gas furnace OK on a GFI circuit?

In brief, is it OK for a gas furnace to run off a GFI circuit?
We have a gas furnace that's about 20 years old in the basement. (It also has a more recent central A/C unit coil on it.) The furnace is on a 15 amp circuit. The cable to the furnace runs through a junction box that has a duplex outlet. (The only things on this circuit are the furnace and this outlet.) While it is grandfathered under the local electrical code, code now calls for a GFI outlet (or circuit) and we are installing one.
Is it OK to run the furnace _through_ the GFI outlet or should we bypass it? I know that some things don't play well with GFI circuits, such as some fluorescent lamps. What about gas furnaces? Thanks. - Jesse
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Can you not wire it 'before' the GFCI outlet?
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Thanks for the reply. Yes, we can "wire it before", as you say. However, since the furnace is all metal and sitting on a concrete floor, we thought that running the furnace _through_ the GFIC would provide some safety factor in case an internal short happens in the furnace. In other words, if there would be no problem having the furnace run on the GFIC, we would prefer to do it that way. Thanks. - Jesse
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not a standard practice, and not recommended , wait till you get a nuisance trip on a cold winter night and you'll soon be wiring it up without the gfci ;-)
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wrote:

I think you're doing it the right way. Wire it to a GFI. Hell, for that matter, wire it through a Arc Fault breaker too. That should make you doubley safe. Maybe a surge protector too. Use sheilded cable low voltage wiring also with a current balanced thermostat. Oh........the mind wobbles. Bubba
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wrote:

Bubba --
In light of your suggested safety steps, do you think maybe we should go even further and skip electricity entirely, switching to a pile of wood and lighter fluid, and for ignition maybe a road flare will do the trick? We figure a sledge should be able to open a big enough hole in the brick wall to get rid of those pesky noxious combustion gases, or shouldn't we worry about those - too wobbly?
It is not a surprise that some of you experts think that there is no need for this, and maybe there isn't. The question was whether there would be a problem with the mid-1980s circuits of a furnace conflicting with on a gfi circuit. Thanks. - Jesse
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wrote:

Ok, if you really need it spelled out grade school style for you.....here goes. As a hvac expert, I wouldnt dare mess with a GFI on a furnace. Its just totally unnecessary. No electrical code Im aware of specifies something like what you want to do. Those damn things trip easily enough, sometimes without even a problem to trace. As with most heating and AC problems.....A/C's dont break down when its 70 degrees out and neither do furnaces. Take a guess when that GFI furnace will quit? Yep, you guessed it. On a Sat night while you are out of town for the week and its 5 degrees outside. Guess what kind of igloo you will come home too? Would there be a conflict? Most likely not but many new furnaces with all their electrical circuitry can be very finiky......especially when it comes to grounding and reversed polarity. Be a pioneer and go ahead and do it. What have you got to lose? We probably wouldnt have modern day flight if it werent for pioneers like the Wright brothers. Maybe we wouldnt even have electricity unless Ben Franklin werent ballzy enough to go fly a kite in an electrical storm. (Ok, I think he was just retarded to pull a stunt like that). There, does that answer make you feel all warm and fuzzy inside or did you really just piss your pants? :-) Bubba
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wrote:

Depends. Thanks. - Jesse
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wrote:

Depends??? Does that mean you really just shit your pants? Bubba
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wrote:

Gee, for a guy named Bubba, you catch on right quick. (Insert smilie here) - Jesse
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wrote:

Im sure you've heard of the saying, "You can't judge a book by its cover?" :-) The name is of course not Bubba but I certainly am astounded at a few of the village idiots it tends to attract. It makes me feel "special" :-) So special in fact that Im picturing CJT out in the middle of the highway right now in his diaper licking that window. Bubba
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And, that is the "perfect" situation. You've got no way to access anything live, and the metallic outer case is bonded to a grounding conductor. It's the same situation as with a refrigerator plugged into it's outlet next to a sink: Just have your electrician talk with your HVAC guy, and they'll work it out.
The fact that you don't have a good understanding of the application and function of a GFCI means that you probably shouldn't be playing electrician / furnace installer. "In case an internal short happens in the furnace" means that either you'll have a line to grounded conductor (neutral) current flow which will trip a properly sized protection device (breaker / fuse), or you'll have a line to grounding conductor ("since the furnace is all metal" ("sitting on a concrete floor" really has no bearing on anything) current flow which will trip a properly sized protection device (breaker / fuse).
From NFPA 70: 550.13 (B) Ground-Fault Circuit Interrupters (GFCI). All 125-volt, single-phase, 15- and 20-ampere receptacle outlets installed outdoors, in compartments accessible from outside the unit, or in bathrooms, including receptacles in luminaires (light fixtures), shall have GFCI protection for personnel. GFCI protection for personnel shall be provided for receptacle outlets serving countertops in kitchens, and receptacle outlets located within 1.8 m (6 ft) of a wet bar sink.
Exception: Receptacles installed for appliances in dedicated spaces, such as for dishwashers, disposals, refrigerators, freezers, and laundry equipment.
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Thank you for the info. And, you _may_ be right. Or, not. A few things. A licensed installer for the furnace (a swap for an oil/radiator system) installed the electrical box with a furnace cutoff switch and an outlet. At the time, that was the only outlet in the basement. The outlet was 2 pronged w/o a ground. Since that outlet is sometimes used when servicing the furnace - A/C system, we thought that it at least should be grounded.
(BTW, when another licensed HVAC person installed a humidifier on our central system a few years ago, he plugged the humidifier into this outlet - after cutting off the grounding prong from the humidifier's power cord. I don't know if the grounding prong is essential, but I think that someone thought it was.)
As for "in case a short happens in the furnace", this concern came up because about a week ago there was s sludge backup in the A/C condensate drain tube and that caused water to back up and then flow down over the furnace's circuit board (including its connection to the 120v line) and create a puddle in which the furnace was sitting. And, I discovered this by chance when I went down to the basement barefoot to get something and noticed that I was standing in that same puddle. This situation brought to mind a story in the news within the last few years (from somewhere in the US) about someone who was electrocuted by a window A/C unit. As I recall the story, the unit created a puddle on a concrete slab and the person was standing on the slab and in the puddle when somehow a short from the A/C unit zapped the guy and killed him. A breaker does not protect people in that kind of situation - and, as I understand it, that is what a GFI device is for: As long as you only draw 15amps from a 15amp circuit, if the current is going from your panel through your body and then to ground the breaker won't trip but a GFI breaker/outlet will trip. Now, the A/C story may be completely different from what might ever occur with a furnace in a basement, but to this mere civilian there are some troubling similarities.
Overall, those posting here about the GFI tripping for no reason on a freezing weekend when we are away - and they do trip mysteriously sometimes - make a good point.
Again, thanks to you and to all of the others who took the time to make suggestions. - Jesse
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There is no "may be right" about ANYTHING I wrote. "Or, not" does not enter into my post. Go fuck yourself.

He probably shouldn't have done that. That was something to ask back then.

It is. If the furnace is properly grounded, it does not matter if the thing is full of water. There will be no potential between the water and the concrete floor.
That's not what a GFCI is supposed to be used for. In the case of the window AC plugged into what was probably a non-grounded outlet, a GFCI would have saved his ass. And, application of a GFCI in a non-grounding application IS spelled out in the NEC.

Go fuck yourself.
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Gas furnace should be well grounded already. Don't bother to GFCI the power to the furnace.
--

Christopher A. Young
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Jesse wrote:

Electrical code wants the furnace on a dedicated circuit serving no other load (other than auxiliary equipment to the furnace like an air cleaner or humidifer), so technically that outlet should not be on that circuit at all. If you really want to keep it for whatever reason, however, then it would be better to not run the furnace through the GFCI. There is no real safety advantage to it for a furnace and there's the risk of nuisance tripping.
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Robert Hancock Saskatoon, SK, Canada
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