Electric Heater Install

[B7510HSD]

Ok so I'm going to install 2 120V electric heaters for my brother I read they require a 20 amp circuit....He has been told you can put up to 3 heaters on 1 20 amp breaker???? I say each should have it's oqn breaker?? Any hepl would be appreciated!!!!

 

[hr3]

Take the wattage of the heater "say 1200 watt" and devide by the voltage.. 120volt this gives you 10 amps.. A little too much for 2 heaters on one breaker..

 

[B7510HSD]

Take the wattage of the heater "say 1200 watt" and devide by the voltage.. 120volt this gives you 10 amps.. A little too much for 2 heaters on one breaker..

Thanks i'll ask him what the wattage is! :thumbsup:

 

[wyeguy]

And what if the voltage isn't always 120V? Do the math and see what happens to amps when volts drop for a given wattage. If the device says it needs a dedicated 20A breaker, all you're doing by NOT following their directions is giving the insurance company the opportunity to say," Nope, we're not paying for that fire." Or worse yet, getting someone hurt ain't worth saving a few bucks. Electricity is very unforgiving. Good luck!

I am the modern man...my smart phone smells of diesel & grease.

 

[Obed]

And what if the voltage isn't always 120V? Do the math and see what happens to amps when volts drop for a given wattage. If the device says it needs a dedicated 20A breaker, all you're doing by NOT following their directions is giving the insurance company the opportunity to say," Nope, we're not paying for that fire." Or worse yet, getting someone hurt ain't worth saving a few bucks. Electricity is very unforgiving. Good luck!

I am the modern man...my smart phone smells of diesel & grease.

I'm not certain the mfg said the heater required a dedicated circuit. I don't see that statement in the OP's post. But to be safe, I would use 110V in the calc instead of 120V. Amps drawn = x Watts/110V.
As long as the total amps drawn at one time do not exceed 20A on the 20A circuit, he should be fine. Make sure the 20A circuit uses no smaller than 12 guage copper wire and has a 20A breaker of course.

 

[B7510HSD]

Thanks guys I already have the wire strung so we are good there I always use 12/2 with ground I just couldn't figure out where his buddt old him he could put up to 3 heaters on the same circuit I always put them on seperate circuits like I will this time!!

 

[grsthegreat]

not to be a stick in the mud... but the NEC requires that heaters be considered continuous loads. Therefore a 20 amp breaker ACTUALLY can only supply 16 amps ( thats 80% of the 20 amp load).

 

[B7510HSD]

not to be a stick in the mud... but the NEC requires that heaters be considered continuous loads. Therefore a 20 amp breaker ACTUALLY can only supply 16 amps ( thats 80% of the 20 amp load).

Thanks I'll have to check what the wattage was..

 

[B7510HSD]

Ok he says the heater he bought is a 1000 watt so I would say a 20 amp circuit should be fine...

 

[grsthegreat]

i would say he can run 2 of those one a 20 amp circuit (dedicated) without any issues. Nothing else on that circuit.

 

[lovemytoys]

most heaters are 220 volt so one can do all three

 

[grsthegreat]

most heaters are 220 volt so one can do all three

he stated that these are 120v.... They sell both 240 and 120 models.

 

[B7510HSD]

i would say he can run 2 of those one a 20 amp circuit (dedicated) without any issues. Nothing else on that circuit.

That sounds good the specs I read online says it draws 8.3 amps I'll see wha he gets for the bedrooms....this one is in a bathroom and I am putting it on a GFI breaker..

 

[grsthegreat]

You dont HAVE to put a wall heater on a gfci breaker...even if its in the bathroom.

 

[Obed]

You dont HAVE to put a wall heater on a gfci breaker...even if its in the bathroom.

I installed a 240v heater in our bathroom without putting it on a gfci breaker. The electrical inspector didn't say anything about it. OTOH, he did verify that all my outlets were on gfci circuits. In fact I would be concerned that a heater might keep tripping a gfci breaker. The lighting in our bathrooms are not on gfci circuits either.
Obed

 

[B7510HSD]

The manual says it should be on a gfci breaker so he bought one so I guess I'll give it a try see how it works can't hurt! I have already switched the 2 outlets over to gfci type...

 

[chim]

And what if the voltage isn't always 120V? Do the math and see what happens to amps when volts drop for a given wattage........................

Did the math. The current and heat output both drop. The wattage is not a fixed value. It varies with the amount of voltage applied. The hot resistance of the heating element will not change appreciably with voltage variations . When less voltage is applied to a given resistance, the current drops as does the heater output. With 1000W and 120V the current is 8.33A Apply 100V in lieu of 120V and you'll get 7.64A and 840W.

 

[wyeguy]

I can agree to disagree. A resistive load, like a heater, will try to pull rated wattage till something burns up. An inductive load like a motor might be a different story, but resistance stays pretty constant. Good luck.

I am the modern man...my smart phone smells of diesel & grease.

 

[ThomasH]

That is incorrect. With lowered voltage, the current will drop, it's part of ohms law. I=V/R. And actually, a typical nichrome wire wound heater drops it's resistance when it is fully heated up, so the current draw is not linear. So while in theory it should draw 7.6x amps at 100 volts, I bet it's a tad less.

 

[Gittyup]

Installing 220V heaters will let you either run at lower current, or add more heaters to the circuit. For this reason, 120V heaters are far less attractive. Why would anyone use them, I don't know.