Can't get my 220V tools to work.

[Rob Price]

We just moved to a new house, and I've spend the past couple of days off wiring everything up. I've gotten all my standard 20A 115V outlets working, I went to install my 220V lines today and the tools won't turn on.

I installed a slim line 20A double pole breaker (trying to save room, but my first trouble shooting step will be to replace this with a standard double pole) in the box. Connected the white and black wires to the breaker, ground to the ground bar and ran the wire inside. From there it goes to a 20A double pole switch so I can turn everything off and on from inside the shop. I confirmed when the switch is off there's no power to either tool. When it's on I get power to both the white and black lines. These are wired to 20A receptacles. I confirmed power is getting to both the black and white lines of my tools, but neither of them will switch on.

Thoughts?

[Mark Bolton]

My thoughts are I have no idea why in the world you'd wire through a switch.

[Jamie Buxton]

You might be feeding both hots from the same phase. Each hot will measure 110 volts to ground, but there will be 0 volts between them. If you move one hot to the other phase, you get 220 volts between them.

[Jim Neeley]

Rob,
A single unit consisting of two half-width breakers cannot provide 240V because they pull both legs from the same pole. If you take a voltmeter and measure across them, you will measure zero volts.

If you want to go with half width breakers to save space, you need to get a unit the size of a conventional 240V breaker (two 120V breakers wide) that has four half-width breakers within it and the center two tied together so they trip at the same time. In that case the center two provide 240V and the outer two provice two separate 120V circuits.

There are a few companies (Siemens is one, I have one) who make these with the two inner breakers tied together and the two outer breakers together, which gives you two 240V circuits from the space of one 240V traditional breaker. The others use the inner two as a 240V and the outer two as separate 120V circuits.

Jim

[Rob Price]

Switch: because my buddy had his shop burn down one night because one if his tools shorted in the night. With the switch, all my outlets are dead. Nothing gets left on by accident and nothing can short out while I'm not there. Not to mention it's one more step to prevent little hands from starting tools.

It was the tandem slimline. I went out and tried two regular sized 20a breakers and all is well. I'll get a true double pole tomorrow. Didn't realize the tandem was still only single phase. Not sure what I'd use on for. I'm assuming it will run two 115 20a circuits just fine?

[Ryan Mooney]

Not sure what I'd use on for. I'm assuming it will run two 115 20a circuits just fine?

I wouldn't recommend using it for that, it is actually a 220v breaker. There are some panels that support half height breakers in some of the slots. Its possible/likely your backplane supported it (otherwise I'm surprised it plugged in.. some won't let you although I can't say that's universal) and you had it plugged into the wrong position (it has to span legs just the same and the manual for your panel should diagram or explain where they need to go). You should be able to find the manual for your panel with a quick google search on the part # unless its something really obscure.

[Bill McNiel]

I have a masters degree and still have no idea how electricity works. Worse than that, I wired my house and shop!

[Kevin Goss]

Yeah, a tandem is designed simply for if you run out of spaces in your panel, you pull a current single pole breaker and replace it with a tandem. So you definitely can run 2 120v circuits off that breaker. That's the right way to do it, while others just simply put 2 wires under one 20 amp breaker since tandem breakers are not very cheap.

[Mark Wooden]

I have a masters degree and still have no idea how electricity works. Worse than that, I wired my house and shop!

Try wrapping your head around this- in my new shop space,the existing service is a "240/480v three phase, Delta service with owner supplied neutral. I'm supposed to be able to run my three phase equipment on two legs if I supply the neutral. I'm not even going to pretend to understand how it works and am trying to get the landlord to put in a new 208-230/460v three phase service

[Tom M King]

Take four of the single space breakers out of the box. Hopefully, you can find four that are side by side the same amperage. For the two farthest away from the way the wire comes into the box, put a double pole breaker there for your 220 circuit. In the other two now empty slots, put two of the space saver breakers, like you are trying to use to get 220 (which won't work), and put the four wires( from the four breakers referred to in the first sentence of this post) on those breakers.

If this doesn't make sense to you, call an electrician.

[Wade Lippman]

I have a masters degree and still have no idea how electricity works. Worse than that, I wired my house and shop!

I presume you mean you don't understand Maxwell's equations, rather than you don't understand the principles of residential wiring.

[Mark Bolton]

Switch: because my buddy had his shop burn down one night because one if his tools shorted in the night. With the switch, all my outlets are dead. Nothing gets left on by accident and nothing can short out while I'm not there. Not to mention it's one more step to prevent little hands from starting tools.

It was the tandem slimline. I went out and tried two regular sized 20a breakers and all is well. I'll get a true double pole tomorrow. Didn't realize the tandem was still only single phase. Not sure what I'd use on for. I'm assuming it will run two 115 20a circuits just fine?

I would be more apt to blame your buddies doing his own wiring or some other event as opposed to the circuits being energized when he wasn't there. Tools, or proper wiring, don't burn shops down.

If there's something in the circuit that's going to catch fire if left on you've got far greater problems than any switch will protect you from.

[Rod Sheridan]

It was the tandem slimline. I went out and tried two regular sized 20a breakers and all is well. I'll get a true double pole tomorrow. Didn't realize the tandem was still only single phase. Not sure what I'd use on for. I'm assuming it will run two 115 20a circuits just fine?

Regardless of whether you use a single pole, or two pole breaker, it's all single phase.

That's all you have at home.

The issue was that the tandem breaker is two breakers connected to the same pole, so you had 120 volts to neutral, zero volts line to line............Rod.

[Myk Rian]

I have a masters degree and still have no idea how electricity works. Worse than that, I wired my house and shop!

Lol. Good luck.

[Jason Beam]

I think the OP needs to call an electrician. There are too many signs of unfamiliarity with the way residential wiring works to trust that advice given over the internet would be safe.