GFCI protection of a 240V 40A stove in a dwelling

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marmathsen

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Seattle, Wa ...ish
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Can anyone out there speak from experience about installing GFCI protection on a standard residential electric stove? Have you had issues? Do you remember what brand or even what model it was?

We recently did a service change on a boat house in Seattle. NEC (553.4) requires GFCI protection of the entire service or every individual circuit. We opted to protect at each circuit breaker. A couple issues came up that we were able to resolve that were related to an old heater and some bad makeup. The one issue that remains is the stove.

In troubleshooting the stove we've determined that all of the cooktop elements work fine as well as the broil element. The problem is only with the bake element where it trips the GFCI immediately. We recommended that they have an appliance repair tech come out and repair it. When the tech came out they couldn't find anything wrong so they called Whirlpool. Whirlpool said it's working properly and it's no surprise that it trips a GFCI and they have no solutions since they expect that ALL OF THEIR STOVES WOULD TRIP A GFCI. The general contractor called their appliance supplier and they got the same response that no stove out there would work on a GFCI. WTF?

What are other people doing on boat houses currently?

Furthermore, as I understand the 2020 NEC, 210.8(A) will require GFCI on many land based stoves anyway since they are within 6 feet of a sink. So are the appliance manufacturers just woefully behind the 8 ball on the 2020 NEC?

Am I missing something?

Are the appliance repair tech and appliance suppliers missing something.

Rob
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
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Is this a 3-wire or 4-wire circuit, and are it and the stove wired correctly?

Beyond that, it's really between the customer and the appliance maker.
 
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hillbilly1

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The heating elements inherently have leakage due to design, some more than others. Isolating the elements from ground would solve the problem, but would introduce a shock hazard if the element fails. Manufactures will need to redesign, or get that silly new code requirement removed.
 
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marmathsen

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Seattle, Wa ...ish
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hillbilly1 said:
The heating elements inherently have leakage due to design, some more than others. Isolating the elements from ground would solve the problem, but would introduce a shock hazard if the element fails. Manufactures will need to redesign, or get that silly new code requirement removed.
Click to expand...

The Broil and Bake elements are the same wattage but look to be different part numbers. Maybe just a slight variation in manufacturing makes the bake element trip the breaker but the broil is fine.
 
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marmathsen

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Seattle, Wa ...ish
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Electrical Contractor
ptonsparky said:
Have you megged the element and or looked for faults?
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I'm hopeful that the appliance repair tech did that. I think what gets me is that the manufacturer is saying that they expect any of their stove elements to trip a GFCI. Maybe like hillbilly1 mentioned, they are designed to have leakage.

hillbilly1 said:
The heating elements inherently have leakage due to design, some more than others. Isolating the elements from ground would solve the problem, but would introduce a shock hazard if the element fails. Manufactures will need to redesign, or get that silly new code requirement removed.
Click to expand...
 
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hillbilly1

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marmathsen said:
I'm hopeful that the appliance repair tech did that. I think what gets me is that the manufacturer is saying that they expect any of their stove elements to trip a GFCI. Maybe like hillbilly1 mentioned, they are designed to have leakage.
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Don’t know of an appliance repairman that would carry a megger! LOL! Could change the element to see if that works.
 
Jraef

Jraef

Moderator, OTD
Staff member
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San Francisco Bay Area, CA, USA
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Might be the controller. For Broil, it's just On the whole time, but for Bake, it might be controlled by an SSR or something that has leakage current to ground in the firing circuit. That would explain why they say that none of their ovens would work behind a GFCI.

Secondary issue: Something you might have missed in 553.4 of the 2017 code, which is what your state follows...
The requirement for "Ground Fault Protection" for floating homes is for ground fault protection on the Main, which can be set for 100mA (a.k.a. EQUIPMENT ground fault or GFPE), and the alternative is to have "ground fault protection" on each individual circuit. IT NEVER SAYS GFCI!

GFCI means 4-6mA, as opposed to 100mA. That is a HUGE difference when it comes to things like leakage current...

I have friends that live on a houseboat on Lake Union in Seattle, they made the same mistake, I set them straight and everything works now.
 
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marmathsen

Senior Member
Location
Seattle, Wa ...ish
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Electrical Contractor
Jraef said:
Might be the controller. For Broil, it's just On the whole time, but for Bake, it might be controlled by an SSR or something that has leakage current to ground in the firing circuit. That would explain why they say that none of their ovens would work behind a GFCI.

Secondary issue: Something you might have missed in 553.4 of the 2017 code, which is what your state follows...
The requirement for "Ground Fault Protection" for floating homes is for ground fault protection on the Main, which can be set for 100mA (a.k.a. EQUIPMENT ground fault or GFPE), and the alternative is to have "ground fault protection" on each individual circuit. IT NEVER SAYS GFCI!

GFCI means 4-6mA, as opposed to 100mA. That is a HUGE difference when it comes to things like leakage current...

I have friends that live on a houseboat on Lake Union in Seattle, they made the same mistake, I set them straight and everything works now.
Click to expand...

Seattle has actually amended 553.4 to require maximum 30 mA protection. I looked into getting a 30 mA breaker and it was pretty price prohibitive ($426). That might be the solution ultimately but I was reluctant to special order it and risk it not solving the issue.
 
tortuga

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
marmathsen said:
Seattle has actually amended 553.4 to require maximum 30 mA protection. I looked into getting a 30 mA breaker and it was pretty price prohibitive ($426). That might be the solution ultimately but I was reluctant to special order it and risk it not solving the issue.
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Whoah what kinda panel do you have?
ptonsparky said:
Interesting. If I can scrounge up a GFCI breaker, I'll give it a try at home.
Click to expand...
Ditto I think I have a old 50A hot tub disconnect around somewhere.
 
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