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Garage Wiring issues

15K views 20 replies 9 participants last post by  jimmyfloyd 
#1 ·
Ok, I decided this weekend to add a motion light to my garage. This went well, but when I went to connect it with the power in the garage, I found the junction box packed with wire.

No problem, I'll just add a second junction box and clean up the wiring a little (been planning on this for a bit.) So I removed all the constant power and garage-switched only wires to the new junction box and left the 3 way wires in the original box, along with the source feed and the box connector wire.

Well, while doing this, I noticed something that didn't make me happy. My supply line to my garage is a single 14-2 wire. :eek::mad:

So, now I have moved re-wiring the garage up higher on my list. For now, all I really run out there is the lights, and occasionally a miter saw, but that's rare. The garage is detached, but close enough that I can run an extension cord from the basement dedicated tool circuit to the garage if I need to use any high load tools, or for an extended period of time.

My question is, what do I need to be looking at for when I upgrade? Here is what I have now.

100 amp panel.
1 15V circuit for the garage.
1 spare 220V from the old dryer (switched to gas) that the space could be used.

The garage is about 10 feet away from the house, on the side with the panel. The current wire goes about 7 feet across the wall and then outside, down into 1/2" conduit underground to the garage, and then in.

There are two options I am considering. The first being just run a 40-60V line to the garage, and get a small subpanel there. The second is have my box upgraded to a 200A, and then use the current 100A box in the garage as a subpanel with 100A going to it.

What items will I need to be looking to get to accomplish either of these tasks, and anyone give me a rough estimate of the cost?


Here are some pictures for reference. Here you can see the side of the house. The panel is inside under the meter, and the cable to the garage runs outside right next to the side door.


And here is the garage side of things. Currently runs inside, and then up the wall next to the side door to a junction box above the side door.


Thanks.
 
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#2 ·
There is nothing inherently wrong with 14 gage wire on a 15A circuit. Are you having problems? Does this trip the breaker when you use your saw?

An upgrade is fine, but don't just upgrade because your garage is fed with 14-2.

Does the 14-2 have a ground?

Why are you considering upgrading to 200a service?

Fill me in on why you want to do this upgrade so I can make some suggestions.

Jamie
 
#3 ·
Well, right now the whole garage is on a single 14-2. and there is no ground at the garage, just going back through the panel in the house.

Currently, I have two 4' 2 bulb t12 shop lights, a garage door opener, and two plugs on that. I added a 150W halogen motion light and 2 more plugs for additional lights, which are getting added. With just the shop lights on, and my miter saw plugged in, the light dim to almost out when I turn the saw on, then come back up, but not 100%. From a safety stand point, this is not good.

I also have an air compressor, and several other saws I would like to have plugged in so I can use them for my projects. I also plan on having a computer out there, and installing 3 more exterior light fixtures. There is also the possibility of 220V for a welder and/or air compressor.

If it were just lights, there would be no issue.

As for the 200 amp panel, I was only originally thinking of a 150 amp panel, but was told it's essentially the same cost here to do 200 amp. I have used up all my circuit spaces in my current panel, and have several circuits that are overloaded (thanks to being an old house) I plan on re-assigning some of these circuits, so the extra space will be helpful as well. Sure 200 amp may still be overkill, but I'd rather do it now, than find out 100 amp won't cut it later.
 
#4 ·
You don't need a ground rod at the garage, if that's what you mean. But, the safest thing is to have a grounding conductor on the circuit feeding the garage, as well as GFCI protection for the receptacles.

Since you're using it for a shop, you might really want to consider installing a subpanel in the garage. Depending on the panel currently installed in the home, you might be able to make room by using twin breakers that take up one slot but are essentially two separate overcurrent devices for two circuits.

Jamiedolan's right, the 14ga wire is not a problem for a 15amp circuit. But, since you've got shop tools it would be nice to have a couple 20amp GFCI circuits for them.
 
#6 ·
Well, right now the whole garage is on a single 14-2. and there is no ground at the garage, just going back through the panel in the house.

Is the 14-2 actually without a ground wire? So there is no bare copper wire in the 14-2 cable?

Currently, I have two 4' 2 bulb t12 shop lights, a garage door opener, and two plugs on that. I added a 150W halogen motion light and 2 more plugs for additional lights, which are getting added. With just the shop lights on, and my miter saw plugged in, the light dim to almost out when I turn the saw on, then come back up, but not 100%. From a safety stand point, this is not good.

I am not trying to talk about out of adding a sub panel. It is a good idea for your tools. However, I just want to mention, what your seeing with that saw is pretty normal and can happen with just 1 light on a circuit that your using the saw on. There really is no safey issue with what your seeing. Motors draw huge inrush currents when they start, normally around 6X the name plate rating, this means a chop saw can draw 90Amp on start up, and will can draw enough to easily cause sufficient voltage drop to dim the lights.

A dedicated circuit for the saw is the best solution to the lights dimming. A larger 20A circuit that has lights on it might help a little bit. Again - No safety issue, unless something is setup incorrectly (i.e. wrong breaker size for wire).


I also have an air compressor, and several other saws I would like to have plugged in so I can use them for my projects. I also plan on having a computer out there, and installing 3 more exterior light fixtures. There is also the possibility of 220V for a welder and/or air compressor.

If it were just lights, there would be no issue.

All good reasons to put in a sub panel. I agree a 40A sub panel would be great, unless your getting a monster welder or a monster compressor. Most welders I've seen and used are 30A or smaller, same with compressors. And you would likely be fine with the 40A with one of those.

As for the 200 amp panel, I was only originally thinking of a 150 amp panel, but was told it's essentially the same cost here to do 200 amp. I have used up all my circuit spaces in my current panel, and have several circuits that are overloaded (thanks to being an old house) I plan on re-assigning

What do you mean by overloaded? Are they tripping the breakers?

some of these circuits, so the extra space will be helpful as well. Sure 200 amp may still be overkill, but I'd rather do it now, than find out 100 amp won't cut it later.

Unless you have lots of high draw appliances, what you need is a simple sub panel setup and not a service upgrade. Tell me what your high draw appliances are; do you have: electric range / oven, electric water heater, electric dryer, heat pump, electric steam generator, electric spa / hot tub, Central AC, Electrical Central Heating, etc?

100 Amp service will power a heck of a lot of stuff. I tried really hard to load down my service for testing purposes. I ran every appliance, plugged in 2 1200 watt heat guns, pizza oven, electric heater, dishwasher, washing machine, toaster, every light on, etc. and could not draw more than about 70amps per leg of the panel (70% of my service used). I do have a gas hot water heater and gas dryer.

Jamie


 
#7 ·
Ok, to answer.

The 14-2 is grounded to the house, but no separate ground.

The safety issue for me is that the light go dim when I am trying to cut, not necessarily a voltage issue. Also, my jig saw doesn't seem to be operating well when I tried to use it.

I wouldn't be adversed to do a 40 amp sub panel in the garage, but would need to know what materials I would need to do this.

As for the house, I do have one breaker I trip regularly, which as far as I have concluded is half the basement, the diningroom and part of the livingroom, and 2 bedrooms on it. I am working on determining how to break that circuit up at the moment, as I am tracing the,

As for the high draw appliances, I have several computers that I run for working at home, and am looking at getting a test system from work that requires a dedicated circuit.

I believe my existing 100 amp panel has 20 spaces, but 2 state do not use. Is there a 100 amp panel that would have more than that? Or how would I go about putting in a sub-panel, and/or the subpanel feed to the garage? I currently have 1 breaker for the garage, one dedicated basement breaker (only 2 plugs on it) and a 220V from a dryer outlet that all could be used for those two tasks. I plan on re-wiring the 3 bedrooms into 3 circuits (1 lights, 1 outlets, and one computer) and I plan on re-wiring the basement, and seperating the livingroom/diningroom lights and plugs. The kitchen and bathroom have already been re-wired and should be ok.

I think that covers it. If I can get by with doing just the 40 amp subpanel for atleast the garage, then that'd be great. I'll probably up the wiring to the garage to handle more (60-100) just incase I have a need to go higher as it will have to be buried.

Thanks for the help so far.
 
#8 ·
You mentioned you have 1/2" conduit to the garage, what kind of conduit is this? PVC? Is it definitely 1/2"? Does this run all the way from the panel to the garage or does it just run from the inside of the house to the garage?

Most computer draw a couple amps at the most. My laptop uses way less than 1 amp. Computers are not high draw unless you have some huge gaming system that has had the power supply change out to a much larger one.

Having a separate circuit will help the lights dimming.

Are your stove / dryer / hot water heater gas or electric? ( I assume the dryer is gas)

You can install up to a 42 position sub panel.

I have to run, but can give you more detailed answers later on.

Jamie
 
#9 ·
it is 1/2", and I believe PVC. It actually is only about 2 inches above the ground. It doesn't actually enter the house. The 14-2 wire comes out under the siding, and down the foundation, then enters the Conduit at ground level, and then comes out at about the same distance on the garage sides, and then into a hole in the siding.

The computer systems are upgraded due to my job. but like you said, should be fine on their own circuit.

All appliances are gas. Fridge and dishwasher are electric. No disposal.
 
#11 ·
In terms of load, no question 100A is good for you now and future expansion. :thumbsup:


You will have the choice to either run direct burial style Romex cable or to run conduit. PVC conduit is easy and cheap. Conduit does allow you to easily change out wires as necessary without digging, but is more work to install.

Your working on 2 separate issues here. 2 sub panels. One for the house and one for the garage. We probably should deal with the house first since you will need some breaker space for the sub panels.

Let me tell you what I did in my home, sounds like you will be able to do just about the same thing.

I have a new Cuttler Hammer CH 42 position panel. This is the panel I have: http://cgi.ebay.com/Cutler-Hammer-C...-Breakers_W0QQitemZ330276476178QQcmdZViewItem

I did not buy it off ebay, that was just the first page I could find with the panel I have. I bought my panel retail from Menards (big box store in the midwest) for $140.

This panel would give you 42 spaces. The 200amp rating is fine as long as you use it as a sub panel. The breaker you use in your main panel is what protects this panel - determins the maxium amperage you can use. You can use any size breaker you want in your current panel to feed this one, as long as you use the correct wire size. You do not need to use a panel this large by any means. I was just showing you what I used and letting you know it works just fine. I have 100a service and this panel is fed off of lugs in my main panel that are protected by the 100a breaker. I used #2 THHN wire from my main panel to this new panel. I ran 1.5" electrical rated (UL listed) grey PVC from the main panel to this new panel. I ran 2 hots to the new panel, and 1 neutral, all #2 wire. (Wire this size and larger is available at Home Depot by the foot). Wire this size and larger is not available in different colors, so for the white (neutral), I re-colored it with white electrical tape. For the ground connection, I used a green #6 ground wire from my main panel to the new sub panel.
When you install a sub panel, you must (this is for your garage or house) keep all of the ground and neutral connections seperated. This cutler hammer panel for example have a seperate grounding bar and neutral bar. There is a bonding clamp that connects the neutral bar to the panel box. You need to remove this when using it as a sub panel. All of the connections that you make in the sub panel will need to have the ground and neutral wires connected to seperate bars in the panel.

Do you have a photo of the inside of your current panel..... I just saw you posted a new message with more info in it while I was writing this. Let me read and respond to that message.

Jamie
 
#10 ·
I meant to take pictures last night, but didn't have my camera (and would have had to dig it out)

So if I do go the subpanel route, how many spaces will I need in my box to accommodate the sub-panel breaker, and what type of wire will I need to run? I'd like to up-size the wire a bit (to handle say 60V incase I should upgrade in the future) I believe I need to look at 6 gauge wire, but should I get 6/3 or individual wires? How many wires will I need to run for this?

Also, for underground conduit, will I need SCH 40 or sch 80 PVC? Does this need to be continued into each structure up to the panel?

Will I need a seperate grounding rod for the garage? Right now I am planning on 4-5 circuits ( 1-2 lights, 2 recepticals, 1 air compressor.) I thought I read that if you are under 6 circuits it isn't necessary.

Lastly, could I run cable and ethernet through the same conduit, or would those be better sent via a second conduit? What size would I need to run the power cables?

Thanks for all the help.
 
#12 ·


That's the best I have for the panel at this moment. I believe that I can get 3-4 spaces freed up in this, as there is the 220V for the dryer that isn't being used, the bottom left 15amp is the current garage, and I think the one above it is a dedicated tool run in the basement, with only 2 plugs on it.

If I can use split breakers in my box, I might be able to circumvent the need for the subpanel, but it might not be the optimal way to go.

I believe the box is a Square D QO box. The bottom right two spaces say do not remove on them, but not sure why.

I believe I would only need to go to a 20 space sub-panel, but assuming I went with the 200 amp, and did later find a need for 200 amp service, would I be able to just switch all my circuits to that panel and use it as my main?

Thanks for all the help so far. I've been trying to read up on all the suggestions you gave me.
 
#14 ·
Some panels have spots that are not to be used. If you can turn the power OFF and remove the cover carefully, and take some photos of the inside of the panel that would be helpful. Also photos around the panel to help determine the placement of the sub panel. You might be able to use tandem breakers to buy yourself an extra few spots. For the cost of tandem breakers, It is cheaper to put in a sub panel if you need more than a breaker or two.

Your question about switching it and using it for 200A service, Yes, I would just buy a panel now with a 200A breaker in it if you think that might happen. That is what I did. I have a old pushmatic panel (used alot in the 1960's) I moved all circuits to the new panel. Right now my old pushmatic panel just supplies service to my new panel, but does not service circuits on it's own. I did it this way, because we will proboly upgrade to 200A service because we are going to put in a hot tub and a electric oven unit.

Jamie
 
#13 ·
I meant to take pictures last night, but didn't have my camera (and would have had to dig it out)
Some pictures would be helpful if you can manage it.

So if I do go the subpanel route, how many spaces will I need in my box to accommodate the sub-panel breaker, and what type of wire will I need to

2 spaces. See my previous post about wire I used. You can you smaller wire if you run the sub panel off of a smaller breaker in your main panel.

run? I'd like to up-size the wire a bit (to handle say 60V incase I should

There is some confusion here. We are talking about a 120V / 240V system here. Nothing is 60V. Maybe you mean 60Amps? If so, then you just need a 60A breaker in your main, and need to run a smaller gage of wire, the gage will depend on what size breaker you end up going with. I did 100A becaue I was moving everything over to this other sub panel, which isn't something your likely to do. However, the cost difference between wire for 60A and 100A service isn't huge when your only talking about running it a few feet.

Some photos of the panel and the area around it would be helpful. There are requirments for clearance around your panel and sub panel, and it photos would be helpful to determin this. Include photos that show what is above and around the panel.

upgrade in the future) I believe I need to look at 6 gauge wire, but should I get 6/3 or individual wires? How many wires will I need to run for this?

3 current carrying wires, plus a ground wire. If you run single strands of wire, you will use THHN wire, and it must be in a conduit. I used 1.5" PVC. It took me about a hour to cut and install the pvc between my 2 panels, and mine are in a corner on 2 seperate walls. If your sub panel can be located very near your main, I would just run single strand as it is very easy to do.

How close can you place your sub panel to your main, any idea? If we are talking about being about to just mount it right next to the main, then I would just use single strand THHN wire in a little 6 inch conduit between the 2 panels.


Also, for underground conduit, will I need SCH 40 or sch 80 PVC? Does this need to be continued into each structure up to the panel?

It can be either, but it needs to be the UL listed conduit for electrical wires. Are you going to be able to run the conduit from your main panel / new sub panel to the new panel in the garage? If so, then you just run single strand in the conduit the enitre distance to the garage. If it is a pain to run the conduit to your panel in the house, then you could use romex / SE style cable, but it still can't be exposed in your basement (needs to go through holes in joists). Conduit can run virtually anywhere. My preferance is to say to give the wires the extra physical protection and run the conduit right to the panel. But I don't know what your physical setup looks like and if it is a huge main to do this or not. The conduit is cheap. 1" is all you need for the garage and it is about $3 for 10 feet.

Will I need a seperate grounding rod for the garage? Right now I am planning on 4-5 circuits ( 1-2 lights, 2 recepticals, 1 air compressor.) I thought I read that if you are under 6 circuits it isn't necessary.

I thought it was required when you ran a sub in a detached garage... But I will need to look this up to find out the exact requirments and if there is an exception.

Lastly, could I run cable and ethernet through the same conduit, or would those be better sent via a second conduit? What size would I need to run the power cables?

They need to be run in a seperate conduit. They can not be mixed. When you have the ground dug up, run another piece of the cheap grey conduit for the ethernet / phone cables.

1" should be more than enough for the garage, it is enough to run #6 for up to 60A to the garage. If you ever think you would need more than that run larger conduit (I can't see why you would ever need more than that unless you think your going to put a hot tub out there.) If that is the case, then I would run 1 - 1/4" conduit.


Thanks for all the help.

Sure, glad to help. Sorry I have been so busy with christmas and all plus my own projects, it's a bit crazy.

Jamie
 
#15 ·
Look like some circuits that are "ungrounded" might be grounded.

That "armored" cable is called bx. If it has a "bonding strip" then you can use the armor/jacket as a ground. You can look at the connectors for a silver tinted thin wire. It usually sticks out of the back of the connector.

I would just swap that panel out with a larger panel.

About the amperage, have a load-calculation done.
 
#16 ·
If the cost of going to 200 amp is not an issue than go for it, who knows what you might be doing in the future. if you plan to run a welder in your garage you should consider 60 amp as a minimum for a sub panel (depending on the welding machine), being as close to the main service as it is it would not be to overly costly to go to 100 amp, then you would be able to have lots of lighting on , be welding something and your compressor can automaticaly turn on without issues. there is no logical reason other than cost to not go bigger than you need, I have seen alot of folks go the minimum then a couple years later regret it. wishing they had done more.
 
#18 ·
Whether you’re rewiring or adding more wiring to an older garage, or running wires in a new garage, you have a decision to make. Do you plan to leave the walls open or close them up with drywall? If you intend to leave the walls and ceiling open, you have to follow the special rules that we show here. The same goes for sheds, workshops or other structures with unfinished walls outside the living space of the house.In a house or a finished garage, electrical cable is protected from damage by permanent wall coverings like drywall, plaster or even wood, but that’s not the case in an unfinished garage. The key to safe, code-compliant exposed wiring is to use the framing members to protect and support the wires. That means not spanning stud or joist spaces with wires. Keep all the cables closely hugging the studs, plates and ceiling joists so they’re not subject to abuse (see “Dangerous Wiring Mistakes,” below).
In this story, we’ll show you a common, cost effective and code-approved way to run exposed electrical cable. But there’s one downside to this method: If you ever do decide to finish the area, you’ll have to completely rewire because the surface-mounted cables will make drywalling impossible.

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#19 ·
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