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#46742 01/02/05 02:32 AM
Joined: Jun 2001
Posts: 141
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amp-man Offline OP
Member
Here's the situation:

A client has an electric cooktop (two-burner w/broiler) installed in a countertop outisde the house, in a covered patio. The unit is supplied by a dedicated 30 amp 120/240V branch circuit. The branch circuit cable has an equipment grounding conductor (it's a four-wire cable)

They are wondering if it'd be appropriate to use a GFCI breaker to supply the cooktop.

I say it's not required by Code, and wouldn't be a good idea, as there may be sufficient leakage current to ground (the frame of the unit) to nuisance trip a GFCI. Any GFI would have to be designed for the 120/240 circuit, of course.

Anyone have any experience with this sort of situation, or a different take on it?

Thanks in advance,

Cliff

Joined: May 2003
Posts: 2,876
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e57 Offline
Member
Electric Cook-top OUTSIDE?! Is it rated for wet/damp locations? I cant see the patio from here, but sounds like it is exposed to the elements, even if morning dew, if not blowing rain. Sounds like an electrified rust activated time bomb. GFI it, or disconnect it, I might opt for the latter. But short of that, a GFI is not a bad idea. I cant think of a requirement to do so....


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Dec 2004
Posts: 86
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Member
I agree with E57.

When the temperature drops, moisture in the air condences into the wet kind of water. That will happen inside the range too. Throw a puddle and wet hands into the equation....

Current leakage, you mentioned, is what GFI protection is for. If you have that then the current is traveling somewhere outside of the intended circuit. That's when people could get included in the path.

I don't think electric cook elements have much inductance so I'd suspect you wouldn't have nuisance tripping.

In this case, I'd say the customer's always right. Look at it this way, you wont have to try to explain to them why they have to pay for this really expensive ciruit breaker.

For me though, I like my inch and half thick porterhouse grilled over real fire.


Sam, San Francisco Bay Area
Joined: May 2003
Posts: 2,876
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e57 Offline
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Real Fire = MESQUITE! It's the only way to grill!

Maybe theres a way to covert this item to wood burning....


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Jul 2004
Posts: 625
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This thread sounds like a renegade from one of the DIY forums. The unit is a Jenn Aire, listed for outdoor use, right?

Joined: Jan 2003
Posts: 1,429
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LK Offline
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e57,

"electrified rust activated time bomb"
___________________________________________

We just had a service call for one, and he told us it was a only a year old, it looked more like 20 years, No gfci on it, but we refused to restore the power to it.

Joined: Dec 2004
Posts: 86
P
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But it doesn't need one. [Linked Image]


Sam, San Francisco Bay Area
Joined: Jul 2002
Posts: 8,407
Likes: 2
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Physis,
Quote
I don't think electric cook elements have much inductance so I'd suspect you wouldn't have nuisance tripping.
Over here in NZ, there has been a problem with protecting Electric Ranges with an RCD (GFCI).
The problem is moisture getting into the internal wiring after the appliance has been used and starts to cool down.
This moisture can cause leakage currents that will trip an RCD.
Bear in mind that this problem was found with indoor cooking appliances, so an outdoor one would tend to be worse.

Joined: Jun 2001
Posts: 141
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amp-man Offline OP
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Thanks all. Especially to solarpowered for his constructive comment.

A little background. The cooktop unit has been in place for several years and it's in good shape. The cooktop is a standard indoor one, and it's very well sheltered from exposure to rain or dew. Given that the location gets no snow, I'm not sure that the cook top is going to see much more moisture exposure than in an indoor kitchen, with a sloppy cook.

The unit is hard-wired, on a dedicated 4-wire branch circuit (i.e., has an EGC). If there is leakage current, the EGC will do what it is designed to do, and the cooktop housing will remain at zero potential. I do suspect that there may be some leakage current, which was behind my thought to not GFI-protect it.

Most old indoor electric ranges probably have some leakage current. Thanks, Trumpy, for your constructive input on that point. If I recall right, your RCDs trip at 30-40 mA, right? With leakage, the frame of the range stays at zero volts because the grounding conductor provides a path of (close to) zero impedance back to the source. No need for GFI protection.

Thanks to your comments, I realize that the outdoor setting makes things different. FYI, I am going to recommend that the unit be put on a GFI breaker, mainly because of the cooktop listing issue (i.e., it wasn't designed to be used outdoors). If the GFI doesn't hold, I may make some measurements of current on the EGC, just to see how much. At that point, it'll be the owners choice to disconnect or replace the grill.

Cheers,

Cliff

Joined: Jul 2004
Posts: 625
S
Member
Cliff,

If I gave offense, I apologize. I see that I was perhaps a bit too brief with my comment, and didn't really state what I was thinking.

The thread to which I was referring was from a lady who was about to hire an EC to install her new Jenn Aire outdoor cooktop. I was merely wondering if you were the EC she's hired, so that I could connect the two threads together, if they were indeed connected. I suppose that "renegade" was a bad choice of words on my part; I do that sometimes. [Linked Image]

[This message has been edited by SolarPowered (edited 01-04-2005).]

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