The overplanned shop/garage

[carcentric]

I wanted a 24' x 24' (2nd shop/garage) built when we moved here year before last, but the setback from the property line required that its depth be decreased to 22'. In the several months it took to get permits, I planned and replanned the siting, electrical, layout, etc. for hours on end. What I ended up with is at http://www.carcentric.com/shoplayout.gif - if it is too small to read, click the expansion box in the lower right corner.

Most everything turned out as I'd planned - I'll post pix of the details I'm proudest of in this thread later.

The only fly in the ointment so far is using my Hobart AirForce 250A plasma cutter. It's rated as requiring 20 amps (120 volt), and it used to work fine on my 20 amp circuit breaker in the shop's subpanel, but it's started tripping the breaker - at first after using it a while, but now as soon as you pull the trigger. The Hobart-authorized repair shop can't find anything wrong with it, and the geniuses at Hobart suggest I replace the 20 amp circuit breaker with a 30 amp one and install a new dedicated outlet with 10 guage wire (all wiring is currently behind taped, sanded, and painted drywall, so this is "a big deal").

I guess Robbie Burns was right, "The best-laid schemes o' mice an 'men
Gang aft agley . . . ."

 

[Bradley Miller]

I don't know what else you've looked into so far, but I'd check your line voltage also. I had a problem a few years back with a hot tub that was kicking off and not working exactly right. When I started measuring line voltage, I called the power company and had them take a look. They changed out the transformer by my house, the old one was weak plus the power requirements over the years had changed. Once upon a time, houses had one or two TV's, no computers, and etc... Over the years we've just been adding more and more gadgets (and garage toys) and power requirements didn't figure that in. (?)

 

[bmwpower]

I would try to stick a 30A breaker in temporarily to see if it fixes the problem. Assuming there is nothing wrong with the unit, this should be fine to do. Make sure nothing else is running on that circuit while you're testing.

I've had similar problems with my compressor and popping in a 30A breaker fixed the problem. Plasma cutter do not have the same startup draw as a motor does, however.

 

[Bradley Miller]

Also, I'm assuming here, but trying to help out . . . try using another breaker or outlet and see what happens. I know that breakers can get weak over time, so that and/or a voltage drop could be an explaination.

 

[914forme]

I guess Robbie Burns was right, "The best-laid schemes o' mice an 'men
Gang aft agley . . . ." [/QUOTE]

Wow old timer long time. You used to post on Rennlist. Okay first your question then we can talk cars.

Wire a temp line out of the sub panel and see, it won't meet code, but you just hang it out the front and see if the plasma fires off, if it does use it to cut a knock size hole in your front panel. Just kidding.

But if it does work, then swap the temp circuit with the questionable breaker. If it still works, replace the plug with the one your using, and narrow it down. Hopefully it is not the wiring. If it is it is time for some conduit.

Okay cars, I know you parted out the 914 Lite project awhile back, what you into now. As you can see from my calling card I am still into the 914s

BTW, what low lift are you using and how well did it work with the 914 for engine removals etc...

there is something to be said for having run extra conduit or even just running conduit from your panels into your space.

Take care, Stephen Jacobs

 

[JMURiz]

Okay cars, I know you parted out the 914 Lite project awhile back, what you into now. As you can see from my calling card I am still into the 914s

Wow, I remember that car, cool stuff. BTW, I don't think there is any way to overthink a garage layout!

 

[carcentric]

Many replies to many responses (thanks!):

LINE VOLTAGE (Bradley Miller). Is what you're suggesting a simple matter of plugging a VOM into the outlet, or do I need some specialty device to monitor voltage over time?

STARTUP DRAW (bmwpower). "Plasma cutter do not have the same startup draw as a motor does." This particular plasma cutter has an onboard air compressor that kicks in when the torch trigger is pulled, so there is a big draw then (the cooling fan runs continuously, but it's a little draw).

THINGS TRIED (Bradley again). I did try a 2nd circuit (with outlet only 2' from the subpanel - same problem. All the wiring, breakers, panel, etc., are only a few months old so "weak over time" wouldn't seem to apply. If it matters, the box and breakers are Square-D QO series.

CARS, and a trike (914forme). My avatar shows four current projects but the full write-ups, drawings, and pix are at my site: http://www.carcentric.com

LOWLIFT (914forme). It's the Bend-Pak LR-60 - absolutely fabulous for 914 drivetrain drops (with a long-frame floor jack to lower the engine/trans). The lifting ram is at one end, so it was not as good for 944 clutch replacement since the engine and clutch are at one end, the transmission is at the other end, and a torque tube connects all that. It's sturdy and stable, though, and only about half what a 2/4 post lift costs.

 

[MXtras]

I would suggest re-checking the tightness of the lugs in your sub-panel - both at the main feed and the panel. In the panel, check the tightness of the wire to the breaker. I will usually re-tighten all connections a few days after doing any wiring - they seem to loosen up shortly after the first time the wire is crushed. Just a thought.

And always upsize on the wire! Day late and a dollar short, I know.... It's my preference to consult the NEC and if I am in the top of a range I will go to the next larger wire size to minimize the potential for some of the issues you are having. For high draw circuits, bigger IS better.....except on your wallet.

BTW - have you seen how much wire has gone up recently? The price has doubled since this time last year!

Scott

 

[MXtras]

Also - if the device is rated to pull 20 amps then a 30 amp breaker would be appropriate - but then your wire is too small. If it worked before and now it won't and the equipment is fine, then I agree with the weak breaker theory.

Scott

 

[Bradley Miller]

If you sent it for service and they didn't find anything wrong, then voltage is something I'd suspect. A good VOM (digital) would probably give you a good idea there, but for 100% certainty, the power company could look also. I'm not an expert here, but just relaying what happened in my case. I was running a 120 volt portable hot tub and was having problem with it shutting down. (I didn't have too many options on moving circuits or that since it was full of water.)

 

[MXtras]

I agree - based on what he has said so far, I would doubt the equipment is at fault.

Scott

 

[carcentric]

I'll do the VOM check and call the power company to see if they can come out for free and check it, too.

In the meantime, I've attached a couple of photos of design features I'm very pleased to have thought of.

 

[Cody 82 zxt]

In the meantime, I've attached a couple of photos of design features I'm very pleased to have thought of.

Wow, I really like the idea of the small windows for light but, much more secure than regular windows. Wish I had thought about that!

 

[carcentric]

If you sent it for service and they didn't find anything wrong, then voltage is something I'd suspect. A good VOM (digital) would probably give you a good idea . . . .

Since the service center couldn't find anything wrong with the plasma cutter (on their high amp circuits), they charged me their hourly shop rate plus "shop supplies" for checking it out. If there had been a problem, it would have been free (under warranty)!

How's 118.6 volts? I got that reading at the outlets 4-5 times about an hour apart each time. And just now, with our electric heat pump running full tilt in the house, I got 117.3 volts.

MDN

 

[neblinc]

Either increase the breaker size, or see if a time delay Square D 20 amp breaker is available.

Randy

 

[carcentric]

I squeezed the two 15 amp lighting circuits onto one tandem breaker and put a new 30 amp breaker in the hole that was created. I then ran 10/2 Romex a couple feet to a single "trailer outlet." Now I have to use a 25' 10/2 extension cord to reach all areas of my little shop . . . .

Oh, well. Back to my shop details. This shows how I covered the shop light cords. Tray sheek, no?

 

[Bradley Miller]

I like that idea . . . I've got lights up and cords running here and there. One day I envision lights without plugs that actually have wiring hidden . . .until then, I'll do something cool like this.

 

[Dodgepu360]

if your drawings are over planing I dont know what you call what I am doing
I have been making a 3D model of how I want to lay out my shop in SolidWorks

 

[carcentric]

if your drawings are over planing I dont know what you call what I am doing
I have been making a 3D model of how I want to lay out my shop in SolidWorks

If I'd had 3D software, that would have been simpler than what I did: 8 elevations (4 inside, 4 outside) and a plan (overhead) view with each change requiring modification of at least three views (by hand, not updated automatically).

 

[Rrumbler]

Nice garage!! I hate you organized guys.

In reading about the problems with your plasma, I have a few comments.

118 volts is well within the acceptable range for delivery voltage (usually, 110 to 130 volts, +/-), so you probably won't get much help from them.

If your machine draws 20 amps running, it will most likely trip a 20 amp breaker on startup. Checking it with a clamp on ammeter with a data hold feature would tell you a lot. It is quite possible that your machine is running right on the ragged edge for a 20 amp circuit, and if the line voltage drops for any reason, the amperage will go up, and possibly overload the breaker. Your only solution, in this case is to upgrade the circuit to a 30A with the related wire size increase - not what you want to hear, I'm sure.

If you have checked the connections for integrity, all that you have told leads me to these conclusions. Good luck with it.

 

[jim dillon]

It may be something that you have tried but I had the same problem. I have two dedicated 20 circuits for my heater and I used the heaters for two winters with never a problem. When I tried my plasma cutter I would barely start the cut and it would blow the breaker. I went out and bought a 30 amp breaker but before I installed that I tried changing the outlet to a 20 amp outlet that would accept the twenty amp sideways plug or a standard plug and I haven't blown the breaker since. The thirty amp breaker is still sitting on the top of the panel just in case-Jim

 

[jilt]

You might want to try using a time delay breaker. I'm not sure if they make such an animal for residential use though. I have used them in industrial applications. Usually you will get a spike in amperage draw in the first second of start-up and then it will level out and stabilize. The time delay breaker will accomodate this spike and not trip until after its set time. (I think some models can be set with a dial but I cannot remember for sure) You should put an ammeter on the unit and watch it during startup to see if this will work. I would pop a 30 amp breaker in just to do the test to see what the actual draw is at startup and then see where it levels out to after it is running. This should tell you if a time delay breaker will work for your application. Hope this helps.

 

[VDubJoe]

I work for Progress Energy down here in Florida. As a trouble shooter. We have a voltage requirement of 115/126. The best way to ck is to put a amp meter on it so you can see the startup load. And also watch for a voltage drop. Id definatly call the power comapny to ck your conn and do a load test at the meter. Just call and say your having flickering lights. I find loose conn to be a big problem at the meter and in the panels. Good luck.

 

[Silver Lexus]

Looks like a nice plan. I wish I had some natural light from windows.