Multiple NEMA 10-30 receptacles on one circuit?
July 10, 2020 3:38 PM   Subscribe

Does the national electrical code permit multiple 30A outlets on one 30A 220V circuit?

My garage has one NEMA 10-30 outlet at one end for the dryer. I'd like to add another receptacle at the other end to charge a car. The charger has an adapter and works well on 30 amps. It's easy enough to use only one device at a time, but I'm wondering if two outlets on one circuit would pass inspection? Google results have been conflicting.

Related: does anyone know a go-to place for code-related electrical questions?
posted by Wembly to Home & Garden (6 answers total)
Best answer: No.
NEC 625.40 Electric Vehicle Branch Circuit. Each outlet installed for the purpose of charging electric vehicles shall be supplied by an individual branch circuit. Each circuit shall have no other outlets.
posted by Consult The Oracle at 3:56 PM on July 10, 2020

You can access the National Electrical Code for free by creating a login, but the NEC is not really intended to be interpreted by a layperson. But at least you should be able to look in the actual text.

(Note also that most locations adopt the NEC, but not all the same versions at the same time. I also have a response in MeMail, but it doesn't answer your question yet.)
posted by Huffy Puffy at 3:56 PM on July 10, 2020

625.40 notwithstanding...The other issue is that a branch circuit without a separate ground (3-wire normal wiring for legacy NEMA 10-30) must be contiguous between the panel and the outlet. Obviously, "extending" that branch circuit would be in violation if the branch circuit was not 4-wire.
posted by Consult The Oracle at 4:04 PM on July 10, 2020

Tangential to your question... but this is a potential solution:

It's basically a splitter that sends power to your dryer when it's running but otherwise sends power to the car. Only one outlet can be active at a time, so the total draw is limited to what it would be with a single outlet.

I have one at work for obscure and complicated reasons, and it seems like a well-built piece of equipment.
posted by mr_roboto at 5:02 PM on July 10, 2020 [5 favorites]

Another dodge is to install a 4 cct 30A sub panel with the dryer feeder and then drop a 30 Dryer receptacle and 30A charger circuit off the sub. You have to manage the switch between manually by just not running both at the same time or lock out can be enforced with a bolt on interlock kit. All the rules that require dedicated circuits only apply as far as the new sub panel.

This won't work if you don't have four wires (white, black red, bare/green) in the cable feeding the dryer.
posted by Mitheral at 5:57 PM on July 10, 2020 [1 favorite]

My go-to on electrical code is the ever-vastening Wiring Simplified. It's updated regularly, so get the latest one and shun the old ones.
posted by the Real Dan at 6:06 PM on July 10, 2020 [2 favorites]

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