Two 240V loads one breaker?

[walta]

Last fall my friend bought an EV and was charging it very slowly with the 120V 15A charger the manufacture provided. It came with a 240 connecter for the charger at 30A or so. As a temporary solution I disconnect the AC unit that he has run maybe 5 times in 20 years. I assumed that it would also be too slow and the charger and service would also get upgraded. I was wrong and 30 A has proven to be acceptable.

The question is since the 10 gage wires are in place is there a code compliant way for the one breaker to serve both loads?

I was thinking maybe a manual transfer switch like the one in this photo would do.

Walta

 

[rlitman]

Well, for starters, your EVSE should be set to 24A if it's on a 30A breaker.

A manual transfer switch is an expensive, but acceptable option, but I wouldn't go that far. I believe there are air conditioners that double as EVSE's, so there are several smarter options to your situation. For example, many EVSE's have interlock outputs that can control equipment, and with the right EVSE, you should be able to disable the AC (either via the thermostat wires or perhaps the contactor low voltage control circuit), so you don't get nuisance breaker trips. Smart panels often have this functionality built in, and may still be cheaper than a MTS.

 

[walta]

I wish I could find a way to set this chargers current draw.

All I can say is people are strange sometimes and the Cadillac came with this charger and seems unlikely he will spend money for another as long as this one is doing the job.

At least the THHN is good for 40 Amps and the breaker hasn’t tripped.

The manual transfer switch I linked to is only $30 complete with a housing.

 

[Shiftless]

How many circuits and how many wires do you have running through that 40 feet of conduit?

 

[dave*99]

I wish I could find a way to set this chargers current draw.

I don’t know the specifics of what charger you are dealing with. But one way or another you must have a way to configure it to the ampacity of the feed circuit. I suspect if it’s not tripping the 30A breaker at least some attempt has been made to do this.

You may not be able to set the charge current to an exact value but you should be able to set the limit to a maximum.

 

[walta]

How many circuits and how many wires do you have running through that 40 feet of conduit?

I did not count the conductors or note the size of the conduit but it was clear that 3 more #6 wires were not going to fit. I assumed it had been installed correctly. Is there something I should be concerned about?

 

[walta]

I don’t know the specifics of what charger you are dealing with. But one way or another you must have a way to configure it to the ampacity of the feed circuit. I suspect if it’s not tripping the 30A breaker at least some attempt has been made to do this.

You may not be able to set the charge current to an exact value but you should be able to set the limit to a maximum.

As best as I can tell when the 120V 15 Amp plug is installed it pulls 12 Amps and with the 240 V 50 Amp plug installed it pulls 32 Amps.

Have a look at eBay item # 366343144785 I think it is the same model. Ultium brand when I looked last fall I did not find much info.

 

[mm08822]

I wish I could find a way to set this chargers current draw.

All I can say is people are strange sometimes and the Cadillac came with this charger and seems unlikely he will spend money for another as long as this one is doing the job.

At least the THHN is good for 40 Amps and the breaker hasn’t tripped.

The manual transfer switch I linked to is only $30 complete with a housing.

#10 copper is not good for 40a, but only 30a ocp max.

40a is the 90C value from which you derate from unless all hardware connections are rated 90C. Panels and cbs are not.

Once there are more than 3 current carrying conductors in that conduit, derating needs to be applied.

That detached garage shouldn't be fed with multiple circuits.

No way this job sounds like it is or could be code compliant w/o significant work.

 

[rlitman]

As best as I can tell when the 120V 15 Amp plug is installed it pulls 12 Amps and with the 240 V 50 Amp plug installed it pulls 32 Amps...

32A on a 50A plug is fine (by those numbers, your EVSE is made for a typical Romex wired 40A ampacity circuit). A NEMA 14-50 50A range plug on a 30A circuit is not fine! If your circuit breaker is 30A, then you need an EVSE that can be programmed to stop at 24A. The EVSE you have is NOT made to be plugged into a 30A circuit.

First thing's first. Stop using that EVSE. Next, have that improper 14-50 outlet removed and replaced with the correct EVSE rated 14-30 "dryer" type outlet, and find an EVSE that plugs into that.

There's a bit to unpack in that. Your EVSE is made to work in a "range" outlet, and if you had a code compliant range outlet, you could safely use it. But your outlet (assuming you're correct about the 30A breaker and 10 gauge wires) is dangerously not code compliant. Your 30A circuit should be able to support a 4-wire "dryer" outlet, so that's where you should be looking.

On top of that, regular outlets should not be used for EVSEs. Nowadays, special EVSE rated outlets are made, because typical "range" and "dryer" outlets have been known to melt from prolonged vehicle charging use.

Is your outlet surface mount, or in a box? I'd need to know before I could recommend something to replace it with.

Once you have a code compliant 14-30 receptacle, we still have to contend with the EVSE and AC simultaneous use issue. If you can get a plug on the AC, and have it reach this outlet, one option would be something like this:

Amazon.com

 

[dave*99]

Here is a thread that explains the Ultium black charger a bit more. The poster had to buy a different charger. Perhaps you can use this thread and the @rlitman post to convince your friend he needs a different charger to use that 30A circuit.

https://www.equinoxevforum.com/threads/evse-died-gm-ultium-evse-with-14-30-plug-adapter-as-replacement.3369/

 

[mike93lx]

My father ran a "dryer buddy" for a few years on a 30a circuit to charge his Kona. It would run at 16a (not sure what the output options were) and it would automatically shut off the evse feed if the dryer was in use. Worked great for him

 

[mm08822]

Need pics of conduit fill, panel, evse and any other hardware in that circuit. Not sounding good from the start.

 

[Shiftless]

How many circuits and how many wires do you have running through that 40 feet of conduit?

I did not count the conductors or note the size of the conduit but it was clear that 3 more #6 wires were not going to fit. I assumed it had been installed correctly. Is there something I should be concerned about?

That detached garage shouldn't be fed with multiple circuits.

Need pics of conduit fill, panel, evse and any other hardware in that circuit. Not sounding good from the start.

mm08822 said it first. The right way to do it is to feed the garage with ONE set of heavy gauge wires and then put the sub panel in the garage. NOT put the sub panel on the house and feed multiple wires with multiple circuits through conduit over to the garage.

 

[dcg9381]

All I can say is people are strange sometimes and the Cadillac came with this charger and seems unlikely he will spend money for another as long as this one is doing the job.

If it's a Cadillac EV, you can set the charge rate on the car. However, the implementation of the EVSE is incorrect if it cannot be setup to limit charge itself correctly to the circuit. Charge rate is negotiated between the EV and EVSE, not all EVs allow you to set charge rate. And not all EVSE's support a 30A connection. EVSE's are cheap enough these days, there is no reason not to buy the correct one for your circuit.

My father ran a "dryer buddy" for a few years on a 30a circuit to charge his Kona. It would run at 16a (not sure what the output options were) and it would automatically shut off the evse feed if the dryer was in use. Worked great for him

This is how I'd do it (with a correct EVSE).

 

[wyliesdiesels]

At least the THHN is good for 40 Amps and the breaker hasn’t tripped.

as has been stated #10 THHN is not rated for 40a but i hope its dual rated THHN/THWN because THHN is not rated for wet locations.

 

[wyliesdiesels]

I did not count the conductors or note the size of the conduit but it was clear that 3 more #6 wires were not going to fit. I assumed it had been installed correctly. Is there something I should be concerned about?

i would pull it all out and run a 4-wire feeder with larger conductors to support more loads on a larger subpanel

 

[Denwood]

What are the AC unit's requirements?

Like a few have posted already I would 100% pull a single conductor and install a sub panel at the garage. The current setup as described would not pass code here as a detached building requires means of disconnect for each circuit in the building. If there is single 30A breaker in that subpanel and multiple circuits connected to it you have a pretty serious fire risk there.

Now, assuming you have a 30A subpanel in the garage, you might consider installing a 20A@240V NEMA 6-20R receptacle in the garage and have your bud use a 16A@240V EVSE instead of the current setup. That adds 10% per hour to a 40kWh pack. That's how I manage EV charging in my shop which is limited to a 30A subpanel. There are no other heavy loads in my shop.

 

[mm08822]

And the garage needs two rods.