Give 100%

[GG]

How many agree with this quote from Electrical Wiring Residential by Ray C. Mullin, 2005, pg.559. "The NEC permits 100% loading on an overcurrent device ONLY if that overcurrent device is listed for 100% loading. See NEC 210.20 & 215.3. At the time of this writing, UL has NO listing of residential-type molded case CB's that are suitable for 100% loading. A max. loading of 80% is good practice - less is even better!".

 

[LarryFine]

Re: Give 100%

Okay, I'll bite.

I agree, with the caveat that the statement: "At the time of this writing, UL has NO listing of residential-type molded case CB's that are suitable for 100% loading." is true.

Now, having said that, there's no real opinion given here, only fact. What's to disagree with?

 

[iwire]

Re: Give 100%

Originally posted by GG:
How many agree with this quote from Electrical Wiring Residential by Ray C. Mullin, 2005, pg.559. "The NEC permits 100% loading on an overcurrent device ONLY if that overcurrent device is listed for 100% loading.

I do not agree.

The NEC and UL allows 100% loading of any overcurrent device up to 2 hours, 59 minutes and 59 seconds.

 

[GG]

Re: Give 100%

I can remeber a long thread a while back where everyone was saying that you can load a breaker to 100%, and Mr. Mullin is saying its not allowed.

 

[iwire]

Re: Give 100%

From the 2004 UL White Book

CIRCUIT BREAKERS, MOLDED-CASE AND
CIRCUIT BREAKER ENCLOSURES (DIVQ)

Part of the section called use

Unless otherwise marked, circuit breakers should not be loaded to exceed 80 percent of their current rating, where in normal operation the load will continue for three hours or more.

 

[jimwalker]

Re: Give 100%

and on that final second that makes 3 hours it magically trips.But all that needs to be done is reset and we are good for another 2 hours 59 minutes and 59 seconds.Do breakers have a clock built in ?

 

[iwire]

Re: Give 100%

Originally posted by jimwalker:
Do breakers have a clock built in ?

Notice I have never on this forum suggested 100% loading was a good plan.