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Old 08-25-2008, 03:13 PM   #1
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Wiring garage workshop


Hi,
I will be running new feed from my house to my detached garage. Total run is approx 100ft. My main service is 100 amp and I plan to have a 60 amp breaker feeding a sub panel in the garage.
Is it correct to run #6 guage wire for this?

I was going to run 6/3 copper wire inside of 1 inch PVC conduit along the side of the house and then bury it from the end of the house to the garage.
6/3 copper is expensive here, so I got a quote on 4 seperate feed lines, all #6 copper, (2 hots, a neutral and a ground).

Does it matter? Is one method better than the other?

Aside from having the ground wire green, Does it matter what colour the feed wires are? I like 6/3 'cause you get black,red,white & green.

Loads in the garage will be lighting, woodworking equipment - mostly 15 & 20 amp stuff, table saw, dust collecter and one 220v jointer. It's a single user set-up.
This 60amp service should be fine with room for some expansion like a heater.
Any comments are appreciated. ~Cheers.

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Old 08-25-2008, 03:35 PM   #2
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Try this http://www.southwire.com/voltagedropcalculator.jsp

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Old 08-25-2008, 05:18 PM   #3
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Pull individual conductors, THWN

In the US, the neutral must be white (no marking tape...lame)

The ground can be # 10 green (no marking tape....lame)

The hot legs can both be black or any color other than white/green.

You would need a ground rod w/ #6 to the sub.

Keep neutrals/grounds separated (isolate the neutral bus)
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Old 08-25-2008, 10:38 PM   #4
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To add to what 220/221 said, if you are using R90 you will have to bump up the ground to a #8.

My understanding of the codes is that in your sitution you do not need a ground rod, your ground you pull in will be good.

Maybe another Canadian can jump in and confirm or tell me that I am wrong.
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Old 08-26-2008, 11:17 AM   #5
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OK - cool thanks.
Is it usually the case that the green/ground wire is higher guage (smaller wire) that the feed wires?

I was told that I need to establish a ground, with 2 ground rods or a single plate electrode (unless one is there already).
Does this seem right?
As far as I know, there is NO grounding rod or plate at the garage.
~Cheers
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Old 08-26-2008, 11:22 AM   #6
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I'm a bit surprised that the ground wire is allowed to be smaller than the feed wires.
Is this only if a ground rod (with the proper size wire for the capacity) is used?

FW
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Old 08-26-2008, 01:36 PM   #7
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Quote:
Originally Posted by fw2007 View Post
I'm a bit surprised that the ground wire is allowed to be smaller than the feed wires.
Is this only if a ground rod (with the proper size wire for the capacity) is used?

FW
No. Ground wires are used only for fault current, so by that nature they are allowed to be smaller.
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Old 08-26-2008, 02:32 PM   #8
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Quote:
Pull individual conductors, THWN

In the US, the neutral must be white (no marking tape...lame)

The ground can be # 10 green (no marking tape....lame)

The hot legs can both be black or any color other than white/green.

You would need a ground rod w/ #6 to the sub.

Keep neutrals/grounds separated (isolate the neutral bus)
As 220/221 posted, in the USA this would be the compliant method. It is not recommended to pull 3 conductor with ground cable thru conduit. You are going to find this to be difficult and results in a larger conduit than is necessary. Use individual conducters that are wet location rated and in compliance with your Canadian codes.

Your running a 4 wire feeder from your homes main panel to the detached garage. This feeder is protected by a 60 amp breaker. The equipment ground is calculated by the size of the overcurrent protection. In this case in the USA the size minimum is #10 copper for 60 amps.

The ground rods at the garage are mandatory here and in Canada. These have nothing to do with the equipment ground in the feeder. The equipment ground in the feeder does not determine whether you need a ground rod or not. The two have nothing to do with each other.

So yes you need an approved grounding electrode(s) at the detached garage.

I don't know how you "bump up the ground" in cable without increasing cable size. However it is possible Darren was considering the sub in the garage to be 100 amps with 100 amp protection at the house panel, in this case #8 copper would be required. It is also possible that Canada requires #8 for a 60 amp feeder, though this doesn't make much sense if you consider the available fault current. Also R90 would not be allowed in a conduit underground...it is not wet rated. So I am assuming you mean your considering something like RW90. However it cannot be direct buried if memory serves me correctly.
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Old 08-26-2008, 04:10 PM   #9
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Quote:
Is it usually the case that the green/ground wire is higher guage (smaller wire) that the feed wires?
Larger than 20 amp, yes

30-60 amps require a 10 ground.

200 amps (3/0 or 4/0 feeders) require a #6 ground.

That's I can remember. I have to look everything else up.
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Old 08-26-2008, 04:37 PM   #10
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Quote:
Originally Posted by Stubbie View Post
The equipment ground is calculated by the size of the overcurrent protection
In Canada your bonding cable and ground cable are sized according to the ampacity of the largest ungrounded conductor.

So in your example if you took the #6 and put it on a 20A breaker you still need a #10 ground. If you put it on a 60A breaker you still need a #10 ground.

When I said my understanding of the code is that you don't need a ground rod at the shed is the following. I could be interperting this wrong as well.

CEC 10-208 Grounding conections for two or more buildings or structures supplied from a single source
Where two or more buildings or structures are supplied from a single service.
a-the grounded circuit conductor at each of the buildings shall be connected to a grounding electrode and bonded to the non current carrying metal parts of the electrical equipment OR

b-expect for buidings houseing livestock, the non current carrying metal parts of the electrical equipment in or on the building shall be permitted to be bonded to ground by a bonding conductor run with the feeder or branch circuit conductors.
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Old 08-28-2008, 12:04 PM   #11
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The more I learn - the more I realize I don't know.

RE: cable to be buried;
Is RW90 the same as THWN ?
Because I thought THWN is an individual wire rated for wet locations.

In any case I'll be using cable rated for wet locations in conduit. I don't mind going 1 size conduit larger to make the pulling easier. the added cost is worth the convenience.
~Cheers

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