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Old 02-20-2010, 09:05 PM   #1
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Does the 80% of peak rule apply to extension cords?


I know you're not supposed to have a continuous load on a circuit for more than 80% of its peak capacity. Does this apply to extension cords too?

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Old 02-20-2010, 09:19 PM   #2
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Does the 80% of peak rule apply to extension cords?


It's a good idea
For me it would depend upon the circuit, the wiring & the device being used
I ran an 18.6a (Max) pool pump on a 20a circuit for an entire summer &into the next summer
That's 93% of the circuit
I never tested it with a meter..may have actually pulled less then that
But it did trip the circuit on one hot day

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Old 02-20-2010, 09:25 PM   #3
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Does the 80% of peak rule apply to extension cords?


80% rule only applies to continuous loads.
A continuous load is defined as "a load where the maximum current is expected to continue for 3 hours or more."
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Old 02-20-2010, 09:29 PM   #4
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Does the 80% of peak rule apply to extension cords?


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80% rule only applies to continuous loads.
A continuous load is defined as "a load where the maximum current is expected to continue for 3 hours or more."
Right, so a 20A circuit should not have a continuous load of more than 16A.

Now for my question, can a 20A cord have a continuous load of more than 16A, or does the same issue apply to extension cords?
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Old 02-20-2010, 09:29 PM   #5
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Does the 80% of peak rule apply to extension cords?


Is the 80% rule intended to address the circuit's overload protection or its conductors? This might answer your question.
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Old 02-20-2010, 09:36 PM   #6
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Does the 80% of peak rule apply to extension cords?


To be honest I'm not sure. I know going over 100% trips the breaker, but staying in that 80-100% threshold for too long slowly fries the circuit. So I would assume the cord itself would be fine to a full 20A (not a hair more though)
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Old 02-20-2010, 09:40 PM   #7
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Does the 80% of peak rule apply to extension cords?


I don't know about code, but I would just go with the assumption of yes, especially because some cords may actually not even be 14awg. If you do plan to have a continuous load on an extension cord get a heavy duty 12awg one to play it safe.
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Old 02-20-2010, 09:45 PM   #8
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Does the 80% of peak rule apply to extension cords?


Wouldn't you already be limited to 80% of the hard circuit to which your cord is plugged in?
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Old 02-20-2010, 09:54 PM   #9
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Does the 80% of peak rule apply to extension cords?


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Wouldn't you already be limited to 80% of the hard circuit to which your cord is plugged in?
No because my cord is actually rated for 15A
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Old 02-20-2010, 09:56 PM   #10
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Does the 80% of peak rule apply to extension cords?


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Originally Posted by jlmran View Post
Wouldn't you already be limited to 80% of the hard circuit to which your cord is plugged in?
There isn't any 80% load rule in residential for plug in items
How many people go around & test everything they have plugged into a circuit?
They don't...instead if the breaker trips they then move something to a different circuit
I wouldn't doubt in some places I have lived that I have run loads very close to the circuit rating for a long time
Especially in Apts

210.23 An individual branch circuit shall be permitted to supply any load for which it is rated

It does then go on in a sub section & indicates that no (1) item plugged in should pull more then 80% of the circuit


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Originally Posted by Delta223 View Post
I know going over 100% trips the breaker, but staying in that 80-100% threshold for too long slowly fries the circuit
What are you basing this on ??
Specifically the "slowly fries the circuit" ?
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Old 02-20-2010, 10:43 PM   #11
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Does the 80% of peak rule apply to extension cords?


Quote:
Originally Posted by joed View Post
80% rule only applies to continuous loads.
A continuous load is defined as "a load where the maximum current is expected to continue for 3 hours or more."
And a pool circulator pump Does run for more than Three Hours!!!
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Old 02-20-2010, 10:51 PM   #12
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Does the 80% of peak rule apply to extension cords?


Not mine !! On 2 hours.....off for 15 min...on 2 hours
That was connected Temp while I ran a 60a sub
Its now converted to 240v & hard wired

Another thought:

Quote:
Conductor sizing. You must size conductors no less than 125% of the continuous loads, plus 100% of the noncontinuous loads [210.19]. Base this on the terminal temperature rating ampacities as listed in Table 310.16
Soooo....12g is rated 25a ampacity * 80% continous load = 20a continous
14g rated 20a ampacity * 80% = 16a....hmmmmm
But breaker kicks before that
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Old 02-20-2010, 11:04 PM   #13
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Does the 80% of peak rule apply to extension cords?


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Originally Posted by Scuba_Dave View Post
Not mine !! On 2 hours.....off for 15 min...on 2 hours
That was connected Temp while I ran a 60a sub
Its now converted to 240v & hard wired

Another thought:



Soooo....12g is rated 25a ampacity * 80% continous load = 20a continous
14g rated 20a ampacity * 80% = 16a....hmmmmm
But breaker kicks before that
The one at my relative's house Does! In any case, 80% of capacity and 125% of demand are both sides of the (same) equation. (I know, it's a no brainer, but I had to let that thought out. Because it was news to me the first time I checked it out.)
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Old 02-20-2010, 11:09 PM   #14
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Does the 80% of peak rule apply to extension cords?


Right...but people are basing it off the OCPD instead of the ampacity

I was going to change that time to 2 hours 59 minutes....
But you already quoted me

Actually once I animate my Christmas display I shouldn't have to worry too much about my lights being on continous..blink....blink
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Old 02-20-2010, 11:36 PM   #15
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Does the 80% of peak rule apply to extension cords?


Quote:
Originally Posted by Scuba_Dave View Post
Right...but people are basing it off the OCPD instead of the ampacity

I was going to change that time to 2 hours 59 minutes....
But you already quoted me

Actually once I animate my Christmas display I shouldn't have to worry too much about my lights being on continous..blink....blink
You should open a Law practice. the (ingenious) way that you find loopholes.! Better yet. A Legal Loophole advice firm. Where lawyers can contact for instant (packaged) loopholes!!!

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