View Full Version : Does this shop wiring make sense?

Dave Chrudimsky
02-04-2008, 10:39 AM
So, I have two boys (16mo and almost 4y) and a shop space. I really don't want them to play with the machines, especially as they head towards their teenage years, without my express permission and supervision. To this end, I'm thinking about installing a safety switch to the circuits that control the heavy equipment, dust collection, and general 110 outlets. Lights, AC, and compressor would not be on this switch.

Here's the detail: I'm starting with a 100Amp subpanel in the shop, and am thinking about using a 240v 60Amp circuit breaker to the safety switch. The safety switch could be locked with a padlock, and high enough to keep it from children's probing fingers. I would engage this when I get into the shop, and turn it off when I leave. I'm assuming the safety switch does not need to be fusable. The switch then feeds another circuit breaker box with roughly four circuits: a 240v for large equipment, another 240v for dust collection, and 2 120v for all of the outlets in the shop.

Does this make sense? Does anyone else use this type of arrangement? Anyone have better ideas?


Eric Gustafson
02-04-2008, 11:05 AM
Why not just get a lockable 100 amp box and turn off the breakers you want. It would be simpler and less costly.

Art Mann
02-04-2008, 11:05 AM
Certainly sounds reasonable to me, for whatever that's worth.

Art Mann
02-04-2008, 11:08 AM
I thought about just using the breaker switches too but I don't think that breaker switches are designed for daily use.

Dave Chrudimsky
02-04-2008, 11:13 AM
Why not just get a lockable 100 amp box and turn off the breakers you want. It would be simpler and less costly.

This did occur to me, but I wasn't convinced that the breakers were built to handle the mechanical stress of being switched on and off every day.

Roger Ronas
02-04-2008, 11:24 AM
Breakers can definitely be switched on/off on a daily basis.

Used to run a shop, and I know many others, that only switch breakers and have no wall switches.


Mick Zelaska
02-04-2008, 11:33 AM
I believe the sub-panel will have a main cut-off that shuts off power to all breakers. Shut off the main then lock the panel.

Even if you turn individual breakers off just replace them in 15-20 years if they wear out. They're fairly inexpensive.
Check to see what manufacturers breakers are stocked at Lowes or HD and use that manufactures sub-panel so replacement breakers won't be a problem.

Anthony Whitesell
02-04-2008, 11:34 AM
Let me see if I'm reading this correctly.
100 amp sub panel with "4" circuits for the 1.lights, 2.AC, 3.compressor, and 4.60 amp subpanel for the shop tools. The 60 Amp circuit in 60 Amp panel would have its own breaker from the 100 amp to the 60 amp subpanel.

With the single 60 amp breaker to the shop subpanel you could use a lock-out/tag-out device for circuit breakers, such as

But circuit breakers do not like to be used like switches. That will shorten their life and reduce their trip rating.

You could install a lockable disconnect in a box between the main panel and the sub panel.

Either something like this mounted in a enclosure

or this

These are both rated at 60 amps and they make higher.

Just make sure the switch is rated higher than your subpanel draw.

I would also swing by an electrical store and ask what options they have. When you mention shop safety and kids, I'm sure they will show every option they have on the shelf.

Rod Sheridan
02-04-2008, 11:37 AM
Dave, I installed a 30 ampere locking disconnect switch that was fed from a 20 ampere 2 pole breaker.

This turned off all the 20 ampere 240 volt receptacles, and the 20 ampere 120 volt receptacles. This is the only feeder in my shop, except for the dedicated circuit to the cyclone, and the circuit to the compressor.

I wasn't worried about the kids running the compressor, or the cyclone.

I used to lock it when the kids were young, now that they're in their twnties, I don't.

I liked the idea of being able to prevent un-athorized use of the machinery in the shop.

Regards, Rod.

Heather Thompson
02-04-2008, 11:57 AM
When I was little, maybe nine or ten, started using my Dads tools when he was working at the tool and die shop (he made the faceshield for the first astronaut on the moon). My father taught me a great respect for machines, flowing water (rivers-drift fishing), and snow in the mountains, I am still alive today. I would have been glad to see my son follow me into the workshop (he is 21 now), last summer I showed him how to replace a window in his car, he told me that he missed alot. My ex does not know how to change a light bulb, he makes a healthy six figures but is as D__B as they come. Teach your children well, there are things that will be more dangerous for them to face, peer pressure, drugs, alcohol, etc.


Lee Koepke
02-04-2008, 12:05 PM
I installed one of those non-fused disconnects for my TS. Much easier for me to shut the power when changing blades, etc, as the power cord and plug were in a difficult to get to location.

02-04-2008, 12:14 PM
I wired my shop with that in mind. Similar idea to what you're proposing. The lights and DC circuits are fed by the main panel and a subpanel feeds the rest. I had to do it that way for breaker count, but I chose circuits on what made sense. I can switch off my entire 60A subpanel easily if necessary. But, I find I don't. So I installed a cipher type lock on the door. Now they can't get in unless I'm there.

Dave MacArthur
02-04-2008, 1:10 PM
I wired my 100A subpanel with "kid safety power cutoff" in mind, and used a subpanel with a Main CB of 100A on it(came that way from HD as a kit). The subpanel is fed from a 70A CB. When I priced 70A cutoff switches to be placed between the two panels, it turned out they were more expensive than the 100A main breaker in the sub. Since the 100A CB in the sub will never be "tripped"--just the sub panel circuits, or the 70A feeder in the original panel-- it provides no safety function really for the sub panel. Therefore, I used it as a switch to turn everything on/off. If it degrades that CBs trip rating, no worries--that CB could never be tripped due to lower CB on both sides of it. And if it wears out, I can buy a replacement 100A from HD for < half the cost of a real cutout sw.

Jim Becker
02-04-2008, 2:11 PM
If I'm not mistaken, a lockable cut-off switch box between the main and the sub panel is the right way to kill all the machine circuits. A breaker, itself, isn't supposed to be used as a general switch. If you want to see an example of such a switch, there should be one near your outdoor A/C unit.

Wade Lippman
02-04-2008, 5:02 PM
Some breakers are designed to be used as switches, and others are not. If you can get the right kind, you are all set!

It might be easier to teach them not to go in your shop; that's how I handled it.

Dave Chrudimsky
02-04-2008, 6:11 PM
Thanks for all the inputs, I'm amazed that I got so much feedback in so little time.

Going the circuit breaker route will mean that I have to find a lockable door on the 100A subpanel that's already installed. I don't know if that's easy or not. I'll look into that a little more.

As for Heather and Wade's concerns, I agree, and do intend to teach my children safety and respect for tools. I hope that they are interested enough to learn all sorts of practical skills for life. Even so, I'd like the added insurance that when I'm not around, a lapse in judgement won't result in loss of limb or life.

02-04-2008, 9:01 PM
SIt might be easier to teach them not to go in your shop; that's how I handled it.

My kids are pretty good about it. Some of the neighbor kids ... not so much. Thus the cipher type combo lock on the door. I'd just rather not have them in there with or without power.

Bob Wingard
02-04-2008, 10:12 PM
I would tend to agree that breakers are not generally designed to be utilized as switches .. .. .. in this instance they aren't. The breakers should not be used to power-up your tools, but if the tool is OFF .. .. it is perfectly acceptable to then turn off it's corresponding breaker. It would then be a function of how many cycles before it mechanically wears out .. not how many times you have run an arc thru it. BIG difference !! !! !!

dave rollins
02-04-2008, 11:11 PM
Check at an electrical supply house and see if there are some SWD (switching duty)rated breakers for your brand of panel. Very common in comercial and industrial panels. I have never looked to see if they are available for residential panels.
Hope this helps.

Michael Lutz
02-04-2008, 11:38 PM
My subpanel powers everything in the shop except for the lights. When I am done for the day I shut off the sub-panel main breaker. The actual trip breaker is in the main breaker, so the main breaker doesn't have an electrical function except to shut off power.


Randall Davis
02-05-2008, 2:01 AM
Some breakers are designed to be used as switches, and others are not. If you can get the right kind, you are all set!

It might be easier to teach them not to go in your shop; that's how I handled it.

everybody knows a kid that wants to find out why if he's told not to do something. Fotunately I did'nt have any like that. I think some type of disconnect is a good idea. In MI a breaker is a suitable means of disconnect.

Brian Dormer
02-22-2008, 1:44 PM
I'm thinking along the same line as Jim -

I don't know what code says (it should be ok - but check with an inspector to be sure)

Why not get a A/C cutoff switch (same thing thats outside next to the compressor) and use that? It's still probably not rated for daily use - but it's got to be better than using the main breaker.

Of course, electricity is only ONE of the hazards for little fingers in the shop. I put a keyed knob lock on the door to the shop. The key is kept on a nail up higher than the kids can reach and they know that the shop is off-limits. I've never had an "intrusion".

If I was really worried about it - I'd just put they key on my keyring and keep it with me. Or - buy a cypher-lock (Unican) off ebay and use that.