3 wire 240 outlet to spa panel wiring question

[ajdelange]

Has anyone got a 240v GFCI to work properly when wired HHG?

Yes, I have them in my panel and have connected 220V pump motors and and arc welders (both HHG). They don't trip the GFCI.

There's a lot of confusion here and at the Mike Holt forums. It is clear that when wired for 240v you do not need a neutral on the load side (see wiring diagram on p11 from Square-D link below). The manufacturers state that you need neutral on the line side for the GFCI's "test" button to work (see both links).

The test button works by returning some current from one of the load side H terminals through a path other than the other load side H or N terminal. It can connect either load side H to either the opposite line side H or N. Apparently they have chosen to connect to N. OP could connect the breaker's white wire to the feed G in order to have the test button work. It is only connected to G when the test button is pushed and as such, I suppose, might not constitute a code violation as long as the breaker's N terminal is not connected to anything. Or he could wicker his own test button in which a resistor is connected between load side H to G through the button contacts.

It's not clear to me if the GFCI will function without the "test" button,..

Only reason it wouldn't would be because of device failure which is what the test button is there to detect.

... but without it you have no way to know.

Just so.

It's also not clear if the GFCI "test" button would work if you tied the ground wire to the neutral bus in your spa panel.

That would depend on whether you bond it on the line or load side. If you do it on the line side then it should work. Imbalance (0-sequence) current flows back through the core except in the case of a fault to ground in which some of it doesn't. OTOH if you were to bond on the load side any imbalance current would return partly through the ground wire.

If it does you'd be using an uninsulated ground wire as the neutral. Even if it does, it's certainly not to code, and I wouldn't do it.

The main reason for not wanting to go there is that it has been known to cause serious overheating of some participants in this forum.

From Siemens[/URL]: "Note: A load neutral is not required on the circuit. However, the white line neutral (pigtail) must be connected to the panel neutral for the device to function."

Should say test device I would think unless they have something in there that won't allow the thing to function unless it senses 120 between 1 or both phases and the neutral and I can't think what advantage there would be to that. More modern GFCI's now launch a 120Hz test signal and expect it to be completely returned through the load terminals. This is, I think, to detect faults between like phases of separate circuits. Maybe it has something to do with that.

 

[ajdelange]

Those HHN circuits were only allowed when wired directly to the main service panel. That's why mobile homes have always used 4-wire outlets for dryers; their main service disconnect is out on the pole. So the 3rd wire is connected to BOTH the ground bar and the neutral bar because they are both tied together in the breaker box. (this assumes it was installed correctly)

The neutral and ground should only be bonded at the 'service entrance' and no where else. If the service entrance is on a pole then that is the only place neutral and ground should be bonded. Both must be run from the service entrance to any panel but they must be kept separate there and the panel must be bonded to the ground - not the neutral. Even electricians don't understand this. When my garage/brewery was built the service entrance for the house was moved to a box on the outside of the house and three panels in the house and garage fed through breakers from there. The electrician bonded neutral to panel and took that bond as the source of ground within the garage. The inspector said 'No, no' and made him tear out dry wall to run the proper ground conductors (from the rods at the service entrance) and separate them at the panel. This is why I am sensitive to this issue.

You can safely use it for a neutral connection OR a ground -- but you shouldn't use it for both (actual electric dryers exempted.)

Don't follow this. There must be a separate grounding system conductor and neutral. They can, and must be, joined only at the service entrance or at the source of a separately derived system (coming up).

Another way to derive a small 120V from a pure 240V for a light or timer or something is with a transformer.

This is the only legit way that I know of (other than an M/G set) to derive 4 wires from HHG. Were OP to use a transformer for 120 he would have to join one side of the transformer (or the center tap if he got a 120/0/120 transformer) to the main source G wire which would still be bonded to the box. He can then, because this is a separately derived system, tie the neutral of this separate system to that bond.

I have no idea what a little 1 to 2 amp transformer would cost, (and an inline fuse) but probably not much.

You'd be surprised (and not pleasantly). But all of this is moot as the Brew Boss has solved this problem by getting 120 (and its neutral) from a separate circuit.

 

[z-bob]

Originally Posted by z-bob View Post
Those HHN circuits were only allowed when wired directly to the main service panel. That's why mobile homes have always used 4-wire outlets for dryers; their main service disconnect is out on the pole. So the 3rd wire is connected to BOTH the ground bar and the neutral bar because they are both tied together in the breaker box. (this assumes it was installed correctly)

The neutral and ground should only be bonded at the 'service entrance' and no where else. If the service entrance is on a pole then that is the only place neutral and ground should be bonded. Both must be run from the service entrance to any panel but they must be kept separate there and the panel must be bonded to the ground - not the neutral.

We're saying the same thing. If you have a properly-installed HHN dryer or range receptacle, it must originate in the service entrance panel, the single point where the ground and the neutral are connected. That's why you've never been able to have a 3-wire dryer cord in a mobile home; they are bonded at the meter instead of the breaker box, and there are 4 wires coming in.

I'm not an electrician, so I might be using the terminology a little wrong. I purposely did not say "service entrance panel" in my post because I didn't think anyone except the electricians would know the significance of that word. (don't get be started about grounded vs grounding conductors)

 

[ajdelange]

We're saying the same thing.

I think the intent is the same.

If you have a properly-installed HHN dryer or range receptacle, it must originate in the service entrance panel, the single point where the ground and the neutral are connected.

If the grounded conductor is uninsulated the cable must be type SE and must connect at the service entrance. Otherwise there is no restriction as to where the circuit can be sourced. But this is for existing wiring only. All current wiring must be done with G and N present.

That's why you've never been able to have a 3-wire dryer cord in a mobile home; they are bonded at the meter instead of the breaker box, and there are 4 wires coming in.

There is a separate paragraph (550.16) that says that no appliance frame may be connected to the grounded conductor (neutral). IOW the exception that used to apply in homes never applied in mobile homes/RV's/campers...

 

[Twang]

If you want to use a sub panel for just the 240 then essentially yes. Do not connect the GFCI white wire and connect the green or bare wire from the feed to the ground bus at the right of the box. Do not run a neutral wire to the load. The ground (bare) wire should be connected only to the ground bar on the right side of the box in the picture and that bar should be bonded to the box.

Just to double check, this is how I should wire the spa panel? No neutral in or out. Do not connect curly GFCI neutral wire to bar (put a wire nut on it?). And the GFCI will still work for safety purposes? (Excuse the Paint hack-job)

Keeping in mind there is a separate 120 feeding the brew boss controller for pump and lights/etc.

 

[z-bob]

I would be tempted to put the white pigtail lead on the ground bar. I would at least try it; it will either give you a working TEST button, or cause the GFCI to trip immediately. (I'm betting on the TEST button)

 

[ajdelange]

Just to double check, this is how I should wire the spa panel? No neutral in or out. Do not connect curly GFCI neutral wire to bar (put a wire nut on it?). And the GFCI will still work for safety purposes? (Excuse the Paint hack-job)

Yes, that should be fine if the breaker is the conventional sort of GFCI breaker and if the test circuit is between the two hots. If it isn't, (i.e. between one H and neutral) then the test button won't work. In this case connect the white wire to the ground bar (at the right) and try it again. This should make it work. You will only be connecting supply conductors to ground when you make the test (for a few milliseconds) so while this may be a letter of the code violation it certainly isn't one in spirit.

 

[JONNYROTTEN]

I called Eaton the manufacturer of my box to get a definitive answer,This is what I was told by the tech dept.

The GFCI portion of the breaker runs off of 120v (The neutral)If you do not have 120 coming into the box the GFCI WILL NOT WORK. He said "if" the neutral is tied in with the ground in the breaker panel that would give you 120. you can then disconnect the white neutral prewired to the neutral bar and connect it to the ground bar. And it "may" work.Test by pushing test button.THEY DO NOT RECOMMEND THIS METHOD.

edit-IF THE GROUND IS JUST A GROUND= NO GFCI

 

[ajdelange]

This is what I was told by the tech dept.

The GFCI portion of the breaker runs off of 120v (The neutral)If you do not have 120 coming into the box the GFCI WILL NOT WORK.

What this means is that the faults are sensed electronically and that the breaker is launching the 120 Hz signal I referred to in an earlier post. The chip (LM1851 or something similar) is powered by a bridge rectifier (whose pulses also supply the 120 Hz signal) and that DC is also used to trip the breaker (by triggering an SCR when the chip detects imbalance). Connecting the N wire to earth will provide the necessary source for the electronics but it does violate code as the current necessary to operate the circuitry, though small, would be drawn through the ground wire which is not supposed to be used for that role.

He said "if" the neutral is tied in with the ground in the breaker panel that would give you 120. you can then disconnect the white neutral prewired to the neutral bar and connect it to the ground bar. And it "may" work.Test by pushing test button.THEY DO NOT RECOMMEND THIS METHOD

I wouldn't recommend it either.

edit-IF THE GROUND IS JUST A GROUND= NO GFCI

It should work as the ground and neutral are tied together in the main panel. Thus there is 120 between the ground and either of the hots. Still doesn't mean I'd recommend it.

OP's recourse here is to try to get an old style (passive) breaker. I have no idea whether they are still made as the new ones will detect a neutral to ground fault when no load is energized and that may be a new requirement. Or he can install the breaker in the main panel where the neutral bar is available (he just wouldn't connect anything to the breaker neutral terminal). Or, and this one is a bit of a stretch, he can derive neutral at the sub panel by means of a small (only needs to be big enough to run the breaker electronics) transformer. I'd be comfortable doing that but it may be beyond his comfort zone.

 

[Fontlaroy]

# 10 wire is not rated for 50 amp breaker. You should buy a new 30 amp gfi and install in main panel. Ground and neutral should only bonded together at first point of disconnect

 

[Fatman_Brew]

# 10 wire is not rated for 50 amp breaker. You should buy a new 30 amp gfi and install in main panel. Ground and neutral should only bonded together at first point of disconnect

The OP is using a circuit with 30 amp overprotection at the main panel. The 50 amp GFCI is just providing ground fault protection, no current overprotection.

 

[Fontlaroy]

I should have read the whole thread. Most importantly make sure you have good ground.