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Allowed load on a circuit

e hilton

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Jul 2, 2014
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I’m watching a discussion on another general construction forum about how much load can be put on a circuit. Let’s say it’s a 15A residential circuit for receptacles. One person says max load is 80% or 12A. Another says that a myth, it can be loaded to 100% for up to 3 hrs. What does code say?
 

Mark K

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Can either provide a code reference for their position. Until they can provide a code reference my assumption is that they are making it up.
 

jar546

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That is a loaded question unless you are being very specific. The answer will vary based on whether or now there are known loads for specific receptacles such as an appliance or equipment. In residential, you can put 100 receptacles on a single circuit if you want, providing they are general use receptacles.
 

jj1289

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The capacity of the circuit will also be affected if it has motor loads connected to it. As stated earlier, need to provide more specific information
 

north star

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# > # < #

e Hilton,

Do you know what the applicable Code in your OP is ?

In the `17 NEC, refer to Article 220.18 for [ Branch Circuit ]

Maximum Loads.

# < # > #
 
Last edited:

e hilton

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Sorry north, I don’t have a copy of the nec. I’m not on the BI side, I’m a commercial project manager.
 

ICE

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California concrete jungle
210.23(A)(1) Cord-and-Plug-Connected Equipment Not Fastened in Place.
The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating.
 

e hilton

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I have been doing a little research on the web, and I’m not finding a clear answer. However i did find something that says the breaker (ocpd) is to be sized at 125% of the calculated continuous loads. Working backwards, that limits the load to 80% of the breaker size. Right?
 

north star

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$ $ = $ $

e hilton,

To be able to determine the limitations on a circuit, what the circuit is intended
for will need to be known \ provided.

80% of what type of circuit ?.....General use receptacles, ...small appliances, ...lighting,
countertop receptacles, etc., etc.


$ $ = $ $
 

Paul Sweet

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Oct 17, 2009
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Richmond, VA
NEC defines Continuous Load as a load where the maximum current is expected to continue for 3 hours or more. NEC 210.19(A)(1)(a) limits branch circuit loads to the sum of the noncontinuous load plus 125% of the continuous load.

Few loads are considered noncontinuous, especially receptacle loads, where people think nothing of plugging supplementary electric heaters into adjacent rooms that might be on the same circuit.
 
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