Plugging in a Speedaire compressor: what voltage?

by Fred
(Douglas City, CA)

I have an older Speedaire compressor. The model number is 3Z355B (sorry six characters not five as posted). It is a two cylinder, single phase compressor that can be wired either 230V or 115V.

The plug ends are perpendicular to one another in addition to the round tipped ground. I am trying to determine if this is wired 220 or 110.

Obviously I don't want to plug it into the wrong outlet. I picked this up used years ago but when my other compressor stalled I decided to resurrect this one. Can anyone help?

Bill says... don't worry!

Hi Fred.

No, I'm not an electrician, but I have to believe that you can't plug a 110 VAC plug into a 220 VAC receptacle, and vice versa, as the two types of plugs are incompatible, in order to help people identify the two.

Have you a clothes dryer? Have a look at the plug for the dryer. Clothes dryers are often 220 VAC, and if yours is, you will see what I mean about an entirely different plug.

Plug your compressor into a 110 VAC receptacle, and see what happens. Make sure the tank drain valve is closed, and of course, that there are no obvious issues with compressor maintenance, such as bare wires, wires off... you know, that sort of thing.

Also, look at your compressor plug, and the 220 receptacle behind your dryer. If the dryer is 220 VAC, then your compressor plug, as I interpret how you've described it, just won't fit.

Last, I believe if the compressor is dual wired inside, you need to make a change in the supply plug to provide the appropriate power.

Anyone else have any suggestions? And Fred, thanks to him for visiting this website and for writing in.



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Aug 06, 2010
speedair model 3z355b
by: Herb

I have the exact compressor and I have always run it on 240v. I also want to sell it , thinking 200 dollars. it is in perfect cond. and looks good.What do you think?

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Speedaire Model 5Z404-2 air compressor - external shut off

by Gary Hughes
(Fresno, CA)

I have one of these installed at a Bakersfield high school where it will be used for shop air. The H.S. District wants to shut the unit off on the weekends.

I proposed a relay that would interrupt the control circuit to the starters. But after looking at the unit with dual compressors and an alternating relay, it looked like this might be tricky.

The control contractor suggested putting an additional starter upstream of the whole unit. That way we wouldn't be getting into the manufacturer's control circuit.

The starter may actually be cleaner in that we don't touch the air compressor. Will shutting off the unit with an additional starter, mess up the control circuitry of the air compressor?

Or would the relay be a better way to go?

Since I'm here, how often should these compressor tanks be blown down at the drain to exhaust moisture in tank?

The control company wanted to install an autodrain valve and blow it down periodically.

Thanks for your help.

Mechanical Engineer

Bill says...

Gary thanks for the visit and questions.

I'm not an electrical guy, so I would take the advice of a qualified electrician on how to properly shut off power to the units.

I like the idea of an automatic drain. I've got info on them on this site, but seem I've left the link off the sitemap. I will fix that shortly.



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