Garage Subpanel - Check My Plans, Please?
Hi guys, would you please let me know if you see any obvious problems in my plans here?
The project is to put a 60A subpanel in my detached garage.
- Garage currently has a single 15A 120V circuit, which I will disconnect.
- I want to get 60A for 120V and 240V circuits. Loads in the garage will be lights, garage door, and one power tool at a time, the largest being a 240V 9A table saw.
- The garage is detached, separated from the the nearest exterior wall of the house by a 4 foot wide breezeway. That happens to be the house wall that the electric meter is on. House and garage are wood frame.
- The breezeway between garage and house is concrete, running cable underground will be hard. So I would like to go overhead. The garage eave is 8 feet above ground.
- The main panel is 125A, located in the unfinished basement, directly below the meter location. It has four slots unused, so I can fit a 240V breaker.
Basically, I believe I need to:
- Add 240V 60A breaker to main panel, to feed subpanel.
- Use four THHN wires (#4 black/hot, #4 black/hot, #4 white/neutral, #6 bare/ground). In the main panel, hot wires to the breaker, neutral wire to the neutral bar, ground wire to the ground bar.
- Connect PVC conduit to top of main panel with coupler/locknut. Run conduit up the wall, exit house, run conduit up exterior of house to a level just below the garage eave. Is schedule 80 PVC conduit, 1.5 inch okay? Total length of the run from main panel to subpanel will be about 40 feet, including all the bends.
- Connect house to garage with a boxed horizontal wood member, 8 feet above the ground - I'll call it a "header". I'll put a gate under that header, so that it looks like there is a reason for it to be there, I'd like to gate off that walkway anyway. I've asked electrical inspector if there's a problem connecting the two structures in that way - we'll see if I get an answer.
- Run conduit inside header, where it is concealed and protected. Can I use 90-degree access fittings to make the bend from exterior/vertical to in-header/horizontal - easier to conceal than a standard 90-degree bend - or is that a water intrusion point? This will put the conduit 8 feet above the ground. Is there a minimum height, code or common sense, for overhead electrical in a conduit/attached to structure? I know there are requirements for overhead spans of hanging cable, but don't know if these apply to conduit.
- Inside garage, install panel with a ground bar. Any suggestions on type/model? Main panel is a Square D, I was going to use the same type for the subpanel. Chosen wall location has 30 inches horizontal clearance, and 3 feet clear space in front. Any other location requirements?
- If city requires - I've asked inspector, waiting on his answer - drive ground rods into the ground by the garage. One or two rods? Copper bonded, 8 feet, with bolt-type connector? Connect rod to ground bar in subpanel.
- Inside the subpanel, make sure neutral and ground bars are not bonded. Install 60A main breaker. Hot wires to the main breaker, neutral to the unbonded neutral bar, ground to the ground bar. Ground wires from the ground rods, if any, also to the ground bar.
- Disconnect existing circuit to garage.
- Hook up my 240V and 120V circuits normally. The garage interior is finished, so use PVC conduit for all the circuits schedule 40 okay here?.
You can probably tell, I've not installed a service panel before. What do you think - what am I missing, is there anything else I should ask the inspector?