Subpanel conduit question


Old 06-13-09, 02:54 PM
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Subpanel conduit question

I need to install a subpanel in an attached shop room. I plan to run PVC conduit thru the outside wall of my home below the main panel, across the wall about 12 feet and thru the outside wall of the attached shop room to the subpanel box. I plan to use 3 THHN conductors and a bare ground wire, appropriately sized for the breaker feeding the subpanel.

I am uncertain about routing the feeder wires from the bottom of the interior flush-mounted main panel and the end of the conduit where it penetrates the outside wall.

Does the conduit have to be connected to the bottom of the main panel?

If not, are the feeder wires just bundled together and clamped/stapled to the studs inside the wall under the main panel and passed thru a suitable cable clamp in the bottom of the main panel?

If the conduit only needs to penetrate the wall, is there a special bushing or other fitting to be used on the end of the conduit where the feeder wires enter?

The subpanel in the shop will be surface mounted and the conduit will extend clear to the subpanel box.

Thank you for any advice you can give me.
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Old 06-13-09, 08:01 PM
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The conduit needs to enter the panel with a nipple connector.
Old 06-14-09, 12:26 AM
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You don't want to enter the bottom. If your panel is flush mounted and the sub panel is flush mounted. You intend on running PVC via the exterior of the home. You will exit the main panel through the back of the panel. All panels usually have 4 knock-outs on the back towards each corner. You exit 1 panel via the back and enter the other in the same fashion.

You will want to use an LB at the hole in the siding and a box adapter with locknut and plastic bushing where entering the back of the panel.

Parts List:
2 LB's
2 TA's
2 Locknuts
2 Bushings
2 Sticks of Conduit
3 Rigid 2 hole straps
4x22' THHN

You don't run bare conductors for the ground. if your wires are #6 or smaller they have to be colored conductors. (Black, Red, White, Green) If large than, you can use all black and color the ends with phase tape.

Lastly, Don't forget that ground and neutrals are separate in a sub panel. So if it doesn't already have one, you will need to buy a separate ground bar and don't install the green bonding screw (or remove the ground strap, depending on panel brand)

Good luck
Tom McGuire

Last edited by GregH; 06-14-09 at 06:52 AM. Reason: Remove link
Old 06-14-09, 09:53 AM
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Thanks Hiloelectric for your detailed reply. That is just the information I was looking for. I appreciate you taking the time to reply and share your expertise.

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