15 & 20 AMP Circuit

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jvelaz1971
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Joined: Mon Feb 23, 2015 12:37 pm

15 & 20 AMP Circuit

Post by jvelaz1971 » Thu Feb 26, 2015 8:59 am

Hello Shannon,
Is there a simple way to determine how many watts a 15 & 20 AMP circuit can handle? Also, is there a simple way for me to determine how many watts are on a circuit?

Thank you

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Aaron
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Re: 15 & 20 AMP Circuit

Post by Aaron » Thu Feb 26, 2015 10:47 am

The formula is AMPS x VOLTS = WATTS.

15A x 120V = 1800 watts. That is the theoretical maximum load on a 15A circuit.
20A x 120V = 2400 watts. That is the theoretical maximum load on a 20A circuit.

But you also have to deduct for voltage drop of the wiring throughout your house, so it's really safest to deduct about 15% for that. So 1800 watts drops down to 1230, and 20A drops down to 2040.

There's a clamp meter that you can clamp onto each conductor running to a circuit breaker inside your breaker panel. The readout will give you the current running on the conductor with whatever load you have plugged in and running. They look like this:

Image

There's also this product called Kill A Watt that meters current from, say, an appliance you plug into it. My local public library actually loans these out.

http://www.p3international.com/products/p4400.html

jvelaz1971
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Joined: Mon Feb 23, 2015 12:37 pm

Re: 15 & 20 AMP Circuit

Post by jvelaz1971 » Thu Feb 26, 2015 11:07 am

This is very helpful information. Thank you so much!. The reason I was asking was, because I will be installing 5 - 7 recessed lights in my kitchen running of an existing wall switch and; I did not want to overload the circuit.

Thank you so much!

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Shannon
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Re: 15 & 20 AMP Circuit

Post by Shannon » Thu Feb 26, 2015 12:49 pm

Great explanation "akaase"!
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emtnut
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Re: 15 & 20 AMP Circuit

Post by emtnut » Mon Mar 02, 2015 7:26 am

Hi Jvelaz ,

I would recommend you check with your local authority/codes for this project.

POT lights (recessed lights) have many code requirements due to the heat generated by these units.
For code in my location, they have not updated anything yet even if you are using LED lighting.... since someone could still install an incandescent.

Cheers

Wayne
~~ Ford Ford Ford Ford Ford Ford :mrgreen: ~~

jvelaz1971
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Re: 15 & 20 AMP Circuit

Post by jvelaz1971 » Mon Mar 02, 2015 7:58 am

ok I will confirm with my local codes.
Thanks

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emtnut
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Re: 15 & 20 AMP Circuit

Post by emtnut » Mon Mar 02, 2015 6:29 pm

If you are using IC rated recessed luminaires, you have to rate your cable according the the luminaires temp rating (which can reduce your total wattage available on that circuit). There are also connection box accessibility requirements that are area specific, however some of these units come with an integral connection box.

Non IC rated cannot be installed near any insulation, and many other restrictions.

Personally, I would install IC type even if I was clear of any insulation !

Hope that helps out ... I know here in Ontario, Inspectors are very stringent on POT lights due to fire hazards.

Wayne
~~ Ford Ford Ford Ford Ford Ford :mrgreen: ~~

jvelaz1971
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Re: 15 & 20 AMP Circuit

Post by jvelaz1971 » Mon Mar 02, 2015 7:44 pm

I certainly will install IC
Thanks

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