Nema 10-30R on Sub-panel for charging?

[ScubaSteve_TheReal]

I have a critical loads sub-panel with a 10-30R generator inlet on a newly purchased property. It is fed from the main panel with a 50amp breaker.
Can this be used for charging purposes also?

I’m hoping to hook up my EV charger with appropriate adapter, say a “Nema 10-30P to 14-50R Pigtail”
and set charger below 24amps or less.
thanks..

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[El Duderino]

The only wrench in your plan is the generator input is not a receptacle. This is by design, so you can't use that breaker to receive power. It should be on a interlock switch on the panel to prevent backfeeding.

The correct way to do this is to install a new breaker, circuit, and 14-50R receptacle.

The other way is as you suggested. I am not sure if the adapter you suggested even exists. Also, does your panel have an interlock switch for that 30amp circuit?

 

[Heliian]

No, you would need a 50a breaker in your critical loads subpanel wired to a 14-50r.

Your probably best off just to do like @El Duderino said and install one in the main panel. You won't need a 240v ev receptacle on generator power anyways.

 

[ScubaSteve_TheReal]

The breakers for the circuits on the sub panel are live feeding those circuits it appears from line power or generator power depending on operation. No interlock..yet. Only instructions from previous owner on turning off mains first..!! , Then turning off all circuits on sub panel and main panel. Then after generator is running and plugged in, turning on desired sub panel circuits. Total old school 20+ year old home setup. Agree it needs an interlock.

On the adapter yes I’ve got one for other purposes. See photo.

So with the subpanel being hot 24/7 and the if an adapter were to be used since the 10-30R is hot wondering if EV charger might be able to be used as expected say at 16amp from adapter from this?

I do plan getting electrician but for short term weekend only…

 

[El Duderino]

Just be careful and mindful of what you are doing. More so when you use a generator or backup power with that setup.

 

[21st Century Truck]

FYI - pls note "rated for 30 amps". The Ford OEM cord-with-brick EVSE pulls up to 32 amps during steady charging, which exceeds this adapter's and the NEMA receptacle's rating.

There are solid adapters like this without the cord in between their business ends. I have one, and others for other 240V receptacles... and I also have an aftermarket EVSE cord with user-variable amperage settings.

 

[Heliian]

Total old school 20+ year old home setup. Agree it needs an interlock.

Oh, in that case, just change it all to work properly. It's a very small investment that is much cheaper than having a deadly accident.

Suicide cords and manual switching without interlocks is recipe for disaster.

 

[bc1]

If I'm reading you right, this is critical loads panel is just a subpanel going to certain loads such as heating, lights, and just enough to hold you over in an emergency but also has a with a 50 amp breaker at the main panel with a 10-30R receptacle as a way to connect a generator without following NEC codes unless you are in a rural situation that may not be covered by a code or was not covered in the past.

Critical loads are the ones you need to be using all the time. The critical loads may be using enough amperage that just a little more could trip the 50 amp breaker or worse cause the wiring to melt and start a fire if the breaker is oversized.

I would want to know the following and a few pictures would help:

What size, type, gauges of wire, and number of conductors inside are going from the panels and if there is a ground wire. It should say on the outside sheath. The ground may be a smaller size wire.

How long is the distance in feet for that wire between the panels. The 50 amp breaker is sized to protect the wire from melting so the distance and gauge of wire makes a difference.

The same two requests apply to the wire/conductors that goes to the receptacle from the subpanel.

With a clamp on ammeter, measure the amperage flowing through the wires between the panel and subpanel when everything is running. If all your critical loads are already pulling 30 or 40 amps, there isn't much left to charge with. Or at least list what all the loads are that are running off the subpanel and that can be calculated. You may plug in and trip the breaker or overload the wires.

Depending upon the above, there may a small chance you could add short run of wire from the subpanel to a 14-50R or possible replace the 30 amp receptacle with a 14-50 but it doesn't sound good.

A new subpanel setup like what is used for hot tubs or an outside air conditioner condenser may be called for. If so I would put in an RV type panel and/or go to the interlock if you plan to get a generator or use the truck to power the home in an emergency. If so you still need to know what the load is going to be.

You may not overload it if you come off of the 30 amp receptacle with an adapter from a 10-30P (plug) to a regular 120 volt receptacle. It would be slow charging but better than nothing.

You might luck out and the loads are such that you can charge like you want to. But then it may trip everything in the middle of the night in the winter.

 

[ScubaSteve_TheReal]

Thank you for such detail and considerate response. I know I will hopefully get my Ford Pro Power 80amp unit wired in by an electrician asap. This temporary inlet approach idea was for weekend usage until then if viable. At that time I’ll address the inlet and even a possible 14-50R as a secondary option for just whatever.

My temporary 240 volt charger current
Is changeable to 10A 16A 24A 32A so I had figured 10A or 16A would more than suffice. The current generator 30amp 10-30R inlet was just there, 2-3” below sub panel. For reference we just moved in. It’s a rural 23 year old property with 200amp service fyi. I’ll have to do some more additional tests and research on what I’ve got going on. For reference see photos. Please ignore dirt dauber mess I’m cleaning it off gently later.
Either way thank you.

 

[bc1]

There should be a couple screws to take the cover off of the breakers exposing the wiring and maybe you can see enough of the sheath to get a wire size but a pic would help. That would be where to read the amps with a clamp on meter.

I see two 50 amp breakers and I would guess one is the input from the main panel and one goes to the 30 amp receptacle which would be the "manual" way of switching off the main power before switching the other one from the generator to on. You have no generator on and connected but both breakers are switched on. I would want to see if you have 120 volts to ground coming from each side of the receptacle for a total of 240 volts with a tester. If you got juice going to your receptacle and adapter then you have a live circuit if something is plugged.

That said, I would want to see the main 200 amp service panel pics and identify the outgoing breaker and wiring to the subpanel as well as a pic with the cover off and that is the breaker that energizes that circuit. The 50 amp breaker mentioned above may only be serving as an on/off switch and have nothing to do with being the breaker that protects the wiring from fire and overload.

This is wall mounted outside under cover apparently. Still like to know the distance to the main panel.

Looks like a few rooms of lights and receptacles along with a dishwasher and septic pump. Not a great load but don't run the dishwasher while plugged in to charge. You can experiment with charge levels starting with the lowest until you trip the breaker then you will know. If you can live with that charge level below tripping the breaker then you would be OK. If you are running any high amp/wattage devices that can makes things worse such as electric heaters or skill saws or air compressors then don't use them.

The septic pump motor if it has one will have a surge when it starts so if not running and it kicks on, then it may trip the breaker so you would have to reduce your charge amps. Start running water to kick it on to test what it does to your load.

I can't tell if the stove and oven are connected or not which would make a difference if running or an air fryer being used, etc. which would increase the load and not to run while charging.

 

[Maquis]

Thank you for such detail and considerate response. I know I will hopefully get my Ford Pro Power 80amp unit wired in by an electrician asap. This temporary inlet approach idea was for weekend usage until then if viable. At that time I’ll address the inlet and even a possible 14-50R as a secondary option for just whatever.

My temporary 240 volt charger current
Is changeable to 10A 16A 24A 32A so I had figured 10A or 16A would more than suffice. The current generator 30amp 10-30R inlet was just there, 2-3” below sub panel. For reference we just moved in. It’s a rural 23 year old property with 200amp service fyi. I’ll have to do done additional tests and research on what I’ve got going on. For reference see photos. Please ignore dirt dauber mess I’m cleaning it off gently later.
Either way thank you.

If this is what you’re calling a “generator inlet”, it’s not.

 

[bc1]

If this is what you’re calling a “generator inlet”, it’s not.

Yep. Possibly an outlet for a 30 amp RV plug.

But it could also serve as a manual one not up to Code. I've kept a house warm for a week one winter power outage with the main breaker in the off position and a little 2250 watt generator plugged into a 120v outlet just to run the gas heater blower and a few lights. Not code but I know what I was doing as the main breaker was off and no power would enter when the power company did restore power. Generator was on the porch.

 

[RLXXI]

Yep. Possibly an outlet for a 30 amp RV plug.

But it could also serve as a manual one not up to Code. I've kept a house warm for a week one winter power outage with the main breaker in the off position and a little 2250 watt generator plugged into a 120v outlet just to run the gas heater blower and a few lights. Not code but I know what I was doing as the main breaker was off and no power would enter when the power company did restore power. Generator was on the porch.

Our clothes dryer uses that exact outlet and I too have used it in an emergency to back feed power with our backup gen when the whole home gen decided to take a vacation after a hurricane blew thru.

Just couldn't use any high current devices, central heater, oven, cook top, clothes dryer, water heater. (Total electric home) only gas is to feed the big gen.

Cold showers are no one's envy so I swapped out the water heater for one with heat pump tech. Now when the power drops if the big gen fails ,the little gen will power the water heater with ease.

 

[bc1]

I might add that if by chance those two 50 amp breakers on the subpanel are there with one as a shut off to the incoming power and the other a breaker for a receptacle to take an incoming generator, they make a mechanical type lockout that screws onto the panel over the breakers that switches them together that is code compliant for generator connection in some places. You couldn't plug in a dryer or RV and power them however.

I still want to see what kind of wiring is behind that panel. A 50 amp breaker on a 30 amp receptacle is too much depending upon the conductor size although it is a very short run. 6 gauge conductors would be great but could be 8 or more likely 10 gauge which would allow 30 amps. But all that also depends upon the conductor size coming from the service entrance main panel.

If you want to charge at more than 24 to 30 amps (depending upon what the insides of the panels reveals on wiring and distances, etc.) then you will need a new feed to a new subpanel from the Service Entrance main 200 amp panel IMHO. And at the same time have the electrician bring/replace the other panel so it is code compliant as an interlock for generators.

 

[ScubaSteve_TheReal]

Didn’t have much time as hoped today, however I do have 240v at the 10-30R outlet. Here is a couple pics left for us from the now deceased homeowners and said usage instructions.

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