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Power cable [message #22704]

Thu, 26 March 2015 06:58

stevem
Messages: 4730
Registered: June 2004
Location: NY

Senior Member

To all of you / us who have or will change over equipment old gear from a ungrounded set up to a 3 prong unremovable cable take note that UL requires that the ground wire of the cable be long enough in relation to the other two wires that should the cable get ripped out of the gear that the ground wire will stay hooked up and still remove the shock issue and blow the breaker the gear is powered from!

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Re: Power cable [message #22705 is a reply to message #22704]

Thu, 26 March 2015 09:16

C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...

Senior Member

I think if you wire the cord in the fashion as the original black and white conductor, the ground wire will be longer. But really, what lawyer came up with that one?
Conrad

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Re: Power cable [message #22706 is a reply to message #22705]

Thu, 26 March 2015 11:37

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

If I'm not mistaken, the UL rating applies to the manufacturer of a product as to its safety. Once you make a change of any kind from the original design, the manufacturer is no longer legally obligated to any charges in the event the product causes damage or harm. So by changing the cord, you have now changed the original design of the amp and the UL rating is of no consequence. You now have a safer amp, but you can't go back on anyone if it catches fire and burns your house down. Only the manufacturer can make the changes or their agent for the UL rating to be still viable.

I think the point Stevem is trying to make is that if the ground wire stays intact, there is less chance of shorting out any of the components. In the food service equipment that I work with, rarely does having the ground wire still connected keep from blowing anything else. If anything, it keeps people from getting zapped in the even of a short and you becoming the ground.

[Updated on: Thu, 26 March 2015 11:45]

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Re: Power cable [message #22707 is a reply to message #22706]

Thu, 26 March 2015 12:31

C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...

Senior Member

First off, I have been in the electrical trade for 40+ years. My lawyer quip was just to be snarky. I am more than educated on the reasons for grounding in any piece of electrical equipment. I guess I found it rather funny that UL would make a requirement of unremovable cordage having the ground wire being longer to assure that it remains connected after/during its forcible removal. The assumption is that the circuit should and would be cleared during that infraction before the ground wire is ripped from it's comfortable terminal. Lawyers and bean counters just make things interesting for the guys who actually do the work.
Conrad

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Re: Power cable [message #22708 is a reply to message #22704]

Thu, 26 March 2015 15:45

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

As I understand it, the hot and neutral can be connected with push on terminals, like on the back of the power switch, while the ground wire must be bolted to the chassis at its own isolated connection point. The ground point must be marked with a ground symbol.

The ground wire must be made of such length that if the cord is pulled out and the hot and neutral wires become disconnected, the green ground connection will remain connected to the chassis or at least be the last wire to come loose.

In most of the vintage Kustom amps the power cord travels a long way to get to the power switch and fuse block. The wire would probably fail at the strain relief before any wire got pulled from the solder points.

All of this information really doesn't mean much to the average do-it-your-selfer. I doubt that most will understand or care about getting it right. As long as the amp works and there are no more mic shocks they're happy. It really only applies to those of us that do this stuff professionally and need to care about liability.

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Re: Power cable [message #22709 is a reply to message #22708]

Thu, 26 March 2015 15:56

C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...

Senior Member

Point well taken!
Conrad

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Re: Power cable [message #22710 is a reply to message #22704]

Thu, 26 March 2015 18:46

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

Agreed!

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Re: Power cable [message #22711 is a reply to message #22704]

Fri, 27 March 2015 06:12

stevem
Messages: 4730
Registered: June 2004
Location: NY

Senior Member

My point was also towards those of us who have done this for friends in our band or local jam crowd folks as if something bad takes place the law suite mentality that prevails today can make life suck real fast!

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Re: Power cable [message #22712 is a reply to message #22704]

Fri, 27 March 2015 11:01

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

Yeah, unfortunately that is very true.........friendship goes right out the door when BIG money gets mentioned. Since I own my own business, I will not work on a piece of equipment that has been modified or the customer "wants" me to do what ever it takes to make it work. Its not worth the liability and I don't want to find out the hard way just how good my insurance company is or isn't.

Sorry Conrad..........sorry I missed your joke, thought you were being serious since I don't know you. Too many late nights Smile

[Updated on: Fri, 27 March 2015 11:05]

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