Does The 80% Of Peak Rule Apply To Extension Cords? - Electrical - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum Does the 80% of peak rule apply to extension cords?
 Register Blogs Articles Rewards Search Today's Posts Mark Forums Read

02-20-2010, 09:05 PM   #1
Member

Join Date: Feb 2010
Posts: 35
Rewards Points: 25

## 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?

02-20-2010, 09:19 PM   #2
Member

Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000

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

 02-20-2010, 09:25 PM #3 Member     Join Date: Mar 2005 Location: Welland, Ontario Posts: 13,474 Rewards Points: 13,748 Blog Entries: 11 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."

02-20-2010, 09:29 PM   #4
Member

Join Date: Feb 2010
Posts: 35
Rewards Points: 25

Quote:
 Originally Posted by joed 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?

 02-20-2010, 09:29 PM #5 Member   Join Date: Feb 2010 Location: Oklahoma Posts: 992 Rewards Points: 506 Is the 80% rule intended to address the circuit's overload protection or its conductors? This might answer your question.
 02-20-2010, 09:36 PM #6 Member   Join Date: Feb 2010 Posts: 35 Rewards Points: 25 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)
 02-20-2010, 09:40 PM #7 Wire Chewer     Join Date: Jun 2009 Location: Ontario, Canada Posts: 3,355 Rewards Points: 138 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.
 02-20-2010, 09:45 PM #8 Member   Join Date: Feb 2010 Location: Oklahoma Posts: 992 Rewards Points: 506 Wouldn't you already be limited to 80% of the hard circuit to which your cord is plugged in?
02-20-2010, 09:54 PM   #9
Member

Join Date: Feb 2010
Posts: 35
Rewards Points: 25

Quote:
 Originally Posted by jlmran 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

02-20-2010, 09:56 PM   #10
Member

Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000

Quote:
 Originally Posted by jlmran 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

Quote:
 Originally Posted by Delta223 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" ?

02-20-2010, 10:43 PM   #11
Member

Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Rewards Points: 500

Quote:
 Originally Posted by joed 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!!!

02-20-2010, 10:51 PM   #12
Member

Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Rewards Points: 2,000

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

02-20-2010, 11:04 PM   #13
Member

Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Rewards Points: 500

Quote:
 Originally Posted by Scuba_Dave 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.)

 02-20-2010, 11:09 PM #14 Member   Join Date: Jan 2009 Location: South of Boston, MA Posts: 17,248 Rewards Points: 2,000 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
02-20-2010, 11:36 PM   #15
Member

Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Rewards Points: 500

Quote:
 Originally Posted by Scuba_Dave 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!!!

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post alnoir Electrical 17 10-21-2009 05:37 PM jamiedolan Electrical 10 02-27-2009 09:26 AM Ultrarunner2017 Electrical 23 01-20-2009 09:11 PM

Top of Page | View New Posts