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ProGrade
ProGrade, Certified Electrical Contractor
Category: Electrical
Satisfied Customers: 565
Experience:  28+ years exp. - installation, troubleshooting, & repair of commercial, & residential electrical systems.
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I'm having trouble with tankless water heater, and a

Customer Question

I'm having trouble with tankless water heater, and a dedicated gfci breaker. Breaker trips, won't reset... with water heater completely removed it resets, but upon addition of ground line from water heater the breaker trips..
JA: How long has this been going on? And how severe is the problem?
Customer: just happened this evening, water heater installed 3 weeks ago, everything new
JA: Do you plan on doing the work yourself?
Customer: you are a bot aren't you?
JA: I'm an assistant to the electrician. I work with them to help customers like you.
Customer: yes, I do the work myself I'm extremely poor and handicapped + I live so far from a town that I can't get an electrician to come here. I'm just want to know what would make the ground from the water heater trip a breaker with no load applied
JA: Anything else we should know to help you best?
Customer: the sub box comes directly from main breaker on pole, and ground line is connected to grounded neutral bar in main box
Submitted: 11 months ago.
Category: Electrical
Expert:  Kevin replied 11 months ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) If the panel is configured as a sub-panel, the neutral bus bar must be isolated from the panel metal enclosure by NOT installing the main bonding jumper (either green ground screw or copper jumper strap at the neutral bus bar.

2) A sub-panel also requires a separate equipment ground bare which will only land bare copper or green ground wires. The neutral bus bar only lands white neutral wires on a sub-panel.

3) Remove the bare copper ground from the neutral bus bar and swing it over to a separately installed equipment ground bar.

Expert:  Kevin replied 11 months ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) If the panel is configured as a sub-panel, the neutral bus bar must be isolated from the panel metal enclosure by NOT installing the main bonding jumper (either green ground screw or copper jumper strap at the neutral bus bar.

2) A sub-panel also requires a separate equipment ground bar which will only land bare copper or green ground wires. The neutral bus bar only lands white neutral wires on a sub-panel.

3) Remove the bare copper ground from the neutral bus bar and swing it over to a separately installed equipment ground bar.

Customer: replied 11 months ago.
I think you've lost me. The only thing on the sub box is one gfci breaker for 220v tankless water heater. From the box on the pole SER cable HOT, HOT, and Ground... to sub box lugs, ground to the neutral bar, to which the pigtail from THQL-GFCI breaker is connected. 3 leads from water heater directly to the 3 lugs on breaker with ground from water heater hooked to same lug the pigtail to ground is connected to. This was working fine until today...
Customer: replied 11 months ago.
Deaf mute
Customer: replied 11 months ago.
With the load disconnected the breaker resets, but all I have to do is touch the ground line from the water heater to the ground lug, and it trips... do I have a dead short in my water heater?
Expert:  Kevin replied 11 months ago.

1) If the panel is a sub-panel, ground and neutral must be isolated. Ground and neutral are only bonded together at the main service disconnect. Since the breaker is a GFCI and the ground and neutral are bonded, this is what is causing the GFCI to trip.

Customer: replied 11 months ago.
the manufacturer of the water heater say the 3rd wire in pigtail not to neutral, but to actual ground. I don't have a neutral
Customer: replied 11 months ago.
there is a common bar in service box on pole that is connected to a ground spike...I'm connected to that common bar with the 'ground' line, and the 2 hots to the lugs on main breaker
Expert:  Kevin replied 11 months ago.

1) If you have a sub-panel, you have 2 hots and 1 neutral feeder circuit that connects from the main service disconnect to the sub-panel.

Expert:  Kevin replied 11 months ago.

1) The white curly neutral wire from the GFCI breaker terminates to the sub-panel neutral bus bar.

Customer: replied 11 months ago.
Ok, and the 3rd wire from water heater connects to breaker at same point as curly wire, right?
Customer: replied 11 months ago.
This worked fine for 3 weeks, suddenly nothing... I'm stumped that connecting the ground from the water heater trips a breaker with no load attached
Customer: replied 11 months ago.
I guess I'm screwed, I don't understand that what you are telling me is different than what has been done
Customer: replied 11 months ago.
as far as I can tell I'm connected exactly as in the diagram.... I'm lost with your difference between ground and neutral
Expert:  Kevin replied 11 months ago.

1) I assume the tank less heater is a 240 volt model. If so, the 2 hot wires from the heater terminate to a double pole GFCI breaker. The GFCI white neutral lands on the sub-panel neutral bus bar and the water heater bare copper ground or green ground wire lands on a separate equipment ground bar inside the sub-panel.

2) Is the sub-panel a main lug or a main breaker type? Do you have a neutral bus bar in the sub-panel and a separate equipment ground bar?

3) Ground = bare copper or green insulated wires only.

4) Neutral = either white or gray insulated wires only.

Expert:  Kevin replied 11 months ago.

1) Send me a picture of the inside of the sub-panel so I can see what you have?

Customer: replied 11 months ago.
Can't take the photo at night... access to box which is next to water heater is from a hatch on the roof, and I have to walk across beams like a tightrope walker to get there. Verbatim from installation instructions from manufacturer Ground must be brought to ground at the circuit breaker pannel. I've only got 3 places to connect anything inside my main service box... 2 hot lugs on a breaker, and a common bar attached to a ground spike... I'm connected to those 3 things with 3 wires that run to the sub box... how can I have a separate neutral, and ground this way I'm lost... the manufacturer shows hooking the ground wire to the same lug on the breaker as the pigtail, and my ground from main box is hooked to the bar that the pigtail hooks to. What am I missing?
Customer: replied 11 months ago.
If I hook the 3rd wire from the water heater to the bus bar it is exactly the same trips the breaker... I've never seen a breaker that could trip with no load
Expert:  Kevin replied 11 months ago.

1) Sub-panels are a combo of 120 and 240 volts. the 2 hot wires that land on the main breaker provide the 240 volts. The neutral bus bar provides 120 volts that is shared with the 2 hot wires that originate from the main panel.

2) Neutral and ground are NOT the same. Neutral is the "grounded conductor" and ground is "ground" 2 different functionalities:)

3) It is tripping because it is a GFCI breaker and the sub-panel is not wired correctly.

Expert:  Kevin replied 11 months ago.

See attached diagram:

Customer: replied 11 months ago.
ok, please tell me how I do this because as I said, 3 wires with only 3 places to connect to in the main service box (a Zinsco circa 1965) in a substandardly wired neighborhood on a remote native american reservation... someone called it 'one wire' service
Customer: replied 11 months ago.
it was temporary service in 1965... my house is literally on a gigantic plug-in and a big extension cord
Expert:  Kevin replied 11 months ago.

1) There is no such thing as a "1" wire service. You have a single phase service that is a combo of 120 and 240 volts.

I have nothing more to offer other than what I mentioned in my previous answers. I provided you with what needs to take place in order to correct the problem. Obviously, you know it is a grounding issue and that is due to the sub-panel is most likely bonded to the neutral bus bar and you don't have a separate ground bar.

I will opt out of the question and perhaps another expert here can provide a better answer. No need to reply back to me, you will be notified once another expert picks up the question.

Expert:  ProGrade replied 11 months ago.

Why is the water heater on a a GFCI Breaker? Does the water heater manufacturer recommend or require a GFCI Breaker? Or...do your local codes specify a GFCI? IF and only if answers to above are "No" AND the water pipe is bonded to the electrical service (this means a #4 ground wire is connected to the electrical service grounding all metal plumbing piping) then...I would remove the GFCI Breaker and replace it with a standard 2-pole breaker of the same rating.

Customer: replied 11 months ago.
The manufacturer requires it be hooked to the GFCI, with the ground line to an actual ground. No local codes, I'm on an indian reservation and if an electrician would travel here (for less than $500) I'd hire one, but our town is 779 people, and our only electrician died 7 years ago. Thanks to the clues given above I was able to track down a recently plugged in appliance that was shorting ground, to neutral... unplugged that and the water heater works fine. Thanks for your response.
Expert:  ProGrade replied 11 months ago.
You are welcome, glad you have hot water, thanks