Looking for advise on setting up a sub panel


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Old 04-26-19, 07:47 PM
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Looking for advise on setting up a sub panel

I want to put a sub panel into a detached workshop that I have. I will need to run about 75ft of cable (about 50 buried outside). Off of the sub panel I want a 240v 20amp outlet and a 120v 20amp outlet.

In theory a 40 amp sub panel would work but I cant seem to find one with 3 or more slots for breakers (2 for the 240v and 1 one for the 120v).

of course I could put a 60amp sub panel and have lots of slots but then because of the distance I would need to run 4/3 cable? But the only 4/3 cable I can seem to find is industrial armored cable at like $20 a foot.

If anyone has some advised on how to achieve this without thousands of dollars in cable I would REALLY appreciate it.

Also I would only be doing the grunt work and I would have a real electrician inspect my work and make the final connection.

thanks for your time.
 
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Old 04-26-19, 08:04 PM
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You could put in a 60 amp sub panel and still feed it with a 40 amp breaker.
 
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Old 04-26-19, 09:01 PM
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The 60A panel just means its maximum. Like joed mentioned you don't need to feed it with 60A. Are you looking for underground cable or are you going to use PVC ? I'm a PVC man on any underground circuit over 20A.
 
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Old 04-27-19, 04:36 AM
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I have been thinking about whether or not to put a conduit. Other then reduced risk of physical damage is there a reason to use conduit? I live in southern Ontario so the ground does freeze if that makes a difference.
 
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Old 04-27-19, 07:05 AM
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Use 6/3 UF-b direct bury if you don't want to mess with conduit underground. It should cost less than $4 US by the foot. That will give you 50A.
 
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Old 04-27-19, 07:34 AM
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Other then reduced risk of physical damage is there a reason to use conduit?
Protection is one reason, another is if you upsize the conduit it a bit, it's easy to upgrade the feed in the future.

I had a single 20A circuit to my detached garage installed however many years ago. I was able to easily upgrade to a 30A @ 240v just by pulling new wire and adding a subpanel since the original installer used 3/4" conduit. No digging or anything. It was glorious!
 
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Old 04-27-19, 09:40 AM
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One more question for you guys that have been so helpful! Do I need to put a separate ground rod into the ground or can I have the sub panels ground attached to the main panels ground?
 
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Old 04-27-19, 09:51 AM
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The subpanel (more exactly the first panel) in the detached garage needs its own ground rods. And also a ground wire with the two hots and neutral coming from the main house.

A #10 gauge ground wire goes with #6 or #8 gauge feed conductors in conduit also.
 
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Old 04-27-19, 09:51 AM
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The subpanel needs at least one ground rod. That provides your GEC (Ground Electrode Conductor) for limiting atmospheric charges,

can I have the sub panels ground attached to the main panels ground?
Different ground, different purpose. That is your EGC to clear faults to metal parts.

Both the GEC and EGC are needed.
 
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Old 04-27-19, 09:58 AM
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Not in Canada. You do not need ground rods. A connection to the main panel ground is all you need.
From the Ontario ESASAFE FAQ pages

Question
I have a small building in which I wish to have a sub service installed. The sub service will be fed from my house. Do I need to have separate ground rods or a plate installed at the sub service?
Answer
It depends. The Code provides two options;
First, the sub service shall be grounded by connection to a ground electrode; or
Second, the sub service shall be bonded back to the main service with a bonding conductor run with the feeder conductors.
Note that buildings housing livestock are required by the Code to use the second option.

Rule 10-208.

Ontario Electrical Safety Code 26th Edition/2015
 
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Old 04-29-19, 05:40 AM
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If you have rocky soil conduit is a good idea because the rocks shift around during freeze/thaw cycles and can cut the cable. It also allows a burial depth of 18" instead of the 24" for UF cable.
 
 

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