Adding compressor to 220v in my garage

[Scotty Dive]

I will be adding a 60 gallon 3HP single phase compressor to my garage and will be using the existing 220V outlet I had run (by an electrician) for me last year for a welder. The welder just plugs into the outlet when needed. I will be running a plug on the end of the compressor (will need about 25 feet of wiring) and will use the 220V that same way so the welder or the compressor will never be on at the same time.

When I started to think about this, I noticed the outlet receptacle says 125V 30 amps. This outlet was purchased to match the plug that the welder had from the factory. My question is - shouldn't that outlet be rated 250v and not 125? It has not given me any problems or have I noticed any heat from the outlet box.

I just want to make sure everything is correct before I buy a new plug and cable and start wiring it up like on the welder set up.

 

[BeezFun]

That's a 125v plug and receptacle, are you sure your welder is setup for 220v? Some welders will run either 110 or 220, there's switch to change it on the back or under a panel. Look at the breaker to verify whether it's 110 or 220. You can convert to 220 without much trouble, provided the wire size is adequate for both the welder and compressor.

 

[Scotty Dive]

BeezFun - you definetly have me scratching my head. What I do know is that the circuit is 220V and has a 50 amp breaker and there is 210V at the outlet box (I remember seeing the electrician test that). The welder is a longevity and looking at the manual - it says it is dual voltage - 110 ov 220v. Whats interesting, is that it was wired from the factory with the above pictured plug. I will call longevity and talk to someone live to get that portion of this resolved.

 

[arlen4720]

Some of the new inverter type welders don't care whether it's 220 or 110....kind of like switching power supplies on electronics. One thing is for sure though, that is not the correct plug for a 220 V application. It will handle 30 amps at 220... no problem, it is just not the "right way" to do it. continuos 50 amps would burn it up. I would replace the plug on the welder, change the receptacle, and get everything correct. Verify the wire size, and size the plug and breaker accordingly. Depending on if the air compressor has it's own motor short circuit protection, be mindful of having an oversized branch circuit overcurrent protection device....Your motor may not be protected properly.

 

[Scotty Dive]

Some of the new inverter type welders don't care whether it's 220 or 110....kind of like switching power supplies on electronics. One thing is for sure though, that is not the correct plug for a 220 V application. It will handle 30 amps at 220... no problem, it is just not the "right way" to do it. continuos 50 amps would burn it up. I would replace the plug on the welder, change the receptacle, and get everything correct. Verify the wire size, and size the plug and breaker accordingly.

I agree - two new plugs (one for welder and one for new compressor) and a new receptacle to match the amperage/wiring. Arlen - I am not sure I understand what you meant by this - Can you rexplain it for me?

Depending on if the air compressor has it's own motor short circuit protection, be mindful of having an oversized branch circuit overcurrent protection device....Your motor may not be protected properly.

 

[buickanddeere]

As previously stated. May as well wire the plugs and welder for 240V and a two pole breaker. There will be less light dimming when striking an arc.
3HP typically runs 17amp full load on 240V. Calls for 10awg wire. Thermal overloads set at 21.25amp. 50amp P fuses, 25amp time delay fuses or a 40amp breaker for short circuit protection.
I would run a 2nd circuit instead of plugging and unplugging.
A set of 20amp T-slot split receptacles on their own pair of 20amp breakers. Less flicker when starting a plug in tool such as a grinder when on it's own supply away from the light circuit

 

[Scotty Dive]

Buickanddeere - In the garage I have a seperate 15 amp light circuit, a 15 amp general purpose circuit and a 20 amp general use circuit besides the 50 amp 220V. Are you suggesting I take a branch circuit off the 220V 50 amp to a small panel dedicated and hard wired to just the compressor? If so, would a 40 amp breaker be too large for the 3HP compressor motor? I do not want to run another circuit from the panel if I can avoid it - just too far and a royal pain to run it.


Spoke to Longevity this morning - seems they sent the wrong plug (or forgot to remove the plug before shipping to me) And the electrician just matched up the receptacle to what was on the welder. Will fix it with this:
http://www.grainger.com/Grainger/LEVITON-Receptacle-5HZN0

 

[LD1]

I cannot believe a licensed electrician would wire that plug to a 220v breaker without questioning it and suggesting you buy the right stuff for the welder end AND wall plug.

I would also run a separate circuit for the air compressor. DO you have space in your breaker box to add another double pole breaker??

 

[Scotty Dive]

That is probably my fault - I told the electrician that I wanted an outlet to match up with the welder - I assumed that it came correct from the factory. I do have the room in the panel, but its almost 100 feet of wire through some very difficult spots to gain access. The 220v out to the garage is 50 amp and the welder calls for 30 amps and the compressor needs 15 amps. Which should not matter since I planned on only using one (and allowing only one) or the other (welder or compressor) to be run at any given time.

 

[radioman]

That plug looks just like my RV plug. Its just for a higher amperage use at 120v.

If a licensed electrician did it, Run if you try to hire him again.

Next- you need to pull cover off your breaker panel and look at the wires going into the breaker for that outlet. two ? or one? If one then you only got 120v. If you have two black or one black and one red then its 220v. While you are at it -check for both white (neutral) and ground screwed in bar at top. Should be there.

Which welder do you have and which compressor are you hooking up?