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Rack mains

Postby WADEAL » Wed Mar 27, 2013 11:28 pm

I have a 4u effects rack and at the back I have a 6 way rackmount mains board. The mains board has a typical 13 amp plug and 3m of cable trailing. The plug rattles about in the back of the rack and has a tendency to dislodge jacks in transit. I can't simply plug it into the board, as all of the sockets are in use by effects and wireless units.

Simple question. Can I safely cut the cord to about 3 or 4 inches in length and replace the plug with one of those male IEC kettle type adaptors, so that I can then wire up and plug in a much longer lead with a male adaptor that can sit safely in my box of leads?
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Re: Rack mains

Postby Exalted Wombat » Thu Mar 28, 2013 12:11 am

WADEAL wrote:I have a 4u effects rack and at the back I have a 6 way rackmount mains board. The mains board has a typical 13 amp plug and 3m of cable trailing. The plug rattles about in the back of the rack and has a tendency to dislodge jacks in transit. I can't simply plug it into the board, as all of the sockets are in use by effects and wireless units.

Simple question. Can I safely cut the cord to about 3 or 4 inches in length and replace the plug with one of those male IEC kettle type adaptors, so that I can then wire up and plug in a much longer lead with a male adaptor that can sit safely in my box of leads?

I suppose so. I can't see the different maximum ratings (10 amps for the IEC connector) being an issue in this case. I don't imagine you had a 13 amp fuse in the existing 13 amp plug anyway?

It gives you an additional point of potential failure though. Is it beyond your ingenuity to construct a method of securing or parking the mains plug within the rack?
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Re: Rack mains

Postby Hugh Robjohns » Thu Mar 28, 2013 11:05 am

WADEAL wrote:Can I safely cut the cord to about 3 or 4 inches in length and replace the plug with one of those male IEC kettle type adaptors


It would be a perfectly acceptable solution... (bearing in mind the 10A max rating for IEC connectors -- althogh tehre are some 6A versions around too!) ... but whether you can do it safely or not, I couldn't say!

If you are confident of how to do it safely, then sure... but messing with mains connectors obviously has potentially lethal outcomes so only do this if you are 100% confident of your abilities, have the requisite skills and tools, and understand the risks. In practice, it really isn't rocket science but we must be careful and issue the appropriate warnings!

And it isn't a 'kettle type adapter' -- 'kettle plugs' are actually known as C15 plugs within the IEC 60320 connector family. They have a slot along the lower edge that mates with a corresponding ridge in the C16 chassis socket and are rated for high temperature applications like kettles. The ridge prevents the use of standard C13 plugs which is what we typically use with audio equipment. We don't use 'kettle plugs'

The in-line or chassis connector you need is a C14-type.

However, it might also be worth considering using a more secure, latching mains connector, like the excellent Neutrik Powercon. You could either use a cable mounting inlet type (NAC3MX), or fit a chassis inlet (NAC3MPX) to the flightcase itself somewhere (you'll need to protect the back of the connector with insulation in some way of course). The outlet connector to go on the mains power supply cable is an NAC3FX.

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Re: Rack mains

Postby shufflebeat » Thu Mar 28, 2013 12:16 pm

However, it might also be worth considering using a more secure, latching mains connector, like the excellent Neutrik Powercon.


Slightly double edged one, this. Apart from the technical reasons why this is an excellent suggestion it also avoids the possibility of someone else pocketing it as theirs as is common. However, if and when yours does go walkabout it is not always easy to get your hand on another one in a hurry.

You could always just fix a piece of string or Velcro strap the inside of the case and tie the bugger down.
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Re: Rack mains

Postby Hugh Robjohns » Thu Mar 28, 2013 12:33 pm

shufflebeat wrote: However, if and when yours does go walkabout it is not always easy to get your hand on another one in a hurry.


That's a very fair point, and I've often heard the same said about Speakon cables too... and that's why I suggested considering converting to Powercon rather than an outright recommendation as a solution.

Obviously, it would be unwise to have only one Powercon mains lead in the rig, and it might make more sense if you decide to adopt this connector format throughout the system (if budget and practicality allow).

IECs have become ubiquitous and that has the advantage of low cost and convenience, obviously, but for live sound work the lack of latching security is often a serious concern, as is the variation of fuse values and cable current rating found in 'standard' IEC mains cables, and the ease with which IEC cables go walkabout.

I do like Powercons -- they offer a very well designed solution that is technically far superior to IECs -- but I can also recognise the expense and 'non-standard' issues. However, by continuing to encourage their use perhaps one day they will become as ubiquitous as the horrible IEC! It's working for Speakons

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Re: Rack mains

Postby Hugh Robjohns » Thu Mar 28, 2013 12:37 pm

shufflebeat wrote:You could always just fix a piece of string or Velcro strap the inside of the case and tie the bugger down.

The simplest solutions are always the best!

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Re: Rack mains

Postby Exalted Wombat » Thu Mar 28, 2013 4:38 pm

Hugh Robjohns wrote:However, it might also be worth considering using a more secure, latching mains connector, like the excellent Neutrik Powercon. You could either use a cable mounting inlet type (NAC3MX), or fit a chassis inlet (NAC3MPX) to the flightcase itself somewhere (you'll need to protect the back of the connector with insulation in some way of course). The outlet connector to go on the mains power supply cable is an NAC3FX.

H

I strongly advise against making yourself reliant on one non:-) standard cable! You can always scrounge an IEC mains cable or a 13amp extension.
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Re: Rack mains

Postby ef37a » Fri Mar 29, 2013 8:31 am

http://www.comms-express.com/products/iec-lock-c13-female-ie...

I did not know there was a latching version of the IEC mains connector until a couple of weeks ago when I read about it in a CPC flyer but cannot now find them on their site!

You can also get IEC conns' in white which might make it more visible if it walks off!

I too have a horror of "odd", hard to source connectors having growed up with 7 different mains outlets!
(and "horrible" to you they might be Hugh but they are infinitely prefferable to fixed mains leads! The only other viable alternative)
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Re: Rack mains

Postby Hugh Robjohns » Fri Mar 29, 2013 10:49 am

ef37a wrote: I did not know there was a latching version of the IEC mains connector

Yes, it's been around for several years now. I first came across it in the CANFORD catalogue five or more years ago.

They do latch very securely in standard sockets but it's not an ideal solution for me.... but then there probably isn't a perfect solution anyway! There are certainly many applications where a locking IEC is a good solution, and I do use them on racked equipment where there is no routine requirement to disconnect the internal mains distribution. However:

1. There are no DIY re-wirable versions -- you have to buy them moulded on to pre-cut cables or extensions.

2. You can't release them in high-density power distribution racks without a special tool.

3. Depending on the orientation of the IEC inlet, the fact that it's a latching connector isn't obvious as the release button can be hidden underneath.

4. Few people expect to see a latching IEC connector and so just keep tugging harder and harder at the thing until something breaks! (yes, it has happened!)

So where you have equipment with fixed wiring where a locking IEC is a good idea to prevent accidental disconnection (which is really only in portable, flight-cased equipment or in OB trucks), locking IECs are worth considering. However, for cable extensions and power inlets, etc I don't use them at all -- I prefer the powercon (or the blue 60309 plugs). At least the Powercon connector and 60309 are strange enough to most people that they ask how to disconnect them, instead of just yanking hard on a plug they expect to release easily!

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Re: Rack mains

Postby ef37a » Fri Mar 29, 2013 11:18 am

Hugh Robjohns wrote:
ef37a wrote: I did not know there was a latching version of the IEC mains connector

Yes, it's been around for several years now. I first came across it in the CANFORD catalogue five or more years ago.

They do latch very securely in standard sockets but it's not an ideal solution for me.... but then there probably isn't a perfect solution anyway! There are certainly many applications where a locking IEC is a good solution, and I do use them on racked equipment where there is no routine requirement to disconnect the internal mains distribution. However:

1. There are no DIY re-wirable versions -- you have to buy them moulded on to pre-cut cables or extensions.

2. You can't release them in high-density power distribution racks without a special tool.

3. Depending on the orientation of the IEC inlet, the fact that it's a latching connector isn't obvious as the release button can be hidden underneath.

4. Few people expect to see a latching IEC connector and so just keep tugging harder and harder at the thing until something breaks! (yes, it has happened!)

So where you have equipment with fixed wiring where a locking IEC is a good idea to prevent accidental disconnection (which is really only in portable, flight-cased equipment or in OB trucks), locking IECs are worth considering. However, for cable extensions and power inlets, etc I don't use them at all -- I prefer the powercon (or the blue 60309 plugs). At least the Powercon connector and 60309 are strange enough to most people that they ask how to disconnect them, instead of just yanking hard on a plug they expect to release easily!

H
O...K. The white ones are rewirable tho! D.
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Re: Rack mains

Postby Folderol » Fri Mar 29, 2013 6:51 pm

At the risk of causing a riot, one thing I hate to see (with a few notable exceptions) is any from of captive electrical connector.

I want ones with a straight profile that will pull out cleanly if snagged, and I speak from bitter experience. The right angle entry to 13A plugs are a case in point. They tend to be quite brittle (as are the wall sockets) and I've lost count of the number of times in the 'old' days I've gone to a house to find the TV plug held together with selotape and the wires hanging out the back. To say nothing of wall sockets with lumps missing from around the live or neutral holes - or the earth pin stuck in place.

A lot of machinery for magazine production is in modular form. These are quite heavy lumps - trundleable rather than portable - and are daisy-chained to perform the required sequence of glue/stitch/crease/cut. The cables usually carry 3 phase power along with a bunch of control wires. Traditionally all the wires are the same colour (usually black). These have nice solid, latching, 64 way 'Harting' connectors. The machine operators have a habit of forgetting to unplug them before moving the modules, which can develop quite a bit of momentum before the slack is taken up.

Need I say more?
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Re: Rack mains

Postby Hugh Robjohns » Fri Mar 29, 2013 8:12 pm

ef37a wrote: O...K. The white ones are rewirable tho! D.

There are lots of rewirable IEC plugs, but I've not found any rewirable locking ones. Are these white ones the locking type ?

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Re: Rack mains

Postby Hugh Robjohns » Fri Mar 29, 2013 8:15 pm

Folderol wrote: Need I say more?


Most jobs require a certain level of competence!

Seriously, though, it is important that we always place and arrange cables to remove any trip or snag risks.
Like you, I don't advocate using locking connectors everywhere, only where there is a risk of them falling out through vibration or shocks etc.

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Re: Rack mains

Postby ef37a » Fri Mar 29, 2013 9:20 pm

Hugh,No I don't think the white ones are locking but are "rarer and visible".

Will. Could you not use chain or steel cables to take the strain off the electrics?

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Re: Rack mains

Postby Folderol » Fri Mar 29, 2013 10:52 pm

Evenin' Dave
Unfortunately this is not practical. It is manufacturer's spec. kit and the customers would not pay for modifications. Besides, the machine operators are not highly paid so have a commensurate interest in the well being of the equipment

P.S.
They'd only detach the wire/chain anyway.
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