New 60A Sub-panel for Workshop

5468 Views 8 Replies 3 Participants Last post by theatretch85, Jul 13, 2009

gwoods

Discussion Starter · Jul 13, 2009

I have a garage/workshop located 50’ away from my main 200A service panel. The garage is currently supplied by a 20A circuit which was installed by the previous owner. I will keep this line for the opener and auxiliary power in the garage.

My new home away from home now needs more power. I plan to install a sub-panel that will supply power for (2) table saws (220v), air compressor (220v), dust collector (220v), jointer, various other power tools. It will also power lights and GFCI receptacles. The dust collector (and AC in the summer) is the only thing that’ll be running simultaneously with any single power tool.

I will have a 60A breaker in the main panel to supply the garage sub-panel using 6-6-6-6 THHN/THWN stranded copper through 2” Sch40 PVC for most of the run (I know I could have used #8 or #10 for the ground, but seller gave me a deal for the wire). The trench is 50’ long with the PVC buried 24”. About 12” above grade, I change over to a 2”x 6” RMC nipple and a 2” LB to enter the garage.

The sub-panel in the garage is a Cutler-hammer 125A 12/24 MLO that has a 60A breaker to be backfed with the 2 hots. I also have the hold-down kit for the breaker. The panel WILL NOT be bonded to the neutral bus. I will use some leftover #6 to connect the ground bus, running through EMT, out through an LB to the 5/8” - 8’ EGC using the proper bonding clip. I have the 2-Pole 60A as the disconnect plus 6 circuits on (2) 2-pole 20A breakers, (4) single pole 20A breakers.

My main questions:
1)How does the plan sound thus far? Anything I'm missing??
2)For the entry into the house and into the garage, should I use “LB to nipple to LB to EMT” connection for each entrance or “90 radius bend to LB to EMT?”
3)I’m at (or possibly over) the 6 breaker (6 sweeps of the hand) rule for this box, thus the need for a disconnect. Does the 60A breaker comply as a disconnect, or will I need an AC/Pool type external disconnect?
4)Do I need (2) EGC’s for the garage or does a single EGC suffice? My main panel has an EGC as well.

My apologies for all the questions, just want to be sure things line up properly.

I appreciate the feedback. Thanks!

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theatretch85

· #2 · Jul 13, 2009

Couple things I noticed:

You cannot have 2 feeders to the same structure; just give the garage door opener its own 15 amp circuit in the subpanel, sounds like you should have enough spare spaces. You could even tie it in with some primary lighting (or exterior lights).

The ground rod wire running through conduit must be properly bonded to each end of the conduit, just simply running the wire through the conduit is a no-no. Personally I'd just run it inside the wall and out through the same hole as your LB (just run it right next to it) and then caulk the hole.

I believe to be code compliant you need 2 8' ground rods at your detached structure.

The rule of 6 doesn't apply after you install a disconnect. Code minimum for a disconnect at your detached structure is 60 amps (no matter what the supply is).

How far does your feeder run inside the garage? Does it come in and go directly to the panel within a couple feet? If your feeder runs further than about 5 feet inside the detached structure, you will probably need a separate disconnect outside or nearest the point it enters the building.

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gwoods

Discussion Starter · #3 · Jul 13, 2009

theatretch85 said:
The ground rod wire running through conduit must be properly bonded to each end of the conduit, just simply running the wire through the conduit is a no-no. Personally I'd just run it inside the wall and out through the same hole as your LB (just run it right next to it) and then caulk the hole.

The conduit and wire was to be bonded at both ends. My meter has a wire inside EMT conduit clamped to a grounding rod. My plan was to run the same.

theatretch85 said:
I believe to be code compliant you need 2 8' ground rods at your detached structure.

Is 6ft the required spacing/distance that should exist between the two rods?

theatretch85 said:
How far does your feeder run inside the garage? Does it come in and go directly to the panel within a couple feet? If your feeder runs further than about 5 feet inside the detached structure, you will probably need a separate disconnect outside or nearest the point it enters the building.

The feeder will run 3ft before entering the bottom of the panel. However, the panel is 6ft away from the entrance. Is this an issue?

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theatretch85

· #4 · Jul 13, 2009

gwoods said:
The conduit and wire was to be bonded at both ends. My meter has a wire inside EMT conduit clamped to a grounding rod. My plan was to run the same.

The ground wire has to actually be bonded to the ends of the conduit fitings, not just to the panel and the ground rod itself. just simply running the wire through conduit is not alowed. PVC conduit might be ok, but I know metalic conduit requires a bond at each end of the conduit.

Someone here might be able to elaborate more on this, I am drawing a blank on the reason behind it. Like I said, you might bo ok just sleeving it in PVC.

gwoods said:
Is 6ft the required spacing/distance that should exist between the two rods?

Minimum 6ft between the two rods, yes.

gwoods said:
The feeder will run 3ft before entering the bottom of the panel. However, the panel is 6ft away from the entrance. Is this an issue?

No, that should not be a problem.

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Scuba_Dave

· #5 · Jul 13, 2009

I used a 100a panel & ran my #6 directly to the 100a lugs (I was told?)
As long as they are rated for #6 wire you can use the main lugs & main breaker
The 60a feed breaker in the main panel is the overlimit protection
I hope the wire you are using is rated for burial - wet location? - even conduit under ground is a wet location

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gwoods

Discussion Starter · #6 · Jul 13, 2009

Scuba_Dave, I can understand that setup in an attached bldg. But a detached would need a disconnect of some kind per NEC.

And, yep, the wire is rated THWN, direct burial in wet location.

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Scuba_Dave

· #7 · Jul 13, 2009

The main breaker is still the disconnect (100a) for me
It was not a main lug panel without a main breaker
As I understand it you have a 125a panel with a 125a main breaker (maybe not?)
Ah - I see MLO stands for Main Lug only - so you don't have a main breaker
That explains it

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gwoods

Discussion Starter · #8 · Jul 13, 2009

Scuba_Dave said:
Ah - I see MLO stands for Main Lug only - so you don't have a main breaker
That explains it

Correct

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theatretch85

· #9 · Jul 13, 2009

gwoods said:
Scuba_Dave, I can understand that setup in an attached bldg. But a detached would need a disconnect of some kind per NEC.

And, yep, the wire is rated THWN, direct burial in wet location.

THWN is not direct burial rated, its listed for use in conduit underground or in wet locations, but not by itself. UF is rated for direct burial, but tends to be more of a PITA to change out or troubleshoot later.

So long as the main breaker is rated for a minimum of 60 amps, this satisfies the code requirement for the disconnect at the detached structure.

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