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cmslick3

join:2004-05-24
Joliet, IL

Garage wiring upgrade

I need to correct/upgrade the service running to my garage sub-panel and I want to make sure I'm doing the right thing.

Background:
House has 100A service which was just upgraded last year. The panel is a Siemens and has plenty of available space in it. There are separate 15 amp breakers running the garage currently. This was a mix up by the electrician who did the work and I didn't catch it... Ugh!
Garage is detached currently being fed by 3 wire buried cable, wrong I know! The main breaker in the sub-panel is 100A I believe.
We have re-wired the garage internally so that's all good to go.

Upgrade:
Install a 60A 220V breaker in the main panel.
Bury PVC conduit 18" below grade from house to garage.
Pull #6 x 4 service wire to garage.
Attach the red and black hot legs to the breaker in main panel, connect neutral and ground to the neutral bus in main panel.
Replace garage sub-panel main with 60A breaker, attach red and black.
Install ground bus & ground rod isolating neutral and ground in the sub-panel.

Questions:
1. Is it necessary to match the 60A breaker rating in the main panel with the main breaker in the sub-panel? In other words to I really need to replace the 100A that's there now?
2. Is the feeder wire size that I've specified sufficient to supply the garage or do I need to go bigger?
3. What else am I missing?


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
Reviews:
·Charter
·voip.ms
First and foremost, it's either 240V or less common 208V. We don't do 220V here.

What's the need for a 60A panel? What is wrong, specifically, with the existing cable? Wrong type? It would be a shame to do a bunch of work for no reason (little gain).

No breaker is necessary in the sub panel, because of the OCP ahead in the main panel. The 100A sub-panel breaker won't hurt anything.

#6 is sufficient if you use the proper type of wire (THWN/TWN). Voltage drop is a concern over distance.
I don't know what the final load will be so I can't comment.
You probably don't need 4 #6, but the overkill won't hurt anything. You might only need 2 #6H, 1 #8N, 1 #8G.

What else are you missing? Expansion risers? Lube?
--
If someone refers to herself / himself as a "guru", they probably aren't.

cmslick3

join:2004-05-24
Joliet, IL
said by nunya:

What's the need for a 60A panel? What is wrong, specifically, with the existing cable? Wrong type? It would be a shame to do a bunch of work for no reason (little gain).

#6 is sufficient if you use the proper type of wire (THWN/TWN). Voltage drop is a concern over distance.
I don't know what the final load will be so I can't comment.
You probably don't need 4 #6, but the overkill won't hurt anything. You might only need 2 #6H, 1 #8N, 1 #8G.

What else are you missing? Expansion risers? Lube?

The 60 amp panel is already there. The need is basically my wife wants to start a lot of woodworking projects and the current setup is tripping the feeder breakers in the basement.
The existing feeder is #10 cable direct buried into the ground only a matter of inches. It also is unprotected leaving the house and coming into the garage, and it doesn't reach the panel in the garage so I had to splice in a short piece to make up for that.

Wire:
»www.homedepot.com/Electrical-Wir ··· ncuQ0WSo

Load:
Table saw, garage door, outlets, space heater, Koi Pond (pump, Aerator), Misc power tools and air compressor.

Good suggestion on the expansion joints, I'll look into them. Cable lube shouldn't be a problem.


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
If you will be running conduit, why are you running UF? THWN would be cheaper and easier to run unless you are just using the conduit where the wire emerges above ground. Conduit needs to be ran typically 18" underground where bare UF 24" IIRC (check local listings)

Do you really need 250'? If it's less, you probably can find the THWN by the foot for less than what that spool will cost you.


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
reply to cmslick3
Why battle with UF cable at $3.18 / ft when you could run THWN at $1.90 / ft (and that's using 4 #6!)?
--
If someone refers to herself / himself as a "guru", they probably aren't.

cmslick3

join:2004-05-24
Joliet, IL

1 edit
I wasn't going to buy the entire roll, at most I need 50 feet. I just thought this would be the easiest way to get the wire through the conduit. From what you guys are suggesting I need to get four 50' lengths of #6 THWN.

Would this suffice:
»www.menards.com/main/electrical/ ··· 6441.htm

I think they have multiple colors, if not I've got colored tape.

what size conduit would i need to run in order to fit four of these wires in to reach the garage?

Edit: Nevermind, Google answered that for me. THHN, #6, 3/4" conduit = 4 conductors.


mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3
reply to cmslick3
I'd call your electrician back and have him fix his screw-up. If you knew it wasn't right, he sure as hell should have known too. Direct-buried only a few inches? Too short to reach the panel? Was he a real electrician?


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
reply to cmslick3
Trust me, you'll kick your own ass if you use 3/4". 1-1/4" minimum. 2" if you plan on forcing UF through it.
--
If someone refers to herself / himself as a "guru", they probably aren't.

cmslick3

join:2004-05-24
Joliet, IL
reply to mattmag
said by mattmag:

I'd call your electrician back and have him fix his screw-up. If you knew it wasn't right, he sure as hell should have known too. Direct-buried only a few inches? Too short to reach the panel? Was he a real electrician?

The only mistake they made was not putting a 240V dual pole breaker in the main house panel which is all they touched. The existing poor garage wiring existed before and they weren't touching that. Sorry if that wan't clear. I can handle purchasing a 15 dollar breaker.

cmslick3

join:2004-05-24
Joliet, IL
reply to nunya
said by nunya:

Trust me, you'll kick your own ass if you use 3/4". 1-1/4" minimum. 2" if you plan on forcing UF through it.

So what cable could you suggest? I have Lowes, Mendards & Home Depot nearby.

Would my last suggestion from Menards work in 3/4" conduit or should I go up to 1"
»www.menards.com/main/electrical/ ··· 6441.htm


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
Reviews:
·Charter
·voip.ms
The wire from menards will work just fine. I would use 1-1/4" conduit for the #6 thwn. I would use 2" conduit for UF cable.

I would also drop a spare conduit for phone / ethernet / intercom (or whatever).

Conduit is cheap, time is valuable, and trenching is expensive.

Code tables can be overly optimistic when it comes to conduit fill tables. While technically code allows you jam X number of wires into a conduit, the reality is that a trade size or two up will make life a lot easier. When using code as a reference, remember it's the "bare minimum" that you can get away with.

You can probably get your materials much cheaper from an electrical supplier. Retail prices on electrical items are a rip-off. We don't have a Menard's here yet (they are still building it). But if their prices are along the same line as Lowe's Depot, then they are probably overpriced too.
--
If someone refers to herself / himself as a "guru", they probably aren't.

cmslick3

join:2004-05-24
Joliet, IL
I found a place at half the per foot price of Menards so good suggestion.

One final question, Does the ground wire need to be #6 or can it be a #8 or #10? The supply shop has black, red and white in #6 but not green.


nunya
LXI 483
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:13
reply to cmslick3
If the feeder breaker is 60A, it can be a #10 copper.

cmslick3

join:2004-05-24
Joliet, IL
Excellent. Thanks again for all your help!!