Max. Ckt. Breaker Load

[wilsonv]

We are going to install a new sports lights system on an existing ballfield. The existing A/C Panel is a 480, 3ph, 225A. The new load is 160A and after appling the continuous operation factor is 200A (160*1.25).
1. Can I use the existing A/C Panel?
2. It is right that the breakers can be loaded up to a maximum of 80% of his rating? If this is correct, I need help to find were is this rule described.
Thanks.

 

[rbulsara]

Refer to articles in NEC describing the following:

1. Panelboards and switchboards
2. Branch Circuits, Feeders and Service etc.

In them you will find this. It IS there, I suggest you find it rather than I. (Grin)

Hint: you can use 100% rating if the assembly is listed for such use.

 

[wilsonv]

I have not fouded yet rbulsara. That's why I'm asking for some help. Thank you for your response I will keep looking in the NEC this weekend. Thanks again.

 

[wareagle]

You will not find that in the NEC. It is found in the MFG spec for breakers. The 125% rule for continuous load is found in various locations in the NEC. IF there is only 160 amps continuous on the panel then you should be able to use it. Take care to balance the load.

 

[alehman]

Look in article 215, "Feeders".

 

[rbulsara]

Wareagle:

May be you should look up the Code too...

 

[wareagle]

rbulsara
Perhaps you would be kind and point out the section that says "breakers can be loaded only up to 80% of its rating for continuous loads". It am not asking for the 125% rule. I know where that is in the NEC.
WilsonV's post was "2. It is right that the breakers can be loaded up to a maximum of 80% of his rating? If this is correct, I need help to find were is this rule described."
Please show us where it is in the NEC.

 

[rbulsara]

OK ..when i get back in office next week..

 

[mc5w]

Look in articles 210 and 240.

What other load is on this existing panel?

Mike Cole

 

[bigbillnky]

Goodmorning wilsonv
I will try and see if I can help provide some information that may be of some help. You did not mention if this panelboard is service equipment, or if it is a feeder providing power for the lighting load. Sometimes that will help lead to the correct article to reference and make a difference in the correct application of an article. This is actually a more difficult question than it used to be. Article 384-16(d)(switchboards and panelboards) of the 1999 NEC stated that the total load on ANY overcurrent device located in the panel could not exceed 80% of the devices rating. Since the code stated "any", this article applied to the rating of the main overcurrent device also. In the 2002 NEC, Article 408 covers switchboards and panel boards. The article covering the 80% rule was purposely omitted from this article. The reason was the fact that when you calculate either feeder or branch circuit overcurrent protection(Articles 210.20(A) and 215.3), you must calculate the continous load at 125%. If the actual load calculation is correct, then there will be no need to further derate the panels ampacity. All that is required of the panelboard is that it has a minimum ampacity rating based on the total connected load as calculated by Article 220. Hope this has helped.

Bigbillnky,C.E.F.....(Chief Electrical Flunky)

 

[wilsonv]

Thanks to all you.
bigbillnky, this a Panelboard providing power to the lights. My interpretation of Article 210.20A is that I can load a breaker 100% with only noncontinuous load even when the device is not listed to operate 100%. Is this interpretation right? If is right I have found the answer to my question. Thanks a lot.
rbulsara: Thanks, I understand there is people out there that are trying to get it easy. All I was asking is where the 80% rule appears.
Wareagle: Thanks for your help and do not worry the load will be balanced.
mc5w: Thank you, the only loads in this panel will be lighting.

 

[bigbillnky]

You are absolutely correct with your interpretation of article 210.20A. Sometimes the NEC is not as user friendly as it should be, especially when they change the articles around each code cycle. I'm glad I was able to help!

Bigbillnky,C.E.F.....(Chief Electrical Flunky)

 

[alehman]

Article 215 has the same wording as 210.20.

Also, 384.16: "The total load on any overcurrent device located in a panelboard shall not exceed 80% of its rating where, in normal operation, the load will continue for three hours or more"
Exception: An assembly, including the overcurrent device, shall be permitted to be used for continuous operation at 100% of it rating where it is listed for this purpose.

Lighting is usually considered to be continous load.

 

[wareagle]

2003 UL White Book
CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVQ)PRODUCT TYPE
MAXIMUM LOAD
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 3 hours or more.

 

[wareagle]

alehman
What version of the code are you using? NEC 2002 does not have any instructions regarding the use of a breaker at 80%
of its rating that I see.

 

[rbulsara]

use the crossreference listed for NEC 2002 and 1999. The article no. is changed..

 

[wareagle]

rbulsara
WilsonV's origional post was "It is right that the breakers can be loaded up to a maximum of 80% of his rating? If this is correct, I need help to find were is this rule described."
I said that that the 80% rule was not found in the NEC.

You reply was "Wareagle:
May be you should look up the Code too..."

Article 215 references the use of the 125% factor. It does not say apply 80% to the breaker rating.
My point is the if Wilson searched the current version 2002
NEC, which I use, he will not find a reference the the 80% factor. As I pointed out the 80 % is found in the 2003 UL White Book
CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVQ).

 

[rbulsara]

wareagle:

See alehman's post....and mine following it...

 

[rbulsara]

wareagle:

OK. Here my research during my lunch..(hate to do that..)

I do owe an apology because of NEC's rearrangement, but it still does not change the requirement of not loading more than 80% unless, the OCPD or assembly is 'listed' for use at 100% of its rating.

2002 NEC article 408 which replaced 1999 article 384 removed the particular paragraph that used to be 384.16.(d) "coninuous load" , which alehman indicated and I was alluding to.

However, it was a redundant statement to what article 215.2(A), 215.3, 210.19.A and 210.10A in NEC 2002 requires.

215.3 in 2002, do require OCPD also to be sized for 125% of the continuous load. Which is same as not loading it more than 80% unless listed for use at 100%.

Also continuos load is defined as the load expected to continue more than 3 hours or more.

 

[wilsonv]

rbulsara:

Let's say that you have a 100A Breaker, and it's not listed for use at 100%. You have calculated a non continuous load of 90A, Can you use the 100A Breaker or do you need to use a 125A Breaker?. My answer will be that I can use the 100A Breaker, based on Article 215.3