Several Questions...leading to Garage Subpanel

willstutely · 08-24-2011, 02:45 PM

I recognize that an often discussed topic is the garage subpanel. I imagine some guys get sick of dealing with it. My problem is that there never seems to be a situation that matches mine, and I'm hesitant to mess around with stuff that can kill you on partial info... thanks in advance for your longsuffering...

Here's what I would appreciate help on:
- Determining my current power service situation
- Installation of a subpanel in my garage

Here's the current situation:
For my main panel I have a bulldog pushmatic. I have no idea what the actual service is as there isn't a main breaker. In the attached picture you can see that there are three double pole breakers. According to a faded sticker on the panel, those three breakers control all of the circuits below. They are 40 (top), 60 (middle), and 50 (bottom). The top appears to only control the circuit that my stove in my kitchen is connected to, the middle powers a subpanel in my laundry room (will get back to this point), and the bottom controls all of the other circuits in the house.

First question(s): Is this panel then a 150A panel? Why wouldn't there be a main?
I'd love to eventually replace this old thing with a modern panel that offers me more flexibility. Cash is an issue at present.

Continuing... the subpanel that is fed by the middle breaker (as seen in the second image) is where I would like to draw power for the breaker in my garage.

My plan for the garage is a 60A panel. From what I've read this should be adequate for my intended use, which is a workshop...mostly woodworking. I won't have any 220v applications, and at any given time there will only be two things running apart from lights, 5,000btu window A/C, etc...table saw or other similar tool, and dust collection, which is rigged up with my shopvac.

The subpanel currently runs a couple of circuits that power lighting, and my washer and dryer. There are two 30A 220v circuits on it currently, but they are not actually in use, nor will they be.

Is it ill-advised to run a 60A subpanel out of this other subpanel? Would it be better to run those two 30A circuits out to the garage as separate sources of power, one for the shop tools and the other for lights, etc.? I could bring them into a box in the garage so I can split them into separate circuits.

If I'm effectively setting up two 30A panels in my garage (but in one panel), what gauge wire should I use? In total the run will be 50'. Also, the power out to the garage right now (which is off a 20A breaker in my current subpanel) is via a cable suspended above ground. I'm planning on doing the same thing as I don't really care to bury the cable. To do so would mean cutting through a concrete walkway...not happening.

Sorry for being wordy...never figured out how to economize myself.

Code05 · 08-24-2011, 02:56 PM

1 You sub panel seems to be wired wrong, looks like a 3 wire feed. Grounds and neutrals in same bar.

2. You can not feed a detached structure with 2 supplies.

willstutely · 08-24-2011, 03:08 PM

Re: 1. Can't speak to that...was like that when I bought the place a few years ago.

Re: 2. Because...?

Jim Port · 08-24-2011, 03:09 PM

I suspect what you have is a split buss panel. With these the top 6 (max) breaker shut off the power to the panel. To determine the ampacity you would need to find out the size of the cable feeding the panel.

As was said above you can only have one feeder to the shed. The problem with taking power from the sub might be a tripping breaker should you try to use too much power between the shop and the laundry panel. You would be splitting the 60 amps between the two panels.

willstutely · 08-24-2011, 03:19 PM

So the single feed is a code thing, I'm assuming. Is there a rationale behind that?

Here's an option that occurred to me... considering my subpanel in the laundry room doesn't use anywhere close to what that panel could handle at any given moment... what if I were to swap out the top and middle breakers on my main panel and then use the original one for the subpanel for my garage panel (the middle), and then the top one for my laundry room panel? The top one is 40A. I'd obviously just swap out the wiring, and not move the actual breakers.

In that case, what is the exact type of cable I'd need? From what I've read it appears as though #6 is what I'd need. So, 6-3? What type of cable for above ground suspension?

willstutely · 01-03-2012, 02:38 PM

Due to cash flow I've not been able to seriously start this project until about now, and there are other factors that are changing what I'm intending to do.

The sub panel that is feeding off of the 60a breaker on my main panel will now be using one of the 30a breakers for an A/C condenser unit to be installed professionally early this spring. Plus, I bought a 7 cu ft deep freezer that is running off a circuit from this panel.

That means that that sub panel will now be feeding:
- An A/C unit
- Gas dryer
- Washer
- Freezer
- a couple of circuits for lighting

At this point I'm not sure that I'd be able to pull anything from this panel to run to my garage to power a panel out there.

Mildly frustrating, as I really need to run power out to my garage. Any suggestions on how to accomplish that?

Thanks.