20 amp Gas Furnace Plug + Fridge ??
I had to plug a small 7amp fridge into the single plug outlet that powers our gas furnace, because there was not enough power on the garage circuit to run everything without tripping the GFCI. So, I have a 12AWG plug splitter coming out of the single plug 20 amp outlet that is typically dedicated to the Carrier gas furnace. I can’t tell how much the furnace pulls, because i can’t find a serial/model number, but from what i can tell they are fairly efficient. this one is less than 15yrs old, maybe even as new as 8-10. should this be an okay solution to get by until i get an electrical plan to beef up the supply in the garage, or should i worry about the house burning down? I’m in So-Cal, so the heater doesn’t run that often (today its 73), but i would like for it to be available if necessary.
thanks for the help,
-mike.
Replies
As far as I know (at least here in Canada) the only reason a Gas Furnance is on it's own circuit is so no other shorting appliance can kill power to it by tripping the breaker. Hence not a good idea to plug something else in, but unlikely to do any harm in the short term. Although, again in Canada. the Furnace is hardwired to a switch so there is no way to plug anything in anyways.
The biggest danger would be a breaker popping if both units attempt to start simultaneously, but even then you're unlikely to pop a breaker.
You should look for a better permanent solution, but as a temporary solution I see no problem with doing what you describe.
happy?
when you plugged in the fridge to the other garage circuit, did you pop a GFCI breaker in the panel, or a GFCI receptacle ? If the latter, it's not overcurrent, it's potentially a ground fault.
Also FYI, section 422-12 of the NEC (1999, anyway) requires that "central heating equipment" be supplied by an individual branch circuit.
Also, I don't think a cord and plug connected gas furnace is legit, either. (I have a book that references ANSI Z21.47 on that subject, but I don't know more than that).
Edited 11/28/2005 5:39 pm ET by r
I do not see anything in the NEC that would prevent having the gas furnace plug and cord supplied, as long as the nameplate rating did not exceed the rating of the cord/plug. I have done this several times for people to have the ability to plug the gas furnace into a generator. You cannot break the ground (bonding) to the gas piping, assuming it is metal . The plug can also act as the disconnect, although a switch would be the perferred method for a furnace. One can also cord and plug connect dishwashers, diposals, trash compactors and gas ranges.Industrial uses and ANSI specs may be different.Frank DuVal
This is from Mullen, "Electrical Wiring Residential", 13th edition, page 402: In the section headlined "Cord and Plug Connection Not Permitted", he writes, "A key requirement, oftentimes violated, is that flexible cords shall be used only 'where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection' [1999 NEC 400-7(a)(8)]. Certainly the gas piping and the size of a gas or electric furnace do not allow for 'ready removal' of the furnace".
I suppose you could challenge his statement by saying that if the manufacturer provides for the cord and plug connection of their furnace, they must think it's 'designed to permit ready removal'. And again, I don't know anything about the ANSI standard that prohibits this, or its rationale.
OK, let me correct that statement I made. It does appear that NEC section 400.7 and 400.8 could prevent cord connected furnaces. I'm sure the intent is to prevent a 10 foot cord on a furnace going to an outlet across the room. Hence the restrictions on cord length for disposals and dishwashers. Frank DuVal
it was a plug type GFCI, and it did not pop right away. if something else was turned on, or if both units cycled at the same time it would set it off. its a standard 15 amp circuit, so it can't take the loads from both, plus a couple other small things that are connected to that circuit.i've never seen a hard wired furnace in any of the homes i've lived in... and the last two were both under 15yrs old. can anyone else confirm if this is true for homes in CA?
"its a standard 15 amp circuit, so it can't take the loads from both"
I'm not saying it couldn't be a 'nuisance' trip. But I am not aware of any GFCI's that trip on overcurrent - just ground faults.
I agree that the furnace is probably small enough load that for a temporary measure this is OK.About the furnace being cord and plug connected remember that there are local/state codes that are either written on their own or adopt a national code WITH LOCAL CHANGES.This might be one of them.For example see the other thread about emergency shut switch on furnaces. There are also local practices that keep happening because that is the way that they saw it done before. And inspectors will even require them until some ask for them to show it in the code and that is when they find out that there is no requirement to do that way. Often the inspectors aren't questioned because the changes are minor and the person doesn't want the inspector to start "looking for other problems".That might also be why you have the cord and plug connected furnace.As for your problem with the GFCI. They trip when the difference in current between the hot wire the neutral wire is 0.005 amps or more. And that is for all wires and loads that are connected to the GFCI and downstream receptacles. The load current does not matter. The breaker will trip on overloads, but the GFCI. Refigerators in particular are know to have leakage currents that will trip GFCI. However, that is not a safety problem as they are ground and any minor leakage current flows through the equipment grounding circuit.The code allows for dedicated receptacels that are not GFCI for equipment that is not normal moved. Among other things that include refigerators, freezers, and sump pumps. Althought those things might be used a basement for garage where receptacles otherwise need GFCI those dedicated receptacles do not.In your case you might need to have a new circuit run. But is also possible to install a non protected receptacle on the existing circuit. One way of doing that is to rewire the existing GFCI it it does not protect the downstream receptacles. Then recplace all of the existing downstream receptacles with GFCI ones EXPECT the one for the refigerator.