Adding 220 20A breaker but it trips when turned on

mi_fiveo

I'm trying to add a 220 circuit from my 200a panel in the basement to my garage to power an air compressor. The compressor calls for 15a 220V so I purchased a 20A double breaker, 25' of 12/2 romex, and a disconnect box to mount in the garage. I planned on connecting the compressor directly to the disconnect box to avoid having to buy a plug and receptacle. From what I have read, 12/2 romex will work fine since it is only a 20a breaker.

I hooked up the disconnect box in the garage with white and black to their own post and ground wire to the ground wire lug. The compressor would go to the other two posts with the ground wire to the ground lug. I did not hook it up yet though. I hooked up the 20a double breaker with black wire to one post and white wire to the other. I ran the ground wire to the neutral bar and then snapped it into place.

Before connecting the compressor to the disconnect box I attempted to flip the breaker expecting it to power on. It blew instantly and I flipped it back to off. What did I do wrong? I assume it is something to do with the disconnect box that I used. Does it matter that the compressor is not wired in to it yet? I think the box is rated for 60A and is non fused. There is a simple blade that you pull out to kill power at that box.

Ok thats my best explanation, I need some expert help. Thank you.

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Speedy Petey

You created a DEAD short.
Look at the terminals on the disconnect. Next to them are the words LINE and LOAD. You connected to line and load with your feed. With the pull out in place it is a dead short.
The feeds go on the LINE terminals.

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mi_fiveo

i'll go look if it is labeled. so one wire goes on each side?

k_buz

If the compressor is calling for 15A 240V circuit why in the world would you install a 20A breaker?

mi_fiveo

Yes, I see where they are labeled now. Looks one wire goes to each side. Thats what I get for assuming they go together on one side. Thank you.

I put a 20A breaker because thats what was recommended by others who told me the compressor might trip the 15a breaker on startup.

Jim Port

You did not strip enough sheath off the cable in the panel. You should have at least 6" of free conductor.

The white should also be marked as a hot with tape or a magic marker. Black or red would work.

The cable also needs to be secured within 12" of the disconnect.

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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.

k_buz

What do the specs say? If the compressor is calling for a 15A 240V circuit, you need to put it on a 15A 240V circuit.

If the specs are saying that it runs at 15A @ 240V then a 20A circuit is probably good.

mi_fiveo

Jim Ill fix that thanks.

K_buzz, I'm not sure its a 60 gallon compressor it just says 15A at 220V

k_buz

Make and model number?

Where does it say this? In the instructions or on the compressor itself?

mi_fiveo

ch model vt558705aj
60 gALLON 5HP pump
Says 230 volts 15 amps

k_buz

Nevermind....

k_buz

I do not believe a 20A circuit will be large enough for a 5 HP motor. I am going to do a little more research, but I am having a hard time finding the specs for this unit.

Does it have a spec plate?

Can you list all the specs? Specifically if it has something labeled FLA...

kevinp22

spec plate - hard to read says 230v 15.0 amps

kevinp22

easier to read plate

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k_buz

Looks like you will be OK with that 20A circuit.