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Home Brew Forums > Home Brewing Beer > Electric Brewing > Supplying power -- 3-prong range outlet?
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Old 12-01-2012, 05:54 AM   #21
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Originally Posted by ryanvp123 View Post
Well, yes, I'm fusing the 120V stuff with a 7amp fuse as well, but what I'm talking about is my 240V line going into the control panel.

Since I'm coming from a 50amp Range outlet, and all my equipment & wiring is 30amp/10gauge, I'm planning to put those inline fuses in to basically downgrade my 50amp outlet to a hard max of 30 amps, since I have no 30 amp breaker (50 amp in the main panel, 50A on the spa panel). I should just have to put a 30A fuse on one leg for that purpose, yes?
If you want to limit incoming current to the panel it should be done with a 2 pole breaker so that if one side "blows" or trips, the other side is also shut off. I believe something like this would be a better choice.

http://paneltronics.com/ip.asp?op=pr...oduct=206-083S
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Old 12-01-2012, 06:51 AM   #22
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Correct, here are the rules:

Existing 3-wire wiring is legal - it conformed to code when it was installed.
3-wire ground and neutral are the same going into the spa panel.
Ground exiting the spa GFI breaker ties to all exposed metal parts, including your brew controller panel & brew pot.
Neutral exiting the spa panel along with either hot leg is used for 120V circuits.
OK, I may have messed up the earlier post. If I understand what you are saying:

1) You can use the neutral after the spa panel GFCI for 120V circuits.
2) You cannot safely bond ground and neutral together again after the GFCI
3) You must not hardwire the spa panel, as it would then be subject to the current code and not in conformance because ground and neutral are bonded together after the main panel

So if the neutral on a 120V circuit were disconnected in the control panel, the GFCI would detect the imbalance and trip. Out of curiosity, what would happen if the GFCI were to fail under those circumstances? However unlikely, could I have a condition where my ground was carrying current as the neutral in the panel?

Sorry for any confusion here.
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Old 12-01-2012, 02:06 PM   #23
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...
So if the neutral on a 120V circuit were disconnected in the control panel, the GFCI would detect the imbalance and trip. Out of curiosity, what would happen if the GFCI were to fail under those circumstances? However unlikely, could I have a condition where my ground was carrying current as the neutral in the panel?
...
Just a suppose:
Your wiring is new, installed by an electrician with all permits, inspected and in accordance with today's code. It is a 4 wire circuit with a GFCI breaker in the mains panel.

What happens if the GFCI breaker fails?

Think about it.
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Old 12-01-2012, 04:38 PM   #24
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1) You can use the neutral after the spa panel GFCI for 120V circuits.
True, just like you can safely use neutral before the GFCI. It's the return path for your 120V devices.

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2) You cannot safely bond ground and neutral together again after the GFCI
True, if you were to bond ground and neutral together after the GFCI the GFCI would not perform correctly. With a 120V device drawing current it would trip all the time. With a 240V device drawing current it may not trip fast enough to protect you.

The GFCI senses current differences between the three legs. So, if current between the two hot sides and neutral average out with a small margin of error the GFCI stays on. This is true with 120V or 240V drawn from a 240V circuit. If the current does not average out there must be leakage to ground and the GFCI trips. The ground actually bypasses the GFCI & is used to bond all exposed metal surfaces, like your stove top or your brewery equipment, to earth ground.

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3) You must not hardwire the spa panel, as it would then be subject to the current code and not in conformance because ground and neutral are bonded together after the main panel
The spa panel is designed to add GFCI protection to a new or existing non-GFCI circuit. I could be wrong but I don't believe there is anything in the NEC making a permanent install illegal.

Quote:
So if the neutral on a 120V circuit were disconnected in the control panel, the GFCI would detect the imbalance and trip. Out of curiosity, what would happen if the GFCI were to fail under those circumstances?
If the neutral were disconnected at the mail panel and you were running all 240V equipment you would not see any difference. BUT if you were running a mix of 120V & 240V devices the 120V devices would see odd voltages and would likely be damaged. The GFCI would not trip.

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However unlikely, could I have a condition where my ground was carrying current as the neutral in the panel?
Any 120V devices will pass current back to the main panel through the ground / neutral because it's the same circuit. But after the GFCI, there will be no current on ground. If there were it would be because of an unbalance and the GFCI should have already tripped.
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Old 12-01-2012, 05:09 PM   #25
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The spa panel is designed to add GFCI protection to a new or existing non-GFCI circuit. I could be wrong but I don't believe there is anything in the NEC making a permanent install illegal.

In fact I would presume it's generally intended for permanent installation. However, I think the point is not that, the point is then NEC may well apply differently to the fixed/permanent installation than what may apply under the guise of cord & plug connected equipment.
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Old 12-01-2012, 05:18 PM   #26
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Any 120V devices will pass current back to the main panel through the ground / neutral because it's the same circuit. But after the GFCI, there will be no current on ground. If there were it would be because of an unbalance and the GFCI should have already tripped.

Maybe things would be more clear to talk in terms of grounded wire (neutral) and grounding wire (equipment ground). When just the term "ground" is used it's unclear in some cases what's really meant.
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Old 12-01-2012, 05:42 PM   #27
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Thanks guys. I do believe I understand at this point (or now I know enough to be really dangerous).

I was under the impression if doing permanent wiring it would have to conform to current code (and subject to local inspections, etc.), and that bonding neutral to ground is verboten except at the main panel.

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Old 12-01-2012, 06:18 PM   #28
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Maybe things would be more clear to talk in terms of grounded wire (neutral) and grounding wire (equipment ground). When just the term "ground" is used it's unclear in some cases what's really meant.
I wouldn't think of the neutral as a ground. When there is a lot of current running through it, there might very well be an AC voltage present (I*R drop across poor connections or wire resistance).

Also, if there is a GFCI upstream on the ckt, the neutral isn't directly tied to earth ground anyway. You might not always know if the ckt is GFCI protected.

Green is ground. White is neutral.
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Old 12-01-2012, 11:01 PM   #29
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Thanks guys. I do believe I understand at this point (or now I know enough to be really dangerous).

I was under the impression if doing permanent wiring it would have to conform to current code (and subject to local inspections, etc.), and that bonding neutral to ground is verboten except at the main panel.
Any additions must conform to current code. If the house wiring had to conform to current code when a wiring addition was done, most houses in this country would have to be rewired when something was added. And adding this spa panel to a unused stove circuit is adding to existing wiring.
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Old 12-01-2012, 11:17 PM   #30
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So the spa panel, going from 3 wires to 4, would conform to the current code? I thought not, because are not neutral and ground bonded together in the spa panel? I was not referring to the preexisting wiring.

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