Garage/Shop electrical questions

[Russel De Arman]

We purchased a house about a year and a half ago, up til now I've been focusing on the house itself, but now I'm doing some garage/shop work as well.
It is a three car garage, detached, with two bays having 9' wide doors and one having an 8' wide door, all roll-up, original 1965 Overhead Door Co wood doors with press board panels; there is a framed wall separating the two larger bays from the smaller one. There are currently two outlets and two bare light fixtures, as in, screw the bulb directly into the porcelain base type fixtures.
I've checked the main panel on the house and the feed to the garage comes from a 40a (two 20a breakers tied together) breaker. Limited funds preclude just re-doing the entire system, but...there are some things that need to be fixed.
1. The feed from the panel to the garage isn't buried. The wires leave the panel and are in PVC the entire run (~35') and the PVC is barely under the ground.

2. I'm not sure what gauge the wire is; while the circuit is 40a, the wire looks small and I'm hesitant to start adding outlets and lights in the garage until the wire is properly sized and properly buried.

3. I'm satisfied for now with a 40a service, but if I'm going to run new wire, properly, I'd like to run large enough wire that later I can hook it to a 60z service.

So, again, since I'm on a tight budget for this, I'd like to dig the trench myself, and buy/run the wire myself and have an electrician come in just for the hook-up; what do I need?
Thanks for any advice,
Russel

[Mike Henderson]

I assume you mean two 20 amp breakers with the toggles tied together. If so, you probably have two 120V 20 amp circuits with a shared neutral.

And the wire is probably sized to that 20 amps, most likely 12/3.

To do this correctly, you probably should put in a sub-panel and have a 50 to 60 amp line run to it. That means a double breaker in your main box (two 50 or 60 amp breakers with the toggles tied together) and four wires between the main panel and the sub panel (two hots, one neutral, and one ground), wires sized for the breakers.

I would suggest you seek some help from someone familiar with house wiring before you make a mistake.

Mike

[Lee Schierer]

Unless there is another breaker box in the garages that you didn't mention, you have a dangerous situation with the two breakers toggled together. That double breaker is supposed to control a 240 volt circuit. 40 amps is far too big a breaker to have connected to a couple of lights and two receptacles. I would suggest turning the breaker off until you can map the entire circuit and replace the breaker with two separate 20 amp breakers..

[Russel De Arman]

Thanks for the responses Lee and Mike.
Mike, yes, it is two breakers (both 20 amp) tied together. The wires from the garage come in from the bottom of the panel, the white goes to the common bar, the red goes to one of the two breakers and the black goes to the other breaker.
These wires are routed to the garage through PVC (maybe old plastic type conduit?) but it is exposed for most of the 35' run. They terminate in a waterproof box (single gang size) outside the garage at 4-5" above ground level and are wire nutted to to the wires that are in the garage.
No permits have EVER been pulled on this house, the city keeps records back to 1980.
Lee, hopefully it was just my poor terminology that caused the 'dangerous situation' call...but if not, tell me again and I'll turn that breaker off.
Russel

[Rollie Meyers]

2-20A breakers with a handle tie does not equal 40A as they are not doubled, it's 20A breaker, if more circuits are desired then a panel will need to be installed w/ a suitable feeder because only one circuit is allowed to be run to a outbuilding, & the existing multi-wire circuit complies w/ that.

[Lee Schierer]

Lee, hopefully it was just my poor terminology that caused the 'dangerous situation' call...but if not, tell me again and I'll turn that breaker off.
Russel

If it were my house I would replace the joined breaker with two independent ones. You don't want one circuit tripping the other separate circuit. I'm pretty sure if you do ever pull permits for the house, the inspector will make you change them.

[Rollie Meyers]

If it were my house I would replace the joined breaker with two independent ones. You don't want one circuit tripping the other separate circuit. I'm pretty sure if you do ever pull permits for the house, the inspector will make you change them.

For a multiwire circuit the handle tie is required.

[Lee Schierer]

For a multiwire circuit the handle tie is required.

Unless I have misunderstood, the OP said it is running two separate 120 volt circuits, not a 240 volt feed so no tie should be present.

[Mike Henderson]

Unless I have misunderstood, the OP said it is running two separate 120 volt circuits, not a 240 volt feed so no tie should be present.

Note that he said he had a black, a red, a white and a ground (post #4). He also said the red went to one breaker and the black to the other. With that configuration, he either has one 240 V circuit, or two 120V circuits on a multiwire (shared neutral) circuit. In either case, he needs two breakers with the toggles tied.

Mike

[Steve Meliza]

I'm not up to speed on the code requirements for buried service and outbuildings, so the following will be a bit generic and possibly wrong so you should verify with the requirements in your area.

1) You probably need to bury the PVC at least 12" if not 24". You'll have to study your local codes on this one.
2) The wire should be labeled somewhere on the outer sheathing, yours should say 12/3. If it says 14/3 or you can't find a label then you are wise to not touch something you don't have figured out yet. My old garage wiring was on 14/2 wire on a 20A breaker, I assume when they added a bunch of new garage lights to the existing circuit that the extra 5A draw was causing the 15A breaker to trip so they "fixed it". Good way to start a fire according to the licensed electrician that I mentioned it to.
3) Like Rollie said, you can only have one circuit to an outbuilding so the existing 20A multiwire branch circuit (assuming you do have 12/3 wire) is the best you can get without putting in a sub panel. It will allow you to have one 20A at 240V circuit and/or two 20A 120V circuits.

To get the 60A service that you would like you'd normally use 6/3 wire as it is rated for 55A and code allows you to up size to a 60A breaker. But you might want to up it to #4 as it will have less of a voltage droop and gives you a little overhead in case there are any de-rating factors at play. Once you figure out your tench depth and get it dug put in two runs of a generously sized PVC (1" to 1.5" should be plenty). One run will house your power cable and the other capped off for future use for telephone, TV, or internet cabling. Tis better to spend a little extra now and overkill everything than dig up and replace a marginal installation that isn't cutting it. In the garage put in a 100A panel with a breaker at the top and lots of empty slots for circuit breakers. The 100A breaker in the subpanel acts like a disconnect as it is rated too large to provide over current protection. Just make sure the ground a neutral buses are not bonded together as they must remain separate at the sub panel.

Don't be afraid to do the whole job yourself, I did when putting a sub panel in my garage. The inspector knew it was a homeowner job, but when everything at eye level was done correctly he didn't bother digging too deep and only had one minor correction for me to make at the new panel. When he came back for the final inspection I passed with flying colors. I'm no electrician but I did read a few books, including the NEC code book and the changes made to it by Oregon when they adopted it. If you completely fail an inspection around here you just pay $30 to have them come out again at a later date to inspect your corrections.

[Chris Padilla]

Russel...post some pics of what you have so we are clear what you are talking about. You've confused me pretty good with "double-breaker" talk so I'd like to be clearer.

[Julie Moriarty]

So let's assume you have a 2 pole, 20A breaker feeding your garage with 12 ga wire - 2 hots, 1 neutral and 1 ground. And they are run through PVC conduit barely below grade. I've never worked in a municipality that would allow PVC conduit to be buried anything less than 24" deep. Some require 36" with PCV. But most will allow 12" deep burial if you use GRC (rigid) conduit. I've even seen local codes that allow 6" depth for a dedicated load. Your local inspector will give you the right answer.

As for the size of your garage feed, it's good until you start tripping the breaker, as long as the wire is sized properly. On long runs, you need to factor in voltage drop (VD). That may mean you need #10 or maybe even #8 wire for a 20A feed. You need to know the distance, the wire insulation and whether it's overhead, direct burial or in conduit. The NEC has tables that help you dial in the right wire.

Since you're willing to dig the trench yourself, it's pretty easy to install PVC conduit. Some municipalities allow direct burial but you'll probably have to go deeper than 24". Again, your inspector can tell you for sure. Don't be afraid to call him or her. Many people mistakenly think that once they call an inspector they will come in and cost you a bundle trying to find problems with your existing system. I've never found that to be true and I've probably dealt with over a hundred inspectors during my career. Contacting the inspector is especially a good idea if you don't know your local code or aren't sure of your electrical skills or knowledge.

Personally, I'd run 1-1/4" conduit minimum if you plan to upgrade the feeders to your garage. The cost shouldn't be prohibitive and you'll be able to get as much as a 100A feed to your garage. Wire is where most of the cost is so you could upgrade to 40A now and if you need to go larger in the future, the conduit is there.

[Russel De Arman]

Well, after a LOT of reading in the past two days and a little more digging (figurative, not literal) into both my main panel and the garage wiring, I can update. Thanks for all the help and input thus far, by the way.
Here is a pic of my main panel, attached to the house:
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On the right side, the third and fourth breakers control the garage. I have also traced the wires...the red wire is connected to romex (not sure that's the right term, it's 1964'ish aluminum three wire cable in a 'cloth' type cover, which feeds one light fixture and one outlet; the black wire is similarly connected and feeds the other light fixture and other outlet.
So, I have two 20a circuits, each powering one outlet and one light fixture.
Additionally, in the picture, I have determined that the upper two right-side 20a breakers are not in use, they are labeled for a back room window a/c unit that is not in use; AND the left side bottom two 20a breakers are connected to a 240 outlet that is three feet from the main panel...I have no idea what the original owner used this for but I don't need, can't foresee a need for a 240 outlet in what is essentially a difficult to get to portion of the back yard.
For now, I can add lights and outlets within the garage and not worry about overpowering the circuits. And within a short period I will add a sub-panel to the garage, trench a proper line, and then add everything I think I need to the garage.

[Chris Padilla]

Ok, so in your main panel we have, all tie-barred together: Left side are 60, 50, and 20 Amp breakers; Right side are 20, I don't know (20 A according to you...works for me),and 50 Amp breakers.

I'm guessing the non-20 A breakers feed other sub-panels and/or a larger piece of equipment like a stove or electric dryer or maybe an A/C. The 20-A breakers visible in the pic and that you describe or probably wired as a multi-branch circuit (shared neutral). It is probably 12/3 wire (one black, one red, one neutral, and one green or bare copper...all #12 wire [the green or bare copper might be smaller]).

Anyway, you can replace the unused 20 A breakers with something larger (50 A and 6/3 copper or equivalent aluminum and you can feed a "garage" sub-panel) most likely. It will depend on what else is hooked to your main box and what they are powering to ensure the main line into the main box can handle the load. Note that you don't just add up all the breakers to figure out how much current you are pulling from the pole outside your home because you aren't likely to be maxing out everything in your box at the same time.

So what else is hooked up to these breakers?

[Steve Meliza]

This is not your main panel, this is a sub panel to your main panel.

Were you not able to determine the wire size feeding the garage?

The breaker feeding your garage should have the handles hard tied with something rigid like the other breakers in that panel are. If it were me I'd swap those garage breakers for the unused 20A breaker with tie and pull off that silly white wire tying the handles together. If you think it might be a bit before you work on the electrical then schmear a little Noalox on the aluminum wires before making the new connections. This should serve as a real-life example of the dangers of a multiwire branch circuit - they are not always done correctly.