Sound right? Electrician recommended 40A with UF 8/3 outdoor wire to be buried under my concrete

[VTbuckeye]

I;m not sure how you think that would be unsafe.

You can protect a 14-50R with a 40 Amp breaker. Table 210.24:

https://up.codes/s/branch-circuit-requirements-summary

Thanks for correcting me. When I see a 14-50 outlet I assume 50amp construction and capability. As long as the wiring and breaker match then it will be safe. It could be inconvenient if one were to draw 40+ amps on the circuit and the breaker trips shutting down the circuit.

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[Tony Burgh]

NEC/NFPA requires the circuit breaker be 25% greater than the evse output amperage. Wire should be sized for circuit breaker rating.
As the home owner you can do what you want and hope nothing happens. A licensed electrician must follow applicable codes.

 

[Beans]

I’m not an electrician, but from research I believe code requires conduit at least 18 inches below the surface For 240v power.

 

[bewbie]

I was told the outdoor wire would not require conduit. Also, this is for my father who will be getting an ev in the future, my f150 will have the pro charger in the garage next to panel. I am just curious since we are trying to plan for the future, what would be the best setup for my fathers future ev?

 

[PV2EV]

UF-B Is direct burial (no conduit), so upgrading to 6-3 would not require larger conduit, or much more cost if distance is not too much. I would do 6-3, 70 amp breaker and 14-50 outlet.

 

[Amps]

I am just curious since we are trying to plan for the future, what would be the best setup for my fathers future ev?

IMHO, the sweet spot is up-sizing the conductors to #6, install a 14-50R for 40 Amp charging (50 Amp breaker), leaving yourself enough cable to possibly hard-wire an EVSE in for a maximum 48 Amp charging (60 Amp breaker). That means for the increased price of the wire, you get 125% more capability with a receptacle and 150% more capability if you hard-wire, above the 32 Amp maximum you've been quoted.

The caveat is that the entire project conform to code and be inspected, if required.

 

[bewbie]

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-2-awg?ref=5

would this be the best option?

 

[Amps]

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-2-awg?ref=5

would this be the best option?

Only if you hard-wire the EVSE. This to install a 14-50 receptacle, iif conduit is not required:

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-3-awg?ref=5

 

[bewbie]

Only if you hard-wire the EVSE. This to install a 14-50 receptacle, iif conduit is not required:

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-3-awg?ref=5

if its 240v wouldnt i just need 2 hots and a ground? what would be the purpose of having 4 wires?

 

[FlasherZ]

It is legal to install a NEMA 14-50 receptacle with a 40A breaker *IF* the load is designed for it (e.g., if your EVSE can charge at 40A, you're not allowed to do that). 8/3 UF-B cable is good to 40A capacity (because you must use the 60 degC column of ampacity), which is only good for 32A charging because of the 125% capacity for continuous load requirements. You may NOT put a 50A breaker on that installation. That will work for Tesla or Ford mobile chargers that do charging at 32A.

Given that many EV's are targeting 48A charging (60A capacity), if you're doing burial work, I'd bury a conduit and put in #6 THWN. That has 65A capacity on the wires and gives you the most flexibility balanced with lower cost.

Of course, the best flexibility would be to get you a 100A or 125A feeder to your outbuilding, but at some point it gets to be a cost trade-off.

There are also some limitations if you are running this circuit to an existing outbuilding that already has a power feeder to it. Your electrician can help you with the right solution.

 

[FlasherZ]

if its 240v wouldnt i just need 2 hots and a ground? what would be the purpose of having 4 wires?

NEMA 14 series receptacles require a neutral. Never connect a NEMA 14 receptacle with no neutral, and never tie ground to neutral at that receptacle (or you'll find weird ground paths flow through that receptacle).

NEMA 6 series is 2 hots + ground, but EV manufacturers settled on 14-series because of its use with RV's.

 

[bewbie]

It is legal to install a NEMA 14-50 receptacle with a 40A breaker *IF* the load is designed for it (e.g., if your EVSE can charge at 40A, you're not allowed to do that). 8/3 UF-B cable is good to 40A capacity (because you must use the 60 degC column of ampacity), which is only good for 32A charging because of the 125% capacity for continuous load requirements. You may NOT put a 50A breaker on that installation. That will work for Tesla or Ford mobile chargers that do charging at 32A.

Given that many EV's are targeting 48A charging (60A capacity), if you're doing burial work, I'd bury a conduit and put in #6 THWN. That has 65A capacity on the wires and gives you the most flexibility balanced with lower cost.

Of course, the best flexibility would be to get you a 100A or 125A feeder to your outbuilding, but at some point it gets to be a cost trade-off.

There are also some limitations if you are running this circuit to an existing outbuilding that already has a power feeder to it. Your electrician can help you with the right solution.

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-3-awg?ref=5

would this wire work without running conduit?

 

[FlasherZ]

UF-B Is direct burial (no conduit), so upgrading to 6-3 would not require larger conduit, or much more cost if distance is not too much. I would do 6-3, 70 amp breaker and 14-50 outlet.

You may not use a 70A breaker on either a NEMA 14-50 receptacle (50A breaker max) or UF 6-3 conductors. When you use NM cable or UF cable, you must use the 60 degC column for ampacity, and for #6 cable that's only 55A. However, because a 14-50 receptacle is maximum 50A, you may not use more than a 50A breaker to protect it.

The way the NEC works is that it starts with the load. If the load is 55A (after figuring for continuous load requirements or if not required), you select the conductor for the load to be carried (in this case, UF 6/3 would be sufficient), then select the OCPD (breaker) to protect the circuit. Because there is no 55A breaker, a 60A breaker is sufficient.

 

[FlasherZ]

https://www.globalindustrial.com/p/uf-b-underground-feeder-cable-6-3-awg?ref=5

would this wire work without running conduit?

That would work for a maximum of 44A EV charging (55A capacity divided by 1.25 continuous load factor). You would not be able to use that cable with an EVSE that charges a vehicle at 48A. It will work just fine for a NEMA 14-50 receptacle on the end of it with a 50A breaker for 40A EV charging.

 

[bewbie]

That would work for a maximum of 44A EV charging (55A capacity divided by 1.25 continuous load factor). You would not be able to use that cable with an EVSE that charges a vehicle at 48A. It will work just fine for a NEMA 14-50 receptacle on the end of it with a 50A breaker for 40A EV charging.

so what would be needed for an EVSE charger at 48A?

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