Garage/workshop wiring

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  #1  
Old 05-07-12, 07:52 PM
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Garage/workshop wiring

I am currently in the process of converting a carport to a closed in garage. I have pretty good knowledge of wiring in the lights and the outlets as well as running the wire. I have never wired in a breaker box before, have added new circuits though.

I currently have a 100 amp breaker box inside my house so I do not believe that I can just add a sub panel as I'm pretty much full up on breakers. So what my thought is, install a completely separate panel to the garage. On my meter pedestal, there is currently two separate breakers, one that is 100 amp and runs to the house, and another that is 50 amps that used to run to a hot tub. I no longer have the hot tub and was just going to use that breaker and wire to run to the new breaker box in the garage. First off, is this even legal to do and up to code? Second, would this wire that ran to the hot tub be large enough to run to the garage, i am not sure on what gauge the wire is( it have four wires total, red, black, white, and ground) the distance the wire will run is maybe 10 or 15 feet from the meter to the garage?

I do not plan on running mulitple large tools at the same, largest thing I would think that I would run would be an air compressor, or maybe a welder.
 
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  #2  
Old 05-07-12, 08:22 PM
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I should add, I will be having two sets of 4 foot, T-8 shop lights, on one 15 amp breaker, then I will have 4 outlets on another 15 amp breaker, and then have two outlets on another 15 amp breaker. is that going to be too much, obviously i wont be using all outlets at the same time, only continually running thing will be a upright freezer.
 
  #3  
Old 05-07-12, 08:32 PM
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If you have a circuit breaker panel at your meter then that panel is your service panel and all panels wired after need to be wired as sub-panels. This means four-wire feeders between the service panel and the sub-panels with the neutral bus in the sub-panel isolated from the enclosure and an equipment grounding bus installed and bonded to the enclosure. You also need at least one eight-foot long ground rod driven as near to the sub-panel as practicable and connected to the equipment grounding bus with no #6 copper wire, either green insulated or bare.

Fifty amperes at 240/120 volts is 12,000 watts and that should be more than ample for your shop. Without knowing the conductor size or the cable construction I cannot say if the hot tub cable could be used for the feeder.
 
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Old 05-07-12, 09:36 PM
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A separate grounding electrode at the subpanel?
 
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Old 05-08-12, 12:17 AM
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Yes. Sub-panels in buildings separate from the service panel require grounding rods/electrodes. Since the service panel is on a pedestal all the sub-panels are in separate buildings and require ground rods.
 
  #6  
Old 05-08-12, 05:33 AM
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The panel inside the house is ground to the frame of my trailer(14x80 mobile home). The hot tub is grounded back to the meter pedestal. Will this not work for the ground for the new panel in the garage?
 
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Old 05-08-12, 05:44 AM
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A 15 amp circuit might not be enough for an air compressor or welder. Any special reason you're using 15 amp instead of 20?
 
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Old 05-08-12, 06:41 AM
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For the shop receptacles I would run #12 on a 20 amp breaker. More capacity to run larger items.
 
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Old 05-08-12, 07:49 AM
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Got it. I'd missed that the service entrance was on a pedestal.
 
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Old 05-08-12, 07:52 AM
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Will this not work for the ground for the new panel in the garage?
Your confusing earth ground and equipment ground. You need both. The former for atmospheric electrical buildups and the latter a low impedance back to the source in case of an electrical fault not cleared by the neutral.
 
  #11  
Old 05-08-12, 10:24 AM
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Okay now I understand what you mean on the ground. So how do I wire that in then? Obviously black and red to the main in the garage and the white to the neutral bar and ground to the ground bar. Where do I run the ground from the ground rod to?
The box I have is a 100 amp breaker box... am I going to need to buy a new one or can I use this one?

And as far as the air compressor goes, its only a small 6 gallon compressor. I've ran it off the outlets in my house with no problem and they are only 15 amp outlets
 
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Old 05-08-12, 11:36 AM
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50Amp with a number of 15amp plugs should be good enough for a small garage.
I ran my garage (at the old house) on a 60amp feed which ran my compressor, stereo (nothing huge) and a number of hand power tools with no issues. I even had a 5500W fan forced electric heater and was far from any issues.

I would suggest running a plug on one or both sides of the bay door (provided you have room and local codes). This is extremely handy.
 
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Old 05-08-12, 12:26 PM
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The box I have is a 100 amp breaker box... am I going to need to buy a new one or can I use this one?
What "box"? Do you mean the circuit breaker panel you want to install in the shop?

You need a local disconnect in the shop circuit breaker panel. The easiest way to do this is to use a circuit breaker panel that has a main circuit breaker. The rating of this main CB is not important but you need it to be at least equal to the CB in the service panel on your meter pedestal.

If the panel you have is of a known deficient manufacturer such as Zinsco or Federal Pacific I strongly urge you to buy a new panel.

Where do I run the ground from the ground rod to?
The Grounding Electrode Conductor (GEC), the wire that runs from the ground rod to the panel connects to the equipment grounding bus in the panel.
 
  #14  
Old 05-09-12, 09:09 PM
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The breaker panel that I have to put into my garage is the old one that came out of my house, it is a GE breaker panel and has a main 100 amp circuit breaker on it. I just want to make sure that will be okay to use with only a 50 amp breaker on the meter pedestal.

I double checked the wires that I have and they appear to me to be 6 gauge wires, don't have an actual wire gauge guide to tell the size. I pulled the cover off of the meter pedestal and it is actually not grounded at all, the ground is just hanging in the meter pedestal. I am assuming that that is no big deal and that I would still have to put in a ground rod. where is live it is almost going to be darn near impossible to bury a full 6 foot rod in the ground (lots of shelf rock) if I cannot bury it the full 6 feet what do I need to do?

This wire was never run in conduit even to the hot tub, do I have to run it in conduit to the breaker panel in the garage?
 
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Old 05-09-12, 09:29 PM
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I pulled the cover off of the meter pedestal and it is actually not grounded at all, the ground is just hanging in the meter pedestal. I am assuming that that is no big deal
Big deal. It must be connected.

where is live it is almost going to be darn near impossible to bury a full 6 foot rod in t
Eight feet not six feet. You could drive it at 45° or bury it horizontal.

This wire was never run in conduit even to the hot tub, do I have to run it in conduit to the breaker panel in the garage?
Is it really wire or is it cable. If it is direct burial cable it can be buried without conduit.

The breaker panel that I have to put into my garage is the old one that came out of my house, it is a GE breaker panel and has a main 100 amp circuit breaker on it. I just want to make sure that will be okay to use with only a 50 amp breaker on the meter pedestal.
Yes. It is common practice. The 100 amp main breaker serves only as a disconnect so size isn't important as long as it is equal to or larger then the supplying breaker.
 

Last edited by ray2047; 05-09-12 at 11:36 PM.
  #16  
Old 05-09-12, 10:50 PM
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I haven’t been fully following the thread. But to add to what ray said.The electrode shall be installed such that at least eight feet of length is in contact with the soil. It shall be driven to a depth of not less than 8 feet unless rock bottom is encountered, the electrode shall be driven at an oblique angle not to exceed 45 degrees from the vertical or, where rock bottom is encountered at an angle up to 45 degrees, the electrode shall be permitted to be buried in a trench that is at least 2.5 feet deep. The upper end of the electrode shall be flush with or below ground level unless the aboveground end and the grounding electrode conductor attachment are protected against physical damage. You shall also use listed direct burial ground clamps.
 
  #17  
Old 05-10-12, 01:57 PM
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Where does the ground in the pedestal need to be connected to?

Is there any regulations on how far the ground rod must be from the breaker box? And any regulations on the gauge of wire used to clamp to it?

The wires that ran to the hot tub at bundled together in a black casing. There are no markings on it to indicate what kind it is. When I bought the house it was just laying on top of the ground and ran up to the hot tub which was on the deck directly above the meter pedestal.
 
  #18  
Old 05-10-12, 02:49 PM
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The grounding electrode conductor (GEC) at the meter/service panel needs to be connected to a ground rod as previously described. The gauge of wire is dictated by the the size of the service conductors but generally #6 copper is acceptable for residential installations. This wire MUST be copper. The grounding electrode (ground rod) should be a close to the service as is practicable. Do you have a metallic water pipe anywhere near the electrical?

Look very closely at the cable for the hot tub, including turning it all around. The marking may only be embossed into the covering but they should be there every two feet.
 
  #19  
Old 05-10-12, 03:28 PM
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There is an outdoor water spigot (frost free 2 foot bury) located within two feet of the the meter pedestal. Why?

So I know that I've gone back and forth asking the same questions over and over. But do i need to have two separate grounding rods for this application? Or do I just need one?
 
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Old 05-10-12, 03:41 PM
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Your power company may not allow any grounding connections to be made in the meter socket. The socket should be sealed so that unqualified persons do not have access to unfused live power.
 
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Old 05-10-12, 04:12 PM
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Is your meter pedestal the kind they install for a mobile home underground service?
 
  #22  
Old 05-10-12, 04:58 PM
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I think it is about time for some pictures.

Sometimes the grounding electrode conductor comes from the meter but more often it comes from the service panel where it connects to the neutral bus which is also bonded to the panel enclosure. As I understand this installation the meter and the service panel are adjacent to each other, either meter above or side-by-side.

If your water hydrant is connected to a metallic piping system that has a minimum of 10 feet buried then that would be the primary grounding point and any rods would be secondary.

Picture of the pedestal showing both the meter and the service panel and a picture of the inside of the service panel with the cover over the circuit breakers removed should clear up any misunderstanding.
 
  #23  
Old 05-10-12, 09:07 PM
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meter pedestal, black bundle of wires is for the new garage panel, water spigot next to it.

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front of panel open, breaker on right is 200 amp for the house, breaker on left of for the garage (50 amp)
sticker on front of panel says "each handle in this box is a service disconnect"
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tried to label, cant really see it though, left is 50 amp for garage, right is 200 amp for house. Down in the bottom left corner you can see the ground wire, it is not connected to anything
 
  #24  
Old 05-10-12, 09:53 PM
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First, do you have a well or are you supplied from a municipal system? Do you know if the supply piping to the yard hydrant is metal (copper or galvanized steel) for at least ten feet?

On to the pictures.

Bad news is that old hot tub cable is most likely type NM and not suitable for either a hot tub or your garage project. Nor is it suitable for use outdoors and most definitely not for burial. Most likely it isn't even a large enough conductor to be used on that 50 ampere circuit breaker. Also, you cannot just run a cable out the knockout that way but MUST use an approved clamp or else conduit.

Semi-bad news is that is a Ground Fault Circuit Interrupter (GFCI) circuit breaker, which is required for a hot tub but could be subject to nuisance tripping when used as the main circuit breaker for your garage.

Neither good or bad is that the "ground" wire your are referencing is not the Grounding Electrode Conductor (GEC) that most of us were thinking but merely the equipment ground to the (former) hot tub. Normally it would have been connected to the neutral/equipment ground buss (between the two circuit breakers) but it may have been disconnected because it caused nuisance tripping of the GFCI circuit breaker due to the wrong cable being used.

Good news is that on the neutral bus you have the incoming neutral conductor at the top and then a heavy bare copper that appears to exit through the back of the enclosure. This bare copper would be the GEC and most likely goes through the back of the pedestal to a ground rod (or two) and also the water pipe providing it is a metal pipe at least ten feet long.

Bottom line. You need to run conduit from the panel to a minimum of 24 inches deep and with a ninety degree bend pointing towards the garage. At this point you may either use type UF cable of no less than #6 gauge and having three insulated plus one bare conductor to the garage and use a similar piece of conduit from the ground up into the garage panel. The conduit is to protect the cable from physical damage where it enters/leaves the ground.

OR, you may use a service entrance direct burial cable in the same manner.

OR, you may run conduit the entire distance and use four individual conductors of type THWN wire through the conduit. My preference is this last method.
 
  #25  
Old 05-11-12, 07:29 AM
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First, do you have a well or are you supplied from a municipal system? Do you know if the supply piping to the yard hydrant is metal (copper or galvanized steel) for at least ten feet?
No I do not know for sure on this, I am on a well system though



I looked at the box again, on the neutral bar, there is the wire coming out of the top of it and then there is a soild piece of copper a little bit below that( the one you referenced I believe). This cable does not exit the box but is screw to the box just above it.

I am starting to think that maybe im getting a little over my head with this, and to be safe I would be better off just calling an electrician to come wire it up. Im just afraid of how much it is going to end up costing to have someone do this
 
  #26  
Old 05-11-12, 11:26 AM
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I think bringing in a competent electrician is a good idea. He (or she) can determine if the service is properly grounded and give you area-specific code information for your project. The electrician may be willing to work with you on your project having you do the digging for the cable or conduit between the pedestal and the garage.
 
  #27  
Old 05-11-12, 11:34 AM
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I agree with Furd!!!
 
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Old 05-11-12, 11:52 AM
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Upon reviewing this entire thread, especially the pictures, I think it is imperative to get a competent electrician to look over the service equipment. The conductors coming out of the 200 ampere circuit breaker look might small to me, especially when compared to the incoming conductors.
 
  #29  
Old 05-12-12, 08:35 AM
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The only reason I can cite for the wires being smaller coming out is the fact that inside my house is only a 100 amp breaker panel, with a 100 amp main. I have already had one electrician come out and look at it when we first bought the place to discuss switching to a 200 amp breaker panel in the house and he looked at it and didnt say anything about it not being safe.

Digging the conduit is going to be tough at there is about a foot wide area that is covered by a deck walkway. Like I said I think this is beyond my abilities, and I would rather be safe then sorry, good news though, my next door neighbor is an electrician!!

Thank you all for your help and input. I will post up in this thread when all is said and done and let you all know what I had to do to run this new panel.
 
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Old 05-13-12, 07:25 AM
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The only reason I can cite for the wires being smaller coming out is the fact that inside my house is only a 100 amp breaker panel, with a 100 amp main. I have already had one electrician come out and look at it when we first bought the place to discuss switching to a 200 amp breaker panel in the house and he looked at it and didnt say anything about it not being safe.
Note that Furd suggested a competent electrician. Yes, the load side wires are much smaller than the line side wires. That 200 amp breaker should be changed to meet the rated ampacity of the load side wires. Presently. you do not have adequate protection on the underground feeder to house or trailer.
 
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