the safest way to do it is to bring out the
live and neutral and derive a TT supply locally (with an RCD and local earth connection)
or to use an isolating transformer (with local spike) and derive a TN-S supply with your
own transformer.
Both require some thought and some specialist tools to test
and verify for safety, and the issue is largely ignored by a lot of folks, but there is a
right way and a wrong way to do these things.....
Regards, Dan.
-------------------- Audiophiles use phono leads because they are unbalanced people!
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chris...
active member
Joined: 12/03/03
Posts: 4152
Loc: Glasgow
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Re: Well, yeah, again, electric shocks from mics !!
[Re: dmills]
#800157 - 02/01/10 06:42 PM
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Quote dmills:
most garden
appliances are double insulated and most have 2 core cables.
Ah, right.
Quote:
I am however shocked
(SORRY!) to discover that an extension cable (presumably with a 13A socket on the end) is
being supplied wired with 2 core.
You do find 2 core cables made for garden
use with lawnmower connectors on them (which are inherently 2 pin), and I hope that lethal
extension came from some numpty modifying such a lead rather then being a commercial
product.
I'm not familiar
with this 2-pin lawnmower connector. My own tiny flymo simply has a regular 3-pin mains
plug.
Anyway, back to the extension lead in question. Yes, it had a 13A
3-pin mains plug at one end, and a 3-pin socket on the other. The bass player remembers
buying it from B&Q some years ago - ie. not modified by a numpty...
This experience made me wonder if such extensions (2-core mains cable, with 3-pin
plug/socket) are common in the gardening fraternity - with the understanding they're only
to be used with double-insulated kit.
But I take it you're confirming this
is not the case ?
Ta
PS - incase I wasn't very clear,
this was an indoor rehearsal. The "garden" extension simply came to hand easily.
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dmills
Joined: 25/08/06
Posts: 2130
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Re: Well, yeah, again, electric shocks from mics !!
[Re: chris...]
#800159 - 02/01/10 06:56 PM
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Quote Chris Edwards:
But I
take it you're confirming this is not the case ?
Indeed, anything with a 13A socket on it
(with very few specialist exceptions (of which an extension lead is never one)), should
have a earth connection.
This is the sort of thing that begets two core cables
for garden use: http://www.maplin.co.uk/Module.aspx?moduleno=13176
Note
that a two core cable with a 13A PLUG on one end and a female one of these on the other is
totally standard (and safe) as a cable for things like some flymo lawnmowers. What you
should never see is such a cable with a SOCKET on it.
I would suspect someone
of modifying a lawnmower cable, but I suppose anything is possible.
Regards,
Dan.
-------------------- Audiophiles use phono leads because they are unbalanced people!
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