I need (in emergency only) to run my deep well pump off a generator, its 220V. I want to cut into tha wire that's in the basement going down the wall. There's a switch there to turn if off in emergency. I want to put a recessed male plug outlet next to that, which my generator will plug into.
The question is, what's the switch I should use? Don't really want to buy a $200 transfer switch. Just a LINE-OFF-GENERATOR 3-position switch, so that I can't feed back into the mains supply system.
While the one post here says -singlepole double throw- I tend to think in as much you are using 220 v that you would need a double pole double throw center off. Jack
If I were doing that I'd just install a female socket wired to the 220V feed from the existing switch and put a flexible cord with a matching male plug on the line going down to the pump. With the two plugged together you'll be back where you were, and if the power goes out you just yank the plug out of the socket and plug it into the genny, using a suitable extension cord if needed.
I wcan't comment on the codeworthyness of that kind of setup, but it will acomplish the job electrically without your needing to buy a new switch.
Considering that the local inspectors passed the central vac installation in our home when it was built, and the vac unit is permenantly mounted to a wall but is powered by a flexible cord plugged into an adjacent wall receptical, I'd guess it's not toooo bad a way to do it, huh?
No. DOUBLE pole, triple throw: Opens both hot wires, has three positions: Gen, center OFF, and Grid. The 3-way guarantees that there will never be a "make before break" situation, thereby energizing the grid (backfeeding).
Pop
: > The question is, what's the switch I should use? Don't really want to : > buy a $200 transfer switch. Just a LINE-OFF-GENERATOR
3-position : > switch, so that I can't feed back into the mains supply system. : >
Jeff I never thought of that. Are 220V plugs and sockets the same as the 110V ones?
Thanks all. I'm not sure what the number of throws or poles is, but I assume they say this on the switch? Could I also ask - do these look like regular wall switches?
center off toggle switches look like standard switches, but cost a lot. For a double pole your probably looking at $30. I like Jeff's idea, and it's a lot cheaper
What kind of connector do you recommend? The generator will have a typical 220V cable, I assume it should me just the same as that (male version) and that this should be close to the existing emergency switch (not sure which side though)
IMO Dean is asking questions which indicate considerable lack of electrical knowledge. Recommend get someone knowledgeable to help; otherwise something dangerous could occur? Such as feeding generator AC back into the hydro lines; with him being responsible for an electrocution?
There are many configurations of NEMA plugs. FWIW we use three pin plugs which have a 'conventional' looking ground pin but with horizontally polarized pins, for 230 volt. Can't recall if they are 15 or 20 amp capacity. Normal 115 volt plugs have vertically polarized pins.
But we also have some older three pin plugs for a couple of 230 volt applications which have a 'flat' third or ground pin and 'slanted' live pins. Perhaps somewhat similar IIRC to Australian 230 plugs?
Poster needs to know how to wire these correctly and safely! It's worrying!
PS. I finally came across a double pole switch to install on our 230 volt bench saw. Until I get round to doing that will continue to unplug completely between cuts, for safety. While blade is lowered below the table when saw not in use, also thinking about adding an extra 'safety' interlock device to prevent an occasional user or child from switching on the saw in my absence. Possibly something that goes on my keychain? Any ideas? Maybe a small permanently short-circuited two pin plug to push into a socket wired in series with one leg of the 230?
In switch language, the number of "throws" indicates the number of "destinations" for the power to go. A "center off" position for the switch does not send the power anywhere (or from the point of view of the person installing it, there are no terminals associated with the center off position). There are only two throws.
This is the key to what is needed. We have a Square D transfer panel that feeds certain branch circuits from either the utility power or a generator. It uses common power busses with eight breaker positions. The two sources are connected through back fed breakers that have a mechanical interlock that not only allows only one to be on at a time, but forces the one that is on to be shut off before the other can be turned on. The inspector took the time to ensure that a make-before-break operation existed, for both going from utility to generator, and the other way around.
Throw indicates whether the switch makes contact in the direction it is thrown. Single throw indicates that the switch has two contacts that make in one position. Double throw indicates that the switch closes different contacts in each position.
Poles represent the number of contacts that operate simultaneously. In the US, 120 volt switches are typically single pole with the neutral side connected unswitched to the load. 240 volt circuits use double pole switches to open or close both sides simultaneously.
120 volt on-off switches are typically SPST (single pole single throw), and 240 volt switches ate DPST (double pole single throw). A 120 volt
3-way switch is SPDT (single pole double throw).
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