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Earth Bonding in a PDU

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Re: Earth Bonding in a PDU

Postby Hugh Robjohns » Thu Jan 24, 2019 12:33 pm

Wonks wrote:You also have the added complication that a lot of legacy or badly designed musical rack gear wants to remain isolated from the rack earth to avoid ground loops, so isolating washers are fitted.

Fixed that for you! :lol:

I can't remember the last time I had to resort to using isolating washers on rack kit. I certainly don't have any here with any of my (expansive) collection of rack-mount equipment.

H
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Re: Earth Bonding in a PDU

Postby wireman » Thu Jan 24, 2019 6:39 pm

ef37a wrote:A home made box would still have rack strips? (you COULD screw into hardwood rails but I would not recommend it) and as part of the "external metal surface" they would still need an earth bond not at the whim of a 13A plug?
.

Don't see why you have to protect yourself against 2 simultaneous faults. Would you bond a metal shelf to your house wiring in case some elecrical item you put on it went faulty and the case became live?
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Re: Earth Bonding in a PDU

Postby lazyrich » Thu Apr 25, 2019 8:04 pm

So I just bought a similar Olson unit from eBay, and doing a continuity check showed mains earth was not connected to earth on any of the outlets. The case and bonding point both were connected to the outlets. A Google led me here and confirmed my suspicion that this was a Bad Thing. So be careful with stuff you get from the internet.
Thankfully it was very neat inside, so wiring earth back in was straightforward, but not sure why it had ever been disconnected.
The mains lead had 3 cores and earth was connected at the plug end, but had been snipped off just inside the PDU, so pretty sure it had been 'modified' rather than being born like that.
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Re: Earth Bonding in a PDU

Postby ef37a » Thu Apr 25, 2019 8:31 pm

wireman wrote:
ef37a wrote:A home made box would still have rack strips? (you COULD screw into hardwood rails but I would not recommend it) and as part of the "external metal surface" they would still need an earth bond not at the whim of a 13A plug?
.

Don't see why you have to protect yourself against 2 simultaneous faults. Would you bond a metal shelf to your house wiring in case some elecrical item you put on it went faulty and the case became live?

Every rack unit I ever built or helped to build was earth bonded and even grids and doors that might not have made earth contact were made sure of with pig tails.

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