HVAC Electrical Issue: Current Leakage from Furnace

[Averagesupernova]

I do have a significant clue though: I opened the furnace's main ON/OFF switch today to have a look and I measured the ground wire with my ammeter and there was current!
I went back to the main panel to investigate and when I separated it out from all of the other bare ground wires that it was touching... there it was. Net current on that wire and that wire alone.

Well in the past you have said you have had the imbalance without including the ground wire. Now you say you have current on the ground wire. Is this current still there when you turn the breaker feeding the furnace to off? In the past you've said the imbalance went away when turning the breaker off. This on/off switch you refer to, I assume it is mounted on the furnace. Do you still have ground current after shutting it off?
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The fan is always running you are right.
The fan cannot be turned off at the thermostat either.

The only way to get the fan to go off is to shut power for everything down at the thermostat.

Concerning the above, it makes no sense. For several reasons. Both paragraphs together contradict each other. Also, according to the diagram you drew as well as the diagram from the furnace, if the circuit to the furnace is live, the blower will run. Nothing from the thermostat should be able to shut it off.

 

[UrbanFarmEngineer]

Yes I just discovered the current on the ground wire today when I opened the ON/Off switch. I hadn't known about it before. The main ground wire is from the main line and it is wound really tight inside so I couldn't get at it (and never thought about it either). The switch is mounted to the ceiling on a piece of wood. I just replaced the parts and it did not make a difference.

About the fan, when I set the thermostat to OFF the fan powers off. The fan runs constantly on Heat or Cool. I have no control over the speed and FAN setting does not work, I.e., I can't put the FAN on via the thermostat.

 

[UrbanFarmEngineer]

and no ground current after turning the switch off.

 

[Averagesupernova]

Ok. Well something doesn't add up if you can control the fan from the thermostat but that shouldn't change the current imbalance issue. I assume the imbalance current is close to the same as the ground current. Can't expect them to be identical as there could be other paths back besides the ground wire. If you suspect the blower motor, which you have in the past, wrap the clampmeter around both the hot and neutral feeding the blower motor. Only those two. Watch for an imbalance.

 

[Averagesupernova]

One other thing. Your diagram shows a block that all the neutrals connect to. This cannot be connected to the chassis. If it is this would explain your imbalance.

 

[berkeman]

Thread is closed temporarily for Moderation...

 

[berkeman]

After re-reading all 3 pages of this thread, I'm going to leave it closed. It is just too difficult to try to diagnose something like this long-distance over the Internet.

@UrbanFarmEngineer -- Please try to find an EE or HVAC service professional in your area to help you figure out these issues.

EDIT -- Thread reopened temporarily for summary post by OP.

 

[UrbanFarmEngineer]

Hey Everyone:

Thank you to all who commented on the original post with how to help. I thought you may be interested in knowing how it all turned out.

It took me a while to wrap my mind around what you guys were telling me but I am happy to report that the issues are diagnosed and solved. I got lots of good advice from all of your posts and from your PMs. In addition: I got two amazing book recommendations earlier today that I am looking forward to diving into to establish a foundation in the principles of electrical circuits so I can better keep up with what you are talking about because as terrible as the furnace experience has been it made me love learning about circuits.

So here is what's going on with the furnace:

1) Open/Faulty Limit Switch: and it's the kind that can't be reset manually. This was disovered thanks to the person who recommended I do dead testing which was @Guineafowl and I believe @Averagesupernova

2) Short to Ground in the wires leading back from the blower fan: they were not bundled/protected properly and kept rubbing up against a somewhat sharp piece of metal that extends out from the blower fan housing for some reason. A few of wires had scrapes in the insulation and exposed copper. Thank you to the people who PMd me to do visual inspections of the wires after a load and not before, since everything was still working.

3) Unprotected Power Line: Flexible cord from condensate pump inserted into same wire access point as main power line (BX). There was an AntiShort on the BX that protected the main power line conductors but the sharp side where the BX was cut sliced into the condensate power line and gouged right into the conductors. It's hard to see in the pics but you could see copper.

At Present: net current on dedicated main power line to furnace = 0 mA. Mission Accomplished.

Why did I try to fix it myself? When the local gasCo gave me notice of two electrical infraction and I called the installers they came to do an electrical diagnostic and repair. They showed up with no multimeter, no instruments of any sort. Not even a visual inspection. They did not even open the jBox behind the cords entering the cabinet in the picture below to examine the black cord which is visibly damaged! The guy just put a piece of tape over it from the outside and said, "furnace runs, means there is nothing wrong.". And there was nothing that I could say to him to make him do anything more. He just got really mad.

Researched installation company: No natural gas licence, not affiliated with any sort of electrical licence, no permit applied for when they installed the furnace (which was less than a year ago).

INSTALLERS' SOLUTION TO SHORT TO GROUND INFRACTION:

A little blurred:

 

[Guineafowl]

Shows the value of a good visual inspection (with power off!)

Or, “more is missed by not looking, than not knowing”.

I’ve found that sort of fault before by running an IR test, and watching the display as I wiggle wires, focusing on entry glands and contact points.

 

[berkeman]

Thread is reclosed.