While we are talking about 220v circuits

[John Cooper2]

I have a 18' x 32' shop that is serviced by a 60amp sub panel. While that doesn't sound like a lot it really is fine for my purpose (so far).

Adding a larger service is not really an option and I don't think it is really needed, my question is this.

I am getting ready to upgrade my Air Compressor and at some point I will be installing my dust collector. I feel comfortable running either by it's self, but I would not want them to come on at the same time. So is there something like a A/B switch for 220v circuits so I could run one or the other, but not both at the same time?

thanks in advance.

[Sam Layton]

Hi John,

If you don't want the compressor to come on while you are running your dust collector, just turn off the compressor. I have a fused disconnect at my compressor, in addition to the compressors on off switch. I don't know what type of compressor you are looking at. If you get a 60 gal tank, your compressor will not come on that often. After the compressor is full, just flip the disconnect and if you need a lot of air, flip it back on. The fused disconnect switches work very good. I have them on several of my tools. Eventually, all machinery will have it's own disconnect.

Sam

[Curt Harms]

I have a 18' x 32' shop that is serviced by a 60amp sub panel. While that doesn't sound like a lot it really is fine for my purpose (so far).

Adding a larger service is not really an option and I don't think it is really needed, my question is this.

I am getting ready to upgrade my Air Compressor and at some point I will be installing my dust collector. I feel comfortable running either by it's self, but I would not want them to come on at the same time. So is there something like a A/B switch for 220v circuits so I could run one or the other, but not both at the same time?

thanks in advance.

Disclaimer - I am not a pro sparky. I think you could do this with a double pole double throw relay of adequate capacity. 2 conductors from the load center to the "line" connections on the relay. One "load" position on the relay powers the compressor, the other powers the dust collector. They could never be powered at the same time. I've never worked with double pole double throw relays so I'm speculating here, thinking in terms of a double knife switch.

Here is a section from McMaster-Carr's catalog http://www.mcmaster.com/?m=true#catalog/118/855/=ii2fij

A double throw (DT) switch can be wired to be normally open or normally closed, offering greater flexibility. Another advantage of a double throw switch is that it can shift power between devices.

Here's a page with some choices

http://www.mcmaster.com/?m=true#high...relays/=ii2mfl

The middle of the page has some infrequent cycle high amp relays. The top of the page devices are rated for 20 million cycles, probably a little overkill for home shops.

[Joseph Tarantino]

john.....i find that woodworkers almost always overestimate the amount of service they need for their one man hobby shops. 60 amps of service is more than adequate to handle almost anything you will come up with. my shop has a 30A subpanel. i run a 3hp 40yo unisaw (dual voltage, 32A, 110v; 16@, 220v beast of a motor wired for 220v) and a delta 50-850 dust collector (dual voltage, 12A, 110v; 6A, 220v wired for 220v) at the same time with no problems at all. so concern about a compressor and a DC operating simultaneously, unless you're talking about some seriously heavy draw pieces of equipment, is probably unfounded.

[John Cooper2]

Sam,

It has a 80 gallon tank so I suspect it will not be cycling very often. Just have to make sure that I have no leaks so it doesn't bleed down over time.

I will need some form of remote on / off as the compressor will be buried in a back room. Was going to put it outside under a cover, but I have a corner in a back room that is pretty much dead space and thought it would be a good place for the compressor. Will have to rig up a remote drain as well because of access issues.

Joseph,

What I want to avoid is 60 year old Unisaw with a 3 hp Lesson Motor, Dust collector 3 hp Motor and Air compressor (7hp) (specs say 31.4 amps) coming on all at the same time. I think two at a time would be fine, but all three is something I want to avoid if possible. I also don't want the Air Compressor coming on in the middle of the night.

Thought about just wiring them up as is and using the breaker as a "switch" but found out that is not a great idea. Guess breakers only have so many on / off cycles in them.

Curt,

Had not thought about a relay, will look more into that option. DC and Air Compressor are outside of the room so some type of "remote" switch would be great. A relay would allow me to run a low voltage line to switch.

[Jason Roehl]

Rather than a manually-switched DPDT switch, I would think you would want a relay wired such that when the DC is on, power to the compressor is cut off. If you're using the DC, my guess is that you wouldn't need the compressor--and, since you said it would be in a remote location, that would be the one you want to have the automatic operation. Once the DC is turned off, the power to the compressor is restored so that it can cycle as necessary.

I think the 7230K873 is what you would need:

http://www.mcmaster.com/?m=true#gene...relays/=ii5c40

[Don Jarvie]

How much space do you have in your panel? Enough for 2 lines - 4 slots? That would probably be the best so they could work at the same time if necessary.

[John Cooper2]

Jason, Thinking the relay is the way to go, this one only handles 10a. Spec on compressor says 30a which I find hard to believe. Going to take a better look at that when I get it in two to three weeks.

Don Panel is maxed as is. I have one 220v circuit that will need to feed both of these units.

[Sam Layton]

Shop Dust collection remote switch 001.jpgShop Dust collection remote switch 004.jpgShop Dust collection remote switch 007.jpgShop Dust collection remote switch 010.jpgShop Dust collection remote switch 012.jpg

[Sam Layton]

Sorry, I tried to edit the above photo's without success. The below goes with the above photo's.

John, if you want to have your compressor in another location, you could still mount the disconnect in your shop in a suitable location. In addition, if you want a remote control, I would recommend a contactor switch. In fact, you could have two, one for the dust collector, and one for the compressor.

Below are photo's of my setup. With the contactor switch, you use a cheap 110 remote, (I purchased mine from Radio Shack) to activate your 220 contactor which turns on your dust collector. No expensive 220 remote controls. I do not like to leave the remote active all of the time, in case a stray single comes along during the night and turns my system on. So I wired a 110 switch to give my remote control power. In addition, I wired in a night light so I know when my system is active. So, when I close the shop for the night, I can see the light to remind me to turn off my system.

Also Photo's of my disconnect switch on my compressor. I also have an automatic drain. Every morning when I go in the shop, I automatically open the valve and drain the water...

[John Cooper2]

Sam,

I am liking your set up.

I am pretty sure I have some 50a solid state relays laying around that I forgot about until I saw your pics.

They are triggered by 5v, I can provide that with a wall wart. Like your idea of a nite lite as well, going to rig up something similar.

Just spent a couple hours cleaning up the room that it will go in. Made progress for sure, but a long ways to go for sure.

Going to start digging to see if I can find the relays and get working on that.

Thanks for the pics and ideas

[Bruce Wrenn]

Have you heard about multi-wire branch circuits? They use a double pole breaker (220V) along with a neutral. This would allow you to create a second 220 circuit. I use these on all my machine circuits. One of the hots passes through a sensor in panel that controls DC. You could do a reverse. Have sensor turn off air compressor instead of turning it on.

[Curt Harms]

Jason, Thinking the relay is the way to go, this one only handles 10a. Spec on compressor says 30a which I find hard to believe. Going to take a better look at that when I get it in two to three weeks.

Don Panel is maxed as is. I have one 220v circuit that will need to feed both of these units.

If you wind up buying a relay, I'd pay attention to the horsepower rating as well as ampacity.

[John Cooper2]

Bruce, I have not heard of that, will look into it.

Curt, Good point, will do

[Joseph Tarantino]

john......ok, 31+A @220 in a home hobby shop for a single piece of equipment does, in my world at least, qualify as a serioiusly heavy draw unit, so my comments aen't relative to your situation. it's probably not needed, but this link did a good job of reviewing the particulars of inexpensive remote controls and higher amperage contactors. perhaps some of it may be helpful to your plans:

http://www.beautifulwood.net/html/wireless_dc.html