HVAC tech needs help

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Daltex

Member
Location
Dallas TX
Installing a new furnace at a lake house in the boonies. New dedicated 12/2 NM run by electrician before I arrived. Finished install and computer in furnace was acting up so after an hour of trouble shooting I checked the ground and there was none.

Inside panel everything looked clean. No neutral double taps but buss bar was full but noticed an equipment grounding bar with one single ground landing on it. Traced back and saw it was for new furnace circuit. Tested continuity with neutral buss and it was open. Tested various KO clamps and screw holes and the panel isn't bonded. Called electrician to meet me and next day he explained how "this system is set up". There is 200 amp 3 wire feed to meter and attached pass through panel that runs 3 wire feed to two different main panels in house. House used to have two separate areas and even though now connected they are only bonded by the three wire feed. The feed tees off for each part of house. He said because of this and because the house was built in the 50's that its grandfathered in and safe.

I know now bonding and grounding is complex but it still doesn't seem safe so I called another electrician out and another day later he said basically the same. He told me if the ground was a problem for me he would switch the EGC with another one off the main buss. There is limited resources out here and I can't spend another week dealing with this.

in my business you can't make a recommendation over the phone so I understand if no one can give me advice but I was wondering if there is any issue with bonding the neutral buss with the panel. It makes perfect sense to me because it would also bond the panel and I can't fathom a reason why the NEC would allow the panel to be unbonded.

FYI I do understand current code would be to have a four wire run to each panel and have neutrals and grounds unbonded at each panel. Only bonded at the main panel but the pass though panel and two licensed electricians have me scratching my head.
 

Mgraw

Senior Member
Location
Opelousas, Louisiana
Occupation
Electrician
The furnace will not work without the ground wire being bonded to the neutral somewhere. If there is a ground bar in the electrical panel then it probably needs to be bonded there.
 

mgookin

Senior Member
Location
Fort Myers, FL
The furnace will not work without the ground wire being bonded to the neutral somewhere. If there is a ground bar in the electrical panel then it probably needs to be bonded there.

Are you saying the computer is looking for that ground and locking the furnace out since it can't detect it? (we don't have furnaces here)
 

Daltex

Member
Location
Dallas TX
The furnace will not work without the ground wire being bonded to the neutral somewhere. If there is a ground bar in the electrical panel then it probably needs to be bonded there.

It is now bonded to a ground bar in the panel but that ground bar isn't bonded to the neutral at any point due to the panels neutral buss not being bonded to the panel. The other grounds are on the common neutral bar but the bonding screw to bond that to the panel is absent like a sub panel setup but there is only a 3 wire feed so no connection from panel/new ground bar to service equipment.
 

Daltex

Member
Location
Dallas TX
Are you saying the computer is looking for that ground and locking the furnace out since it can't detect it? (we don't have furnaces here)

Yes. I assume it references ground for some reason but installation instructions clearly state a separate ground is needed and can't be used with a non grounded but GFCI protected circuit.
 

Daltex

Member
Location
Dallas TX
I'm thinking since there are two panels after the pass through panel at the meter that this could be a parallel setup that an electrician just failed to add bonding screw to neutral bar. I'm licensed to make electrical connections and such but changing a panels bonding is beyond my comfort zone. I just want to make sure everyone is safe and the furnace works. Right now I'm most afraid of a panel that isn't bonded but there may be a reason for it. Seems very dangerous.
 

kwired

Electron manager
Location
NE Nebraska
Are you saying the computer is looking for that ground and locking the furnace out since it can't detect it? (we don't have furnaces here)
Most flame proving sensors need a ground path to work properly, it is likely more trouble with detecting a flame causing a lockout more so then not having a ground causes "computer trouble".

It is now bonded to a ground bar in the panel but that ground bar isn't bonded to the neutral at any point due to the panels neutral buss not being bonded to the panel. The other grounds are on the common neutral bar but the bonding screw to bond that to the panel is absent like a sub panel setup but there is only a 3 wire feed so no connection from panel/new ground bar to service equipment.

Those you talked to may be correct that the three wire feed to the panel(s) is "grandfathered", but not bonding the cabinet at all is still wrong. If three wire feed is allowed to remain, then the neutral would be the only choice of bonding the cabinet.

Now if there is only old circuits with no EGC's in any of them - you likely do have a violation by adding anything new to that panel, because anything new (since about 1962?) would need an EGC.
 

Daltex

Member
Location
Dallas TX
Most flame proving sensors need a ground path to work properly, it is likely more trouble with detecting a flame causing a lockout more so then not having a ground causes "computer trouble".

i know what your talking about but this furnace won't ever attempt to fire and the stat displays a fault code stating improper electrical supply before there is even a call for heat.

Those you talked to may be correct that the three wire feed to the panel(s) is "grandfathered", but not bonding the cabinet at all is still wrong. If three wire feed is allowed to remain, then the neutral would be the only choice of bonding the cabinet.

Now if there is only old circuits with no EGC's in any of them - you likely do have a violation by adding anything new to that panel, because anything new (since about 1962?) would need an EGC.

Thanks for the reply because I felt it was wrong to not bond the cabinet but due to the complexity of bonding/grounding I defer to the electrician all but this time. It just didn't make sense.

I will tell the homeowner that he needs to insist that an electrician fix this issue but I'm not the one that ran the new circuit so will let the homeowner know that it isn't code and as long as the cabinet gets bonded and the furnace gets its ground my end will be good to go but he may want his electrical system evaluated. Problem is him getting good advice.

I appreciate the the good advice available here!!
 
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