# Newbie electrical circuit load Q

• posted on November 5, 2012, 7:24 pm
Hi all
I have a Cadet style heater that is 1000 watts. It lives on a dedicated 15 amp 220V circuit.
I want to install a second heater that is 750 watts. Ideally it would share the same circuit, as physically it would located about 10' from the first heater, and at the opposite end of the house from the panel.
I can't recall the calculations for load on a circuit. Would 1750 watts possible peak be too much for this circuit?
Tnx for tips Gary

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• posted on November 5, 2012, 8:05 pm
Provided that the wire gauges are all up to code, you should be ok.

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• posted on November 5, 2012, 9:50 pm
On Mon, 5 Nov 2012 12:05:18 -0800 (PST), snipped-for-privacy@gmail.com wrote:

Extremely unlikely to be wired for less than 15 amps. I'm suspecting Europe or GB with 220 volts used for something as anemic as a 1000 watt heater. Virtually NEVER see 15 amp 220 (or 240) volt circuits in North American residential wiring.

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• posted on November 5, 2012, 8:13 pm

The wattage is simply the volts times the current in simple resistive loads. That would be 220 times 15 for 3300 watts total. As you only have a load of 1750 you should be fine.
Working backwards, 1700 watts deviced by 220 volts is about 8 amps, so again you should be fine. You have almost twice the capacity you need in the circuit. Also most voltages are 240 now, but that would not make much differance in your case as you have plenty of capacity to spare.

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<%-name%>
• posted on November 5, 2012, 9:23 pm
On Monday, November 5, 2012 12:13:20 PM UTC-8, Ralph Mowery wrote:

Thanks. I believe it is wired with 12ga, will have to check. When I did the original wiring I did this same research, you'd think it might have stuck..
Then again, I had not anticipated putting a second heater on the circuit at that time.
Can I assume 12ga would be ample for this need?

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<%-name%>
• posted on November 5, 2012, 9:53 pm
wrote:

Unless you are running 100 feet of the stuff, 14 ga copper is adequate. 12 ga if it is aluminum

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<%-name%>
• posted on November 6, 2012, 2:48 am
My bad, It is a 240V circuit, don't know what possessed me to write 220.
The length of the physical wire is less than 50 feet, so I will confirm it is 12ga and branch off the existing circuit to power the second heater.
Thanks much to all for the tips and advice.

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<%-name%>
• posted on November 6, 2012, 4:11 am
wrote:

As was posted earlier, 14ga is OK on a 14a breaker.
As long as you stay under 2800 watts you will be OK

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<%-name%>
• posted on November 12, 2012, 7:56 pm
So for the final update... I checked the wiring, and for some reason I used 14ga. arg.
Circuit is 240 15amp.
The run from the breaker box to Heater #1 (1000 watts) is about 25 feet. The run from Heater #1 to Heater #2 (750 watts) is about 15 feet. I would pony off this circuit and use 14 ga wire again.
So that is a total of 1750 watts on the circuit, using 14ga wire.
I just want to ensure there are no safety risks in adding this second heater to the circuit, now knowing that the wire is a smaller gauge than I originally thought.
Thanks all

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<%-name%>
• posted on November 12, 2012, 9:12 pm
wrote:

the circuit, now knowing that the wire is a smaller gauge than I originally thought.

#14 is good for 15 amp circuit - derate 20% for full constant load - you are good for 12 amps - and you only have about 7.3 amps load on the circuit. You are good to go.

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<%-name%>
• posted on November 5, 2012, 9:44 pm
wrote:

the same circuit, as physically it would located about 10' from the first heater, and at the opposite end of the house from the panel.

1750 watts on 220 is just under 10 amps. You are allowed 80% of breaker rating for full load - so .8X15 amps. You are good to go.
The formula is watts=V*A for a resistive load.

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<%-name%>
• posted on November 5, 2012, 10:11 pm
On Mon, 05 Nov 2012 16:44:38 -0500, snipped-for-privacy@snyder.on.ca wrote:

the same circuit, as physically it would located about 10' from the first heater, and at the opposite end of the house from the panel.

If this is a US heater, it was rated at 1000w @ 240v. It will be less than that at 220v. (the resistance of the element will be the same) In real lift I bet he has something close to 240. Around here it is closer to 248-249 so that 1000w heater will actually be putting out more. (~1064-1091w or so)

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<%-name%>
• posted on November 5, 2012, 9:58 pm
Amps x volts = watts.
Now you can calculate the watts that the circuit will bear.
Hi all
I have a Cadet style heater that is 1000 watts. It lives on a dedicated 15 amp 220V circuit.
I want to install a second heater that is 750 watts. Ideally it would share the same circuit, as physically it would located about 10' from the first heater, and at the opposite end of the house from the panel.
I can't recall the calculations for load on a circuit. Would 1750 watts possible peak be too much for this circuit?
Tnx for tips Gary

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<%-name%>
• posted on November 5, 2012, 10:40 pm
On 11/5/2012 4:58 PM, Stormin Mormon wrote:

How many amps in a volt?

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<%-name%>
• posted on November 7, 2012, 7:10 pm
On 11/05/2012 04:40 PM, Anita Dick wrote:

It's the same as the number of peaches in a potato :-).
--
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