# Understanding continuous & non countinous loads

Originally Posted By: Kevin Blackwell
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Could one of the NEC consultant please explain too me the time frame of how long and what percentage of voltage is applied that determine if it’s continuous or non continuous load?

(example is this true) voltage applied for 3 hour or more at 100% is an continuous load?

Thanks from the confused!!!!!!!!!!!!!!!!!!!!!!!!!!!

Originally Posted By: Ryan Jackson
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You got it.

Continuous load is defined in article 100: A load where the maximum current is expected to continue for 3 hours or more.

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Ryan Jackson, Salt Lake City

Originally Posted By: Bob Badger
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To be accurate use the word current in place of voltage.

Think of a faucet turned off, the pressure (voltage) is there, the flow (current) has stopped.

From the NEC definitions.
 Quote: Continuous Load. A load where the maximum current is expected to continue for 3 hours or more.

Ryan and I may see things differently (isn't the NEC great ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif) ) In my opinion there are very few circuits in a dwelling units that must be treated as continuous loads.

You can say someone may leave a few lights on all day but it is unlikely all the loads on that circuit would be on together for 3 hours or more.

This wording "maximum current" IMO makes it clear, that one or two things on a circuit on all day does not make the whole circuit subject to the continuous load rules.

There are some loads that we always have to treat as continuous, an electric water heater under 120 gallons is one.

A circuit that is considered a continuous load must be wired for 125% of the full load current.

What this means for continuous load dwelling unit circuits is this.

30 amp breaker no more than 24 amps of continuous load
20 amp breaker no more than 16 amps of continuous load
15 amp breaker no more than 12 amps of continuous load

Remember this is for continuous loads, non-continuous loads can load the breaker to 100% of its rating.

Sorry to ramble on so long

Bob

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

Originally Posted By: roconnor
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 Bob Badger wrote: Think of a faucet turned off, the pressure (voltage) is there, the flow (current) has stopped.

I always liked that analogy ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: Kevin Blackwell
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Ryan & Bob,

Thanks a million for the conformation.

From: Kevin the (not so confused)