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rjbrown 04-04-2009 07:11 PM

Wiring Help!! ASAP PLEASE
Ok guys I got a compressor and I need some help wiring it up. For the time being I am making a homemade extension cord and running it into my dryer plug in. Reason being I live in an Apartment. I have a total of about 35 feet of 10-3 wire. It is 3 wires total. Black, White, and Green.

Here is what I have. The wires shown in the pictures are already wired to the compressor.

And here is my dryer plug in and I wired it like shown. This is how the instructions told me that came with the plug.

Which wire goes where?

ANY help will be GREATLY appreciated!!!!

Oldguy48 04-04-2009 07:37 PM

Looks like your compressor requires 220 V to operate. Check your dryer receptacle with a voltmeter. You should find that you have 220 V on the two flat openings that are parallel to each other. The round terminal should be the ground, and if you measure voltage between the round opening,and the "L" shaped opening (the neutral), you should have nearly zero volts, since electrically, they are the same connection back in your breaker panel. Measured voltage between the round opening and either flat openings should be about 110 V. If your compressor requires only 220 V, you won't need any connection to the "L" shaped terminal. This is all assuming that your dryer receptacle is wired correctly. The voltmeter test will ensure that you are making the proper connections. Please realize that you are dealing with potentially lethal voltages. Be careful !!

rjbrown 04-04-2009 08:48 PM

Well my dryer runs off it just fine so I am assuming it should be exact.

My compressor is 220v.

So which colored wires go where on the compressor box? and which color is which? is black hot? or ground? etc etc

fast68 04-04-2009 09:39 PM

you need two incoming hots to run 220

two wires from the circuit panel with their own breaker each

white is neutral

and green is ground

of course

so you need 4 wires total in the incoming cable from the circuit panel

two blacks
one neutral
and one ground

220 is just two 120 breakers from in the circuit panel both with their own breaker

we are using larger than 10 guage for our air compressor but it is a big one

also bigger than 10 guage for the twin post vehicle lift motor as well

we dont have a ground cable for ours

just the two hots and the neutral

rjbrown 04-04-2009 10:29 PM

So is this the wrong wire?? Its a 220v compressor. Can I use this line or no?

My compressor is a 60 gallon, 5 hp, 23 amp compressor.

scr8pin_f100 04-04-2009 10:38 PM

Hey, another thing to make sure you check out is the recommended breaker size for your new compressor...I say that because I have a friend who did exactly what you are trying and his breaker for the dryer plug kept blowing..He ended up having to bite the bullet and get another breaker installed into his box and ran the compressor and his welder off of it..I understand that with you being in an apartment you might not be able to do this..But, if you get the wiring figured out and it starts blowing breakers, you'll know why..GOOD LUCK!

cobalt327 04-04-2009 10:42 PM

There are some VERY savvy folks here on this forum, no doubt about it.

But it is like going to a proctologist for a runny nose, when you go to a hot rod forum and ask about 220VAC wiring, IMO.

Check this site for wiring 220VAC with 3 or 4 wires:

rjbrown 04-04-2009 10:44 PM

Im running it into a 30amp breaker. The compressor says its 23amps. Is a 30 amp breaker enough?

chewyscool 04-04-2009 10:58 PM

30 amps is enough 30 x .80 = 24 allowed.

crownver 04-04-2009 11:22 PM

Looking at the wiring diagram for the compressor, you wouldn't use a neutral. Normally with a unit like this, you would have a red, black, and a ground. Both red and black are 115V, and in this situation a neutral is not needed. Your dryer may be set up differently.

Franzę 04-05-2009 12:51 AM

For the love of doG, lets everybody who doesn't know the answer to the question just tuck your code books back into your pockets and quit posting.

The answer to eht question is simple.

Remove the white wire from the L shaped male plug and move it to the contact opposite the black wire.
The black wire is at the 3 oclock position, and the white wire should be at the 9 oclock position.
If you suffer from a need to be socially compliant to rules that hold no meaning put a stripe of red nailpolish on the white wire at both ends of the cord.

Happy compressing

speede5 04-05-2009 12:55 AM

Is it common in the U.S. to refer to the ground/green/bare as a wire? When you say three wire to me I am assuming you mean Black/Red/White. The bare or green doesn't actually count as a wire and is not part of the descriptor. 10/3 should have two conductors, a neutral and a ground wire.

Franzę 04-05-2009 01:16 AM


Originally Posted by speede5
Is it common in the U.S. to refer to the ground/green/bare as a wire? When you say three wire to me I am assuming you mean Black/Red/White. The bare or green doesn't actually count as a wire and is not part of the descriptor. 10/3 should have two conductors, a neutral and a ground wire.

There is no commonality in the US when it comes to electrical descriptors. We lack the commonality Canada has because we also lack any formal licensing system going beyond State level, so you can drive 50 miles between jobs and have no idea what a wireman is saying.

In terms of wire description, since 1964 all building wire such as Romes and Subfeed are called out as 2 wire or 3 wire which means 2 or 3 conductors + mechanicle ground. The bare or green wire is the mechanicle ground and is not considered a current carrying conductor. The actual marking on the jacket will say 10/2 WG indicating normally 2 current carrying wires and the mechanicle ground. Of course none of this applies to preassembled bundle wiring or EZ pull precut assemblys.

None of this applies to our only National system Mine Safety & Health Administration, since they don't adhere to the National Electrical Code which is written by a provate agency and only mandated if the local AHJ adopts it.

Neutral is considered a conductor although it only carrys current in 120 volt situations and imbalance current in 240 volt situations.

Due to a complete lack of licensing meaning anything, and inspection being a joke for the most part, NEVER count on wire colors (colours for Canadians) meaning anything in US wiring. Phase rotation is something US wiremen might begin to understand in the next 50 years.

speede5 04-05-2009 08:43 AM

I take it your a cynic? lol. Sounds like we are more regulated in my province. I am rewiring my third home and we have a very well written code to follow. Electrical is regulated y the provinces, but most have adopted the same code.

Inspection is not a joke but it is far from ideal. For a homeowner it is usually done over the phone with the inspector, if you know what you are talking about you will never see him. Problem is probably similar to your area, one inspector for a huge area. Between my homes and my brother in laws I have seen many breaches, a wonder more houses don't burn down!

They recently stopped issuing homeowners permits in Saskatchewan. Now you can only get one if you have a close relative who is a journeyman, or if you live on a farm.

Franzę 04-05-2009 11:32 AM

Cynic, no, just someone who can see and read.

How about 8 story office buildings wired with Romex and subfeed cable?

We currently have 4 different inspection services authorized by the AHJ in my town, competing for the jobs. Most of the inspectors are clueless beyond single family residential.

Minimally 90% of the standby generators in the US are Natural Gas fired, and inspectors have signed off on them. Oddly the Code says emergency generators cannot be NG fueled since NG depends on electricity to pump the NG. When that is brought up the inspection service either doesn't know that section of code, or claims they don't enforce it.

Meanwhile half of this country is paranoid about pulling permits because they could loose their homeowner insurance and the other half is wiring up an electric stove with doorbell wire from Homo Desperate.

I'm old and I laugh a lot!

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