Run 4800W construction heater off 15A?

[Howard Sterndrive]

I have two 14 ga 15 amp circuits in my detached garage.

The 2 circuits come from opposite sides of my panel, so there is 240V out there.

I wired up an outlet for my Lincoln MigPak 180 welder from hot to hot off each supply. It works fine. It requires 20A peak according to its specs, but has never popped a 15A breaker.

I would like to plug a 4800W construction heater into it...was going to lop off the heater's plug and just put the same type as on the welder..... it should pull 20A at 240V.... think it'll pop the 15A breaker?

before I waste $80 on the heater.... I suppose it could be turned down too...I haven't looked closely at those heaters....

A 3500 watt heater would be nice, but they all seem to be 4800W

 

[Fireman431]

Re: Run 4800W construction heater off 15A?

If it requires a 20A breaker, even at start up, there's a good chance it will pop the 15A.

As an idea, I needed a 20A breaker for a 115v welder I have. I punched in a 20A breaker in a blank slot in the panel box and mounted the receptacle right under the panel. No need to fish wires everywhere. Use a cut-in box, drop 12" of 10/2 (with a ground) through the bottom of the panel. Complete in about 30 minutes!

 

[Bigprairie1]

Re: Run 4800W construction heater off 15A?

Howard is the basically electrical equation that might prove helpful:
P=VI or in descriptive terms:
Power (watts) = Volts x Current (amps)
so in your case:
4800 watts = (120V) x ____ amps ........or in calculated resolution:
4800watts/120volts = 40 amp circuit required (with 120 volts)
So
You can try it but I don't think there is anyway that a 15 amp breaker is going to be able to ever safely hold a 4800 watt load....seriously.
(noting that in actual fact a 15 amp circuit might be able to run a 1800-2000 watts somewhat safely...although spec never goes over 1500 watts for these circuits).
Still....if you do it.....let us know what happened, could be an interesting result...just make sure you are using an excellent breaker.
Good Luck ( you might need it)
BP

 

[Howard Sterndrive]

Re: Run 4800W construction heater off 15A?

it's a 240V heater, BP

so 4800/240 = 20A

If I could figure a way to get the neutral to carry current, I'd be laughing.

I'm thinking maybe two 1500W 120V microfurnaces would be the way to go instead...

 

[Bigprairie1]

Re: Run 4800W construction heater off 15A?

....you are getting closer to something workable Howard, if you can take advantage of a 240V supply.
Now the next thing to consider is your wire. 14Ga. won't cut it (safely) for a 20amp load....what about getting at least 12 Ga. in there or larger ideally?
The biggest point here I am trying to make is that if something goes south and there is a fire....the insurance company won't hesitate about walking away with absolutely zero liability towards you....not even close. They love these 'home wiring' scenarios with respect to payouts simply because....there are none.
Take care and make sure what you are doing is going to work safely and make sure that any possible short cuts are worth the risk....and know what they are.
Good Luck
BP

 

[joed]

Re: Run 4800W construction heater off 15A?

Buy two 1500 watt 120volt heaters and plug one into each circuit.

This sounds like a possible entry for the SHT forum.

 

[jlinder]

Re: Run 4800W construction heater off 15A?

When wiring a heater you need to go even further. A heater draws a constant high current for extended periods of time. According to code, when you have a device that does this you <B>must</B> derate the wire capacity to 80% of normal. For example, a 12 GA wire that normally is rated for 20A is only allowed to carry 16A.

In your case you would need to put in 10ga wire and a 30A breaker. Code says this could support 24A (30A x 80%) heater draw, or a max of 5760w at 240v.

If you have 14ga wire that is normally rated for 15A, but in this case code says you can only have a heater that draws 12A, or 2880w at 240V

Yes, the circuit breaker may not blow, (at least at first). But exceeding these limits means your wiring is in violation of code. Aside from the risk you would be taking your insurance would be useless.

Is it worth it?

 

[Bondo]

Re: Run 4800W construction heater off 15A?

Ayuh,... And,... You should be using a tandem Breaker...

Just because you're using 2 breakers from opposite sides of the box, Don't mean they're off each available leg...
The legs sequence from left to right for each breaker going down the panel...
Breakers exactly opposite each other are 1 on each leg,...
1 breaker lower, or higher on each side is the Same leg...

 

[Jerryh3]

Re: Run 4800W construction heater off 15A?

Ayuh,... And,... You should be using a tandem Breaker...

Just because you're using 2 breakers from opposite sides of the box, Don't mean they're off each available leg...
The legs sequence from left to right for each breaker going down the panel...
Breakers exactly opposite each other are 1 on each leg,...
1 breaker lower, or higher on each side is the Same leg...

If they are from the same leg, the voltage between would be zero and nothing 240V would work. Also, your terminology is off. A tandem breaker provides two over current protection points in a single panel space. You a referring to a double pole breaker, which would provide 240V between the connection terminals.

 

[Jerryh3]

Re: Run 4800W construction heater off 15A?

Just take out the current two breakers,replace with a double pole, and run a new feed and put a subpanel in the garage. Problem solved.