Adding car charger outlet on existing sauna breaker

Question

I have a house where electrical panel is completely full. I would like to add electric car charger outlet. Electrician suggested new sub-panel - which may be the right thing to do - but is not cheap (labor is very expensive and hard to come by in Truckee where my house is).

I have sauna which has 30A / 208V dual slot breaker. I wonder if I can add an outlet off that circuit - sauna is used very infrequently and I am OK with not charging car at that time.

Thank you

Answer 1

First check if upgrading your existing panel to a larger one with more breaker spaces is an option. Immediately go for the largest possible panel to avoid this exact problem in the future.

If the sauna requires a dedicated circuit then no you cannot just add an outlet to that circuit without splitting the circuit in 2 in a subpanel.

If you do go for a subpanel fed from the sauna circuit. Then you have 2 options to ensure you don't have to cut your sauna session short as the breaker blows.

1. add a mechanical interlock similar as used for a generator hookup so only one of the sauna or EVSE (electrical vehicle supply equipment) gets power at a time.

2. use a smart EVSE which dynamically throttles the power that the car is allowed to pull based on sensing the current in the feed to the subpanel. That way at times when the sauna doesn't need the big heater the car can still be charging.

Answer 2

Don't make the huge and deadly mistake!

Do not put a NEMA 14-50 socket on a 30A breaker!

Imagine you are traveling "on the road". YOu visit friends or a hotel, and want to do "opportunity charging". (ignoring actual EV stations). Which sockets are easiest to find on a road trip? The "normal socket" is everywhere, and RV campgrounds, hotels and friends may have the RV socket NEMA 14-50. So if you were buying a travel charger for that purpose, you'd want those two sockets.

And guess what? Almost every EV comes with that travel charger set exactly!

This has created a misconception that the RV socket NEMA 14-50 is the standard EV socket. No, it's the standard RV socket!

All that to head you off from the grave mistake of adding a NEMA 14-50 socket to the 30A circuit. The EV will go "Oh, I can draw 40 amps!" with catastrophic results if your breakers aren't tip top. Federal Pacific and Zinsco are popular in the west.

So how do we tell the EV what current is safe?

Surprisingly easily, actually.

That lumpy plug is actually a thing called EVSE. It has several jobs, and one of them is telling the EVSE what current is safe to draw. Watch this video here https://www.youtube.com/watch?v=RMxB7zA-e4Y for the gory details on how it does that.

If you're using the little travel EVSE for your daily charging, you notice it has "dongle plugs" that let you swap out which plug it uses. Here's the weird part: a microchip inside the plug tells the EVSE what kind of plug it is. So a 14-50 plug dongle says "yo, 40A" and a "plain plug" dongle says "yo, 15A" etc. Some vendors offer 30-amp dongle plugs and those will correctly signal "Yo, 30A" - that's what you need. Tesla charges $45 for theirs if you have a Tesla.

However you cannot install a NEMA 14-30 socket on the house if the circuit doesn't have a neutral. In that case, install a NEMA 6-30 socket on the house. *If the EVSE vendor doesn't offer a NEMA 6-30 socket, then build a 1-foot "cheater" extension cord with a whatever-30 socket on one end and a 6-30 plug on the other. Make it 1 foot long so it's an obvious cheater cord, so people don't mistake it for a legitimate cord.

Your other option is to go with a "wall unit" type EVSE that is either factory-wired, or switch settable for amps. Buy the right one and/or set it properly, and it will say "yo, 30A" to the EV. That's what you need.

If Tesla, their Wall Connector 3.0 is only $399 and is settable to any breaker amps from 10A to 60A. So on the happy day you are able to upgrade to a bigger electric panel or service, you'll be able to re-commission the Tesla unit to the higher amps.

A few third-party EVSEs can do the same trick, but CrippleCreek units are locked down unfortunately. Unnecessary and sad.

Chinese units off mail order sites are extremely dangerous - they lack GFCI protection, and are shoddily made and will start fires, including burning up the J1772 socket in your car! That won't be a fun conversation at the dealer.

Also consider the used market for quality manufacturer EVSEs. If the unit is UL-Listed, from an established manufacturer like Siemens, and looks like it's in good working order, then it probably is.

Can you add a second outlet onto that circuit? Maybe.

First, you need to answer our questions above. But technically speaking for a non-hardwired, general purpose 30A circuit there is no limit to the number of receptacles. In fact another option is to share the electric dryer circuit.

However in order to extend a circuit, it must be grounded. EVs don't need neutral. If you use a socket with neutral (NEMA 14-30 or others you should not use like 10-30 or 14-50), you must provide the neutral or very bad things will happen when something else is plugged in there.

Answer 3

I wonder if I can add an outlet off that circuit

Technical explanation

Purely electrically speaking yes. It is technically possible to add a standard electrical outlet for the use of your EV off the circuit meant for your sauna. You add a junction box along the wire, connect the right colours together and pop your outlet on the other end.

Be aware that you'll probably have to get an outlet plug to EV Type 2 plug cable (I presume your car takes a Type 2 AC plug) if you don't have one already; these are not always included with the vehicle and cost around $150.

Regulatory/basic safety caveats

I can't answer for your local building regulations which may differ from state to state. So I'll answer just to illustrate the extensive elements of circuit installation design and protection that need to be taken into account. Where I am, we would have to:

• Ensure that the manufacturer's instructions for the sauna do not specify that it has to be on a dedicated circuit. If not, the sauna would have to be disconnected completely.
• Install a type B RCD/GFCI with an "IΔn" of 30mA protecting the circuit at the distribution board (this is so that the circuit can't give people a shock of 30mA or more; if you get much more than 30mA it kind of monkeys with your heart and lung operation, so it can kill people, pets, livestock). Type B is a special type of breaker which handles DC reflection from the EV so it doesn't stop working when you plug it into a car.
• Ensure that the socket outlet (I'm presuming it's outside) is IPX4 rated against water ingress. If it's not, water gets into the electrics and at best makes it stop working. At worst, it could be harmful to life.
• the electrical work signed off by a competent person and have a certificate issued if in a flat, terraced or semidetached house. If a GFCI was added or the sauna removed a competent person would need to provide a certificate regardless. This is because of the increased risk of fire from the new wiring if performed incorrectly. The electrician runs a series of electrical tests with a big expensive meter ($1000+) at 500V to check the wiring and connections are all OK.
• The outlet must have a sticker saying "EV charging". This is one of our new regulations. It's just an indication that it's safe to plug in an EV charger here, if you're not around or have sold the house etc.

Electrician suggested new sub-panel - which may be the right thing to do - but is not cheap

May I suggest as an alternative that you just run an IPX4 extension lead with portable GFCI from an existing house socket, if cost is the ruling factor here, until you can afford to get a professional installer in to do the job properly?

If you have to ask whether it's possible, maybe you don't have the knowledge around safety components, or have access to the specialised test equipment, to perform a safe fixed installation. Your installer costs a lot because of the years of training, exams, and specialised equipment he/she must use to ensure your safety. Saunas have their own specialised regulations for electrical safety. Charging EVs is quite specialised and new even for electricians.