magnj
Well-Known Member
Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.
Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.
Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.
EDIT: Sorry...since the 120VAC is coming from another source how is the breaker going to be powered since it snaps into the same bus as the 240VAC 2-pole breaker...? If you use this method then the 120VAC breaker is powered off one of the legs of the 240. Deaf, where id your 15A GFCI...in your main panel feeding the rig?
Ok, any particular reason? I thought it was more of a plug in type thing?
Any suggestions on spa panels?
I guess I could build 2 separate boxes...But this is getting more complicated and more hacky than I had hoped
Ed,...
I have no idea how far this outlet is from the main panel on the property, but I think P-J was about to suggest running a separate ground for the outlet and using the current ground wire as a neutral wire. I think that would be a great option if the conditions are right.
Dig a little deeper into the code. There are exceptions. Try NEC 250.130 (C) for a start.... All conductors (including ground) must be in the same cable or conduit (NEC 250.32 (B), 300.3 (B)). ...
I believe DeafSmith has said it but just to clarify a 240VAC GFCI does NOT need a neutral. It actually "watches" the current on both hots and trips when there is a difference. Which is different from a 120VAC GFCI which "watches" the hot and neutral.
I disagree with this. The GFCI breaker I just wired in 2 weeks ago I messed up on. I ran both hots from the outlet to the appropriate screws on the breaker. Not thinking about it being GFCI, I ran the neutral wire from the outlet to the neutral bus instead of to the GFCI breaker. Anytime I put any load on the circuit, the GFCI would trip. The whole reason GFCI breakers have the pigtail is to complete the neutral path after wiring the outlet to the neutral screw on the GFCI breaker. This experience would contradict your statement that it merely watches both hots. This was a GFCI from the HD Spa Panel. There are 3 screw positions on the GFCI breaker, 2 for hots and one for neutral.
I can't stay away from this thread. The link posted very early (how GFCI works) has all the goods in it.
I'd like to try and summarize the clever science involved in a way that is not terribly difficult to follow, because when I read about it to gain my own understanding I found it very elegant and simple. Pure genius, really.
The key to the whole thing is a small coiling piece of metal, formed into a ring like a donut. If you take a device like this and run a wire through the center of the donut, you have the beginnings of a GFCI device. When current travels along that line through the hole, electro-magnetic forces are created around the wire. These forces cause current to start to flow through that coil, even though the donut and the current carrying wire are not actually physically in contact with each other.
When current is flowing one way (say left-to-right) in the wire, the current in the coil flows one way (say counterclockwise around the donut). When current on the wire in the hole moves the other way (right-to-left) the donut carries current in the clockwise direction.
When there is no net current moving on the line int he center of the donut, the donut coil itself carries no current.
So.... to make a GFCI detector....
All lines that are permitted to carry current in the circuit (be they hot lines or neutral lines) are passed through the doughnut hole together. The coil will monitor ALL of them simultaneously. If there is a net current flowing left-to-right, the coil carries counter-clockwise current. If there is a net flow of current from right-to-left, the coil carries clockwise current. If there is no net flow of current, the coil carries no current.
All that needs to be done then is to have circuitry that monitors the current IN THE DONUT COIL itself. If there is ever current moving around the donut in either the clockwise or counterclockwise direction at all, then that means that net current of the total group of lines passing through the center of the donut is not balanced and some current has found an alternate way of getting out of the system.
It does not matter if you are monitoring 1 hot and 1 neutral, 2 hots alone, 2 hots and a neutral, or even 101 hots and 37 neutrals.... it is totally irrelevant. All that matters is that all of these lines are passing through the hole of the magic donut coil and that the amount of current that is flowing left-to-right in some of the wires in the group is also flowing right-to-left in other wires in that group.
A GFCI breaker works by monitoring the difference in current between hot and neutral, regardless if it's 240v or 120v.
http://www.ehow.com/how-does_4898026_gfci-circuit-breaker-work.html
That is how it works. GFCI breakers have pigtails for a reason. They will not work without connecting the neutral from the receptacle to the breaker.
GFCI CORDS are different. I have no say on that. But GFCI BREAKERS must have the neutral connect to work. I was merely disputing the statement that he said it monitors both hots to check for current differences.
Ah after reading that thread, I see where you wouldn't need a neutral. They make 2 pole GFCI breakers that don't have a neutral input and they just monitor the hots. But with this type, you can't break off into a separate 120v leg inside your control panel. I stand corrected somewhat, but for the breaker in the HD spa panel, you still must have the neutral for it to work.
How do I know if the third wire is being used as neutral or ground?
Thanks for all the help guys. However because of my lack of electrical knowledge and the costs, I think I'm going to end up going with a 120V setup to just maintain mash temps and use propane to do major heating and boiling.
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