# Grounding or line polarity fault



## zappa (Nov 25, 2011)

Others can help you better with your furnace problem. I can tell you not to worry about the lack of ground rods causing this problem. A metallic water pipe is a fantastic (primary) ground especially if you have city water.


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## yuri (Nov 29, 2008)

I have had those ground wires to a water pipe become loose or corroded. May have to redo it.


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## beenthere (Oct 11, 2008)

Has any other electrical work been done in the last 6 months or so.


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## michaelcherr (Nov 10, 2010)

beenthere said:


> Has any other electrical work been done in the last 6 months or so.


Yes, lots of work. Added a fair few circuits and a sub-panel. 
The furnace has it's own dedicated circuit. 
I did cut the wire running to the furnace and added a lightswitch as a shutoff to help me turn on/off while doing diagnosis, but again I verified correct polarity at the furnace (and temporarily reversed polarity as a test) 

It's either an issue with the grounding, or the fault code is wrong. 

I'm probably going to drive two ground rods for good measure, but I doubt that will solve my issue.


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## yuri (Nov 29, 2008)

Post a pic of the circuit board and where it attaches. Goodman/Amana had a problem with some where the plate which the board attaches to was attached to the fan and the mounting screws came loose and it lost ground. Had to put new and larger screws in the plate. Also had to run a green #14 wire from that plate to the ground wire coming into the furnace.


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## beenthere (Oct 11, 2008)

Good chance that something you wired is not grounded correctly. Or is bleeding current back through the ground.


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## Bob Sanders (Nov 10, 2013)

The igniter should be solidly grounded to the furnace. I've had issues in the past with corrosion on the igniter ground (which throws a code 6)


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## michaelcherr (Nov 10, 2010)

The ignitor seems solidly grounded. 
The board is connected to its mounting bracket. 
The wiring diagram shows one grond wire from the board that (assuming the plastic quick connects are solid) is screwed to a bracket near the burners. This is where I connected an extra ground wire to a nearby pipe. 
I saw that the inducer motor looked a bit corroded/where it's ground attches to the metal housing. I clipped that wire and grounded it more solidly. 
The ignitor seemed solidly attached to theetal housing. It's two wire, so I assume that is hot and neutral (no ground)


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## yuri (Nov 29, 2008)

Beenthere may be right about the house wiring. That is a VERY rare scenario you have. I had a house once that was blowing the transformer in the furnace and they had other problems with the TV etc due to some strange wiring. Try posting in the electrical forum on our home page for more hep.


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## michaelcherr (Nov 10, 2010)

Wouldn't wiring issues be ruled out since I tested hot to neutral, hot to ground, and neutral to ground inside the furnace? 

My furnace guy is back in town, going to give him a call.


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## yuri (Nov 29, 2008)

Current may be bleeding <<back thru the ground to the furnace.

Not sure how to check for that. Beenthere may know or try the Electrical forum. There are more Pro Electricians there with lots of experience.


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## michaelcherr (Nov 10, 2010)

yuri said:


> Current may be bleeding <<back thru the ground to the furnace.
> 
> Not sure how to check for that. Beenthere may know or try the Electrical forum. There are more Pro Electricians there with lots of experience.


I could test that by powering the furnace with GFCI protected circuit. If any current is bleeding through to ground, the GFCI will trip. 
That's how I test old motors for bad windings shorting to the housing.


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## sidejobjoe (May 30, 2014)

I would think twice about putting extra ground rods in. I'm not an electrician but pretty sure code requires there can only be one ground for the electrical system in your house.... sounds like you've got that covered with your water pipe ground. 

Now you may need to bond your furnace/gaspipes etc... together but that is a different story.

Having multiple ground rods can be very dangerous as it provides 2 references to ground/neutral. 

Mike Holt has a tons of info on this which I've found to be very informative.

https://www.youtube.com/watch?v=M3lX4XtlYXk&list=PLv5IcVLCg9o1YeCyAdxWx5vLmCtFbeR8-


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## michaelcherr (Nov 10, 2010)

sidejobjoe said:


> I would think twice about putting extra ground rods in. I'm not an electrician but pretty sure code requires there can only be one ground for the electrical system in your house.... sounds like you've got that covered with your water pipe ground.
> 
> Now you may need to bond your furnace/gaspipes etc... together but that is a different story.
> 
> ...


I think you are getting confused with tying neutral and ground together. 
The main panel is the only place neutral and ground should be tied together. 
Connecting the main panel's ground to both the water pipes and a ground rod is code compliant, safe and standard practice. 
In my area water pipes are not an acceptable means for grounding (for new construction) but the water pipes need to be connected to ground if metal (use jumper to get both sides of meter) 
The water pipes need to be connected to ground for safety, in case they get energized, in which case they would complete the circuit and blow a fuse/trip breaker.


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## sidejobjoe (May 30, 2014)

Not exactly and maybe I don't understand it but.... I think NEC says you can have as many ground rods as you want as long as they are bonded together. 

I understand what you are saying but... as I understand it.... I can not drive a ground rod on the opposite side of the house and connect that to my water/gaspipes since they could possibly be connected to equipment ground at the panel. 

Interesting discussion but we are probably getting off the rails for the forum


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## TimPa (Aug 15, 2010)

for a furnace ground test, connect one end of your ohmmeter to the water pipe connection, and the other to the furnace ground connection. you may need some extra wire and a helper to accomplish this. you should read next to zero ohms. then test to the controller ground as well.

recommend you do this with furnace power off.

water pipe (copper) is no longer acceptable as the only source of earth ground, since many municipalities are now converting to plastic outside the home. used to be they wanted min 10' of copper outside. when electrical services are upgraded, ground rods are required in most areas if not all.


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