What kinda plug is this?

[CPeter James]

Just a suggestion. If the all 240V (nominal) circuits are wired using 12-2 wire I would wire all of them with L6-20 outlets and put L6-20 plugs on the cords and then build an extension cord with L6-20 fixtures. This gives you great flexibility and for that time when you need to move a tool to mill a very long board, you have the extension cord to allow it. Also, it you decide to rearrange your shop, you can do that.
CPeter

[Jim Riseborough]

I have all my tools and a cord with L6-20 already. I will switch the wall outlet to match.

[John K Jordan]

For some who have responded, please ask yourself why it's called "240V" if you don't measure 240V somewhere.

The actual voltage at any one outlet it may vary considerably over time, the exact voltage depending on factors such as the utility capacity, distance, wiring, and how many users are sucking how much power from the system at the time. I usually see between 220 and 245+. (At the moment, the UPS servicing my cable modem and router measures the line voltage at 123.) At times of peak use (hot summer evenings) power companies have been known to implement rolling brownouts (intentional voltage reduction) to prevent total blackouts.

I think it is tradition that allows 110/220, 115/230, or 120/240 to all be correct. The exact numbers used may matter to a purist, an "expert", or the electrical police. I think the important thing is that everyone understands that saying 220 or 230 or 240 means the same thing to normal humans.

JKJ

[Jim Becker]

"Today's" nominal supply voltage to homes, etc., is 240v, but John is correct that it absolutely varies for many reasons and the "nominal" has changed over time. I actually had an issue here a number of years ago where the line voltage was dropping far enough that my MiniMax slider was shutting down. (the electronics monitors voltage and when it drops below a minimum level, it cuts off the machine from starting) The power company wouldn't do anything about it, so I had to install a transformer on the machine to rectify things. Two years later, they actually did change out an old transformer at the pole and the line voltage magically returned to "normal".

[Dan Friedrichs]

I think Malcom's point is that if you measure "0V", it's not 220/230/240V

[mike wacker]

Mr. Becker is correct. The 2 hot legs of typical USA household 240VAC service are each at 120VAC potential (to ground), but their wave forms are 180 degrees out of phase (offset from each other), so the simplistic result is that at any particular moment you measure from the 'peak' of one to the 'valley' of the other - - and get 240V. This 240V is what a meter should 'see', as well as your 240V motor, etc.

If you measure 120V on L1<>G and L2<>G, but get (zero) 0V from L1<>L2, then the receptacle is incorrectly wired for use with anything. The only way anything will function on this is if it uses the Gnd lead as a conductor. Generally speaking, this would also imply there is a problem with the wiring in the 'motor' allowing current to flow to the ground, but this opens a whole new rabbit hole of speculation and conjecture.

Photos of meter on a 240V AC circuit, and what it should read on a properly wired 240VAC plug, like the OP's follow:

This from left leg to ground--
Attachment 353811

This from right leg to ground--
Attachment 353812

This from left to right leg--
Attachment 353813

For some who have responded, please ask yourself why it's called "240V" if you don't measure 240V somewhere.

Malcolm,

Very fine post with GREAT pictures. Nice Job. Really boils the point down to what the receptical (sp) should be delivering if wired correctly.

[mike wacker]

The actual voltage at any one outlet it may vary considerably over time, the exact voltage depending on factors such as the utility capacity, distance, wiring, and how many users are sucking how much power from the system at the time. I usually see between 220 and 245+. (At the moment, the UPS servicing my cable modem and router measures the line voltage at 123.) At times of peak use (hot summer evenings) power companies have been known to implement rolling brownouts (intentional voltage reduction) to prevent total blackouts.

I think it is tradition that allows 110/220, 115/230, or 120/240 to all be correct. The exact numbers used may matter to a purist, an "expert", or the electrical police. I think the important thing is that everyone understands that saying 220 or 230 or 240 means the same thing to normal humans.

JKJ

Let me throw another wrinkle in the whole 110/220, 115/230, 120/240 volt numbers. If you're really close to the Utility's sub station you might even see 125/250. Not a big deal except for your old incandescent lamps that would be brighter but not last as long, lol. And to throw a real twist in, if you where in a heavy urban area, think big city, New York, Philly, Chicago, etc, you might be on what I've heard called 3-wire network. That would be two legs of 208 volt three phase so now you might be measuring 120/208. No worries, all your tools, electric stoves, dryer are all designed to go roundy round with these ranges of energy delivery. Being a nerd sucks sometimes.

[Eric Anderson]

I'm not an electrician, and there are many more folks more knowledgeable about electricity than me, but I thought when doing 240v wiring, where there was not both 240 and 120 together, (like a dryer or range) that you wire the two hots and the ground and not the neutral. In the picture above, it appears that the neutral is wired to the receptacle and I was thinking the ground should be wired and the neutral capped off. Is this wiring correct?

[Malcolm McLeod]

I'm not an electrician, and there are many more folks more knowledgeable about electricity than me, but I thought when doing 240v wiring, where there was not both 240 and 120 together, (like a dryer or range) that you wire the two hots and the ground and not the neutral. In the picture above, it appears that the neutral is wired to the receptacle and I was thinking the ground should be wired and the neutral capped off. Is this wiring correct?

Assuming the overall physical condition of the wire itself is sound (no broken conductors), then the bare ground wire should terminate on the back of the receptacle. The white (neutral) should be wire nutted (or at least taped). - - And I believe Jim R. has stated he intends to re-wire to conform to this.

It may have been wired as he shows in the pictures for any number of reasons: the ground is damaged/broken (and 'white' is OK); the original installer/previous owner didn't know any better; or, the ground wasn't landed in the panel; etc..

[Jim Riseborough]

Assuming the overall physical condition of the wire itself is sound (no broken conductors), then the bare ground wire should terminate on the back of the receptacle. The white (neutral) should be wire nutted (or at least taped). - - And I believe Jim R. has stated he intends to re-wire to conform to this.

It may have been wired as he shows in the pictures for any number of reasons: the ground is damaged/broken (and 'white' is OK); the original installer/previous owner didn't know any better; or, the ground wasn't landed in the panel; etc..

Im not sure. The new plug I bought shows being wired with 2 hots and a ground

I get 120 if red/black to ground, or to white. It seems both are ok, just the white is acting the ground, since I dont need a neutral really?

IMG_2564.jpgIMG_2565.jpg

[Malcolm McLeod]

Jim, I was trying to answer Eric's question and may have gone too far.... Eric was correct that the bare ground wire should properly swap positions with the white neutral, based on your original photos. You plan to do so was also correct. Sorry if I've muddied the water.

On your new receptacle, it gets wired the same way - red and black to the 2 hot lugs respectively, and bare copper ground to the green lug, white gets capped off.

Other's have done a better job that I can about why in other threads - - but bottom line is that the white wire and the ground both have the same voltage 'potential' (and could function one in place of the other, except this is against code).

White wires are there to carry current in normal situations; ground wires only carry current when something is wrong. If we all use the same standard, nobody gets a nasty surprise.