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How to properly ground a garage or shed....

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parkland

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I know this isn't the general kind of question asked here, but I figure it's worth a shot.

We bought an older house, and the house is grounded normally.
At some time, someone ran electrical wires to the garage, which is about 80 ft away.
2 wires, run from the breaker, to the garage roof, no grounding wire.
The wiring in the garage is all wired in for a ground wire, but the main junction box obviously doesn't have one, so nothing is grounded in there.

The 2 old wires looked old, and in fact looking closer, I think someone used old clothes line for wire. The plastic coating is chipped off in several spots, so I decided to run some new wires underground.

I utilised some wire I had sitting around, it's really thick multi strand wire from a solar project a few years ago. 4 conductor, rated 480 volt, and I buried it about 8" deep in 1" electrical conduit.
I know thats not how code says, but I figure it's better than clothesline, and I already had everything to do it, so I went for it.

Right now, the garage with the crap old wires is on a 15 amp 115v breaker, and I have a little welder; and if I run anything at the same time I run the welder, the breaker overloads.
So, I wanted to utilize the 4 wires for 2 115v 15 amp circuits, or maybe even one 115v and one 230 v for a bigger welder.

Either way, should I have ran a 5th wire for a ground to the house box ?
Will I have to sacrifice one of the 4 conducters already buried for a ground?
Can I pound a ground ron in the ground near the garage and use that for a ground?
 
Are you in the United States? The voltages you have suggest that may be the case.

The simple answer is you can run a ground wire of suitable gauge from the house to the garage, or you can install a grounding electrode at the garage and treat the supply from the house as a service. That is, like it is coming from the electric company through a meter. I have done the later for my barn.

The best answer is to go to Lowes or Home Depot and check out "Wiring Simplified" current edition. That soft cover book covers NEC codes. You need Chapter 8 for the service description or Chapter 10, page 119 of the 2002 (old) version. I can't put my hands on the newest version right now.

Public libraries also have the guide available. The cost is about $12 USD and is money well spent.

John
 
Sorry, What I meant was "How to safely ground", not "how to ground by code" .

If this garage ever burned down, there are a million reasons insurance would never cover it.
It is sort of a mad scientist type place, alternative fuels are in here sometimes, experimental
combustion experiments, and oodles of other things happen here that I'm sure are illegal.

Thank you very much, I saw some copper plated ground rods the other day, I'll pound one of those in several feet and run off that. :D
 
Code is safe and in the vast majority of cases completely reasonable and logical to those who understand. Anything else is in your imagination based on incomplete knowledge.

Why ask, if you don't want to listen to the answer. I said nothing about insurance.

John
 
Sorry, I do take value in you're advice, but not everything here is built to code. I am trying to get it better than it is now.
I just was looking at things, and the ground wire from the garage is actually connected to one of the hot wires coming from the house.

I'm typing this on a computer plugged into that power, I'm surprised it works with the ground having power on it instead of being grounded or unhooked.
 
For all electrical runs outside the house, I run either an 8' ground rod at the electrical entrance to the shed or a ground fault plug at where it leaves the house.
Like John said, the little books from Home Depot are money well spent.
 
Since you already have a 4 conductor line going out there you already have all the lines required to meet code plus being buried in a conduit its likely going to stand up to basic inspection scrutiny as well.

For a two circuit four wire system you use two lines for your 120/240 split with the third line as their common and the fourth line as the ground.
At 80 feet+ from your main service and being its own building it would be highly recommended to have an additional ground rod installed as well.

At 80 feet how much power you can pull is still going to fall in to the normal ratings for what ever size cable you used within reason.

Here is a good place to start.

http://www.armstrongssupply.com/wire_chart.htm
 
You never said how big the conductors are (wire size) for one.

since this service is considered "Detached", it requires it's own ground rod. L1, L2, and Neutral should connect to the box. No ground from the house. Ground should go to a ground rod at the garage.
 
Thanks everyone,

House wiring isn't something I've ever done. I do lots of solar system work, but you get used to the same things all the time, and this is new and just unfamiliar.
I can't remember the wire guage, but it is wire for running water pumps that go down a well, so it is pretty thick, and intended to run 3 HP electric pumps quite
a distance from a home, so I suspect it should do well.
 
Most likely that would be 12 gauge or at most 10 gauge copper wire. Submersible pump cable has a very thick plastic on it which makes it look far bigger than it actually is.

As far as having the 4th wire as a earth ground going back to the house there is no rule in the code books that say you cant have it as a secondary common/grounding backup. ;)

Still use the ground rod at the garage though. ;)
 
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