ECN Forum Forums Code Related Discussion NEC & other Code issues Voltages used for branch circuit calculations

Don, I absolutely agree that if the question used a higher or lower voltage the calculation would have to use that voltage.

I don't see the issue with the question.

The NEC® has decided the wording "Unless other voltages are specified " has a reason to be in the article. With that said, who is going to be available to champion the exam taker when he / she uses the argument that the question is bogus per the experts on these forums?

If we changed the wording of the question to say "using all the applicable articles but substitute 115v for 120v ; would it change the math? Would it change the fact that there is a limit to receptacles per circuit in a commercial facillity and not in a dwelling? These are the real reasons the question would be given.

Roger

[This message has been edited by Roger (edited 08-03-2003).]

So guys, where do we go from here? In my area we have voltages that range from 115 to 125v, every place is different. So what answer are we going to settle on, 10 ,12 or 13? My answer is still 10, due to the fact that we cannot load the circuit above 80%.

Zapped208, please explain or tell where the 80% or 125% numbers are applicable or addressed in a receptacle circuit? How could we know an unknown load would be continuous? The only reason we would apply the 180va to a receptacle is it would be an unknown load.

Roger

Why can't we do the calculation like this:
180va/115v = 1.565 amps. 1.565 amps times 13 receptcles = 20.348 amps. 220.2(B) permits fractional amps less than 0.5 to be dropped.

I always thought the answer was 13

Bill

Don, if the question asked for the total amps of 13 receptacles on a 115v circuit you would be correct.

As bad as we may dislike the question, the answer as it is worded is 12. (sorry Bill)

Roger

Roger,
There is nothing question that tells me how I have to make the calculation. It is simply a load calculation question. Both methods of working the problem are equally correct. One method gives an answer of 12 the other method gives an answer of 13.
Don

Roger,

I was basing my answer of 13 using a nominal voltage of 120v and not applying any 80% or 125% adjustment. Sorry, I was not addressing the original question.


Bill

OK Joe your turn.

If the worms crawl into the ground now that the can was opened, just grab a Megger