NEC or NOT

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kiss

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I just took an electrical exam with the following questions. What # is a UNDER VOLTAGE, OVER CURRENT, LOCK OUT RELAY, I have never heard of this. Has anyone else? Where can I find the answers?
The # they provided on the test were 21, 27, 51, 57, 86. They did mention some kind of standard, but I cant remember the wording. Any help is appreciated.
 
Re: NEC or NOT

The device (relay) designations are part of ANSI switchgear standards. They have nothing to do with the NEC.

The answers are 27(voltage), 57(current), and 86(lockout).
 
Re: NEC or NOT

Jim thanks for that reply, where can I find that on line? Any links you have are appreciated.
 
Re: NEC or NOT

Most switchgear and relay manufacturers have links for this information, I got this one from ABB. This site has a link to an attachment for relay numbers and ANSI codes.
 
Re: NEC or NOT

It is a sort of shorthand. You can put a great many devices on a single drawing, and only have to label each with a 2-digit number.
 
Re: NEC or NOT

Originally posted by jim dungar:
The device (relay) designations are part of ANSI switchgear standards. They have nothing to do with the NEC.

The answers are 27(voltage), 57(current), and 86(lockout).
Click to expand...
I believe "51" is the correct overcurrent device number.
 
Re: NEC or NOT

Bob,
You are correct 51 (which I believe actually means a time dealy overcurrent). This single number is then usually follwed by a letter like N, for neutral, or G, for ground. The most common application is as a 50/51 relay with breakers.
 
Re: NEC or NOT

To all the P.E.s out there, Do you think that this is a question/answer an electrician should know? I have almost 30 years in the business and never heard of this. I also asked about 10 other electricians with 20 years or more exp. and not one has heatd of this. P.S. I have commerc/residential experiance. Any input is appreciated.
 
Re: NEC or NOT

I can't speak for the other PEs. But if I issue a design that calls for a ?51 relay,? then you need to be able to buy the right one and to install it correctly. I don?t see that as an unfair question. But it might not apply to all areas within the electrical trades. A commercial application might see this type of design, but a residential will probably not.
 
Re: NEC or NOT

kiss
I agree with Charlie. Lots of electricians work on protective relaying, lots don't. If the tests are to be inclusive instead of exclusive, questions on most subjects should be asked. That being said, it is unlikely that very many electricians will answer every question correctly.
Jim T
 
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