how do I hook up a ground wire to my new furnace when my house wiring does NOT have a seperate ground wire?

You don't have to call the heating company, any licensed electrician can install a grounding conductor or new wiring from the service panel to the furnace.

If a heating company installed your new furnace, they are responsible for making the correction connections to electric power. I get the impression you installed it yourself.

The National Electrical Code requires new wiring installations to have grounding conductors, and new permanently installed equipment to have connections for a grounded conductor if the equipment is connected to the electric service panel.

Most cities in the United States have adopted the NEC as a basis for their own electrical codes, and often add rules and stronger restrictions of their own. They also allow buildings with electrical wiring that predates that requirement to not have grounded conductors, as long as no substantial changes are made to the wiring. They might require that equipment that is designed for connection to grounded conductors have to be properly grounded.

Using the cold-water metal pipe for the ground connection is no longer adequate, in some areas it is not acceptable because the metal piping might be connected to plastic piping and hence you will not have a ground connection at all, or the metal piping in one section is galvanized steel and in the other section it is copper - I have this situation - and in this case the steel is separated from the copper with a dielectric union, which is an insulator, which interrupts any grounding.

Many cities require the natural gas pipe to be grounded on the customer side of the meter where the pipe enters the house, with a separate grounding conductor back to the service panel.

The Carrier furnace is designed to meet those equipment requirements.

The grounding conductor is usually called the ground wire and is bare or has green insulation. It is for electrical safety, in case there is a wiring fault inside the furnace, the stray or excessive current flow will go through the grounding conductor and the furnace metal parts will not be electrically energized - what people colloquially call "hot". This is a personal hazard as anyone who touches any exposed metal parts could be shocked. The grounding conductor also ensures that the stray current flow from an electrical fault will not go through the metal piping for the gas lines.

You mention an igniter, so I assume you have natural gas or propane service, and the only need for electric power is for the igniter and the blower motor(s). Usually that is 120 VAC. The black wire is the energized wire and is called the hot wire and goes to the circuit breaker or fuse in the service panel. The white wire is the grounded conductor and is called the neutral and goes to the neutral bonding block in the service panel. The white wire carries the same current as the black wire.

Unfortunately, sometimes the wiring is not done correctly and the black and white wires are swapped You should use a voltmeter or multimeter to verify the white wire is indeed correctly wired.

So, you cannot use the white wire for grounding purposes.

I do not know why the igniter did not work when you wired the ground connection to the white wire, unless there was some kind of GFCI (Ground Fault Circuit Interrupter) within the control for the furnace. These circuits are not difficult to include in the controls.

A GFCI works by measuring the current flow in the hot wire and the neutral wire (both inside the unit). These two currents should be the same, current in the black wire equals the current in the white wire. If there is an imbalance, often as small as 5 milliamperes ( 0.005 amperes or the current required to light a tiny half-watt light bulb or neon lamp), the GFCI will trip its relay and remove power from the circuit.

My theory here is that since you had connected the green screw to ground some small current flowed out it rather than through the neutral connection. But it is not a good theory.

You did not say anything about having to "reset" the control, but a self-resetting GFCI (due to power cycling) is possible. That would explain why it worked when you removed the jumper between the green ground screw and the white wire. But I have not read anything about such circuits as it has been quite a few years since I have kept up with changes to the NEC and equipment safety design.

So the quick answer to your question is : the furnace will work properly without a ground connection back to the service panel. There are probably millions of furnaces installed in this country - one in my father's house, for example - that do not have a grounding conductor connected to the furnace.

But it will not be considered electrically safe by your insurance company. If there is any problem caused by the furnace that results in an insurance claim, they could refuse to provide coverage because the furnace was not properly grounded.

TonyRB

Saturday, November 28, 2009 4:30 am CST

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Tony RB has it right. But he wrote a damn book. Just get a new 14-2 with ground from your furnace to your panel. Wire the ground wire and neutral wire into the neutral bar.

On a side note. It wouldn't hurt to put ground rods down. Code requires (2) 8' in length, all the way down, six foot apart, and connected to a number #6 AWG copper. This should go back to the neutral bar as well.

How To Wire A Furnace

What you need to do is Take the Green Wire from the furnace and attach it to a cold water pipe. This will give you the ground. Just make sure you scrape or sand the area around the pipe so you have a good connection. You can use a hose clamp to secure the wire. Also you need to use a heavy duty wire ( about the same as your power wires) .

A neutral wire is to complete the flow of electricity! Dont go playing with that! Personally, I would just leave it. Normally, it is attached to a ground in your box. If your conduit is metal, you can attach the green to it. It should be grounded. The way to create a real ground is to hammer a 5' copper rod into the earth leaving enough out of the ground to attach to. You attach to it with an "inline clamp" I would run that to the body of your electrical box.

Take caution when driving anything into the ground such as a five foot stake, you might hit something such as a waterline/sprinkler system, wiring, cable, etc.. Call Miss Digs first. They'll come out to check if there's anything buried before shoving a stake or post in the ground and it's free. Or it use to be...

Screw the The National Electrical Code And screw regulations! I am so sick of these safety codes that pretend to keep us safe, But all they do is make us poorer! If you know enough about electronics to fix or install something, Then you are smart enough to know how to avoid wiring that will cause fires! And this emissions crap is just a BS scheme created by politicians involved in the wall street mafia!

run a bare wire from the furnace to the out side

drive a steel or copper stake in the ground and attach the wire to it,

color means nothing if they are backwards. it sounds like you made the metal frame of your carrier hot don't hook up ground to H2O pipe unless it has an earth grounding rod wired to it also. or you may experience a new sensation in shower when the water in drain completes a ckt through you. path will flow through a light bulb then through white wire to water pipe. then complete the journey to earth through your a**. in most electrical panels the white and ground go to the same lug bar. mobile homes have separate lug bars. but always grounded at power pole with same conductor simply pound ground rod. run # 10 awg ground to neutral lug bar and to cold water pipe. you may use whites as neutrals or grounds and splice as such. not up to code though until u run a ground wire from panel to appliance. a breaker should trip if black and white are reversed.

Read electrical inspectors post over and over. If you are talking about a fixture then you should bye a fixture listed for use with no equipment ground.