generator transfer switch

chuck172

I'm installing a generator 6 circut manual transfer switch. Looks like I need to either splice the circuts in the load center (circut breaker box) and bring the wires out to the transfer switch, or I can pull the wires out of the load center and add junction boxes and then route the circuts to the new generator transfer switch.
I have the room in the load center. I'd prefer this method. Is it up to code?

chuck172

Any answers? I'd like to get started on this.

AllanJ

Doing all the splicing in the load center is topologically equal to using the load center as a pass through. This is not permitted in some local cities' code.

With that many (six) circuits, the load center would be much cleaner if you withdraw the circuit cables in question from the load center and use a separate junction box.

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The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

chuck172

Can I fit all 6 circuit splices in one junction box?
What size box should I get?

AllanJ

Get a 59 cubic inch box for 12 gauge wiring (52 ci for all 14 gauge).

Be sure there are enough holes for the various cables going in. Usually one hole (with appropriate clamp) can admit two Romex cables.

Connect each circuit neutral only to the neutral that accompanies the corresponding hot wire going to a switch.

Connect all ground wires together in the junction box. You can group the ground wires into bundles with jumper wires (pigtails) connecting the bundles.

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The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.

brric

Provided there is adequate space, splicing in the load center is acceptable in most cases. Generac transfer switches are manufactured that way.

chuck172

Can two romex 12/3 wires go through the same knockout and both share the same clamp?

brric

If the clamp is listed for two cables, yes. If you are considering shared neutrals make sure the tranfer switch is compatible for that configuration.

Jim Port

Typically the NM clamps are for 2 flat cables like 14-2, but only one 3 wire like 14-3. Check the packaging.

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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.