Electrician question

[dw0095]

I'm expecting to take ownership of my MME June 30th and prepping the garage charging. I plan to use the charger it comes with and my electrician is questioning the specs I requested based on this table from the ford brochure. It says 240/30A NEMA 14-50 outlet. He is saying that the NEMA is for a 50A circuit so why am I asking for a 30A circuit. What specs do I need to use the supplied charger? I'm very out of my league here.

He is also telling me about aluminum wire because copper prices are so high. I trust him but not sure what is best here. Cheaper wire or expensive.

Thanks!

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[kdryden99]

I'm expecting to take ownership of my MME June 30th and prepping the garage charging. I plan to use the charger it comes with and my electrician is questioning the specs I requested based on this table from the ford brochure. It says 240/30A NEMA 14-50 outlet. He is saying that the NEMA is for a 50A circuit so why am I asking for a 30A circuit. What specs do I need to use the supplied charger? I'm very out of my league here.

He is also telling me about aluminum wire because copper prices are so high. I trust him but not sure what is best here. Cheaper wire or expensive.

Thanks!

You should have wiring capable of handling up to 50 amps hence the 14/50 plug. The charger uses up to 32 amps so your electrician would put a 40amp breaker. If ever you change to an EVSE capable of 40+ amps you can just have the breaker swapped out. As for the wiring, I have always felt that if you do something do it right. Copper all the way. I still don't trust aluminium wiring and with such a large amount of current draw I'd stick with copper. At the end of the day if you can pay for it and the difference in cost doesn't bother you then pay the extra.

 

[timbop]

That's a misprint. You need a minimum of a 40A circuit on a NEMA 14-50 outlet, but the "right" way to do it is to run a 50A circuit. The mobile charger only draws 32A, but because it is a continuous load for more than 3 hours the circuit itself has to be rated for 25% more than what the charger is actually going to draw. So, for a 32A charger the circuit must be at least 40A. While you can connect a 14-50 outlet to a 40A circuit, the cost difference in running a 50A vs 40A is not very much. By running a 50A circuit if you replace the Ford mobile charger with a 40A charger (that charges 20% faster than a 32A) you will be all set.

 

[RonTCat]

I'm expecting to take ownership of my MME June 30th and prepping the garage charging. I plan to use the charger it comes with and my electrician is questioning the specs I requested based on this table from the ford brochure. It says 240/30A NEMA 14-50 outlet. He is saying that the NEMA is for a 50A circuit so why am I asking for a 30A circuit. What specs do I need to use the supplied charger? I'm very out of my league here.

He is also telling me about aluminum wire because copper prices are so high. I trust him but not sure what is best here. Cheaper wire or expensive.

Thanks!

Your electrician is correct. The Ford Mobile Charger draws ~32amps, and circuit breakers can only handle 80 percent of their rating, so a 40 amp breaker X .8 =32 amps is the MINIMUM you need. Likely 99% of people install a 50amp circuit just to have a safety margin. The "50" on 14-50 means the outlet is rated for 50amps. If you go aluminum, I would absolutely go with a 50 amp circuit.

 

[Garbone]

As I ran mine in 3/4 conduit I used #6 THHN and the appropriate breaker. The wire can handle up to 60amps so if in the future I want to do a hard wire 48 amp charger instead of a 14-50 socket all is ready.

 

[RonTCat]

You should have wiring capable of handling up to 50 amps hence the 14/50 plug. The charger uses up to 32 amps so your electrician would put a 40amp breaker. If ever you change to an EVSE capable of 40+ amps you can just have the breaker swapped out. As for the wiring, I have always felt that if you do something do it right. Copper all the way. I still don't trust aluminium wiring and with such a large amount of current draw I'd stick with copper. At the end of the day if you can pay for it and the difference in cost doesn't bother you then pay the extra.

Aluminum is softer than copper, so the connections have to be extremely tight when they are first installed, as they tend to loosen over time as the aluminum "flows" a bit. It's likely why most people are a little leery of Aluminum wiring. Aluminum is fine, but I likely would go back and re-tighten all the Aluminum connections after a year of so, then you are all set.

 

[timbop]

I have a house with some aluminum circuits in it, and I would avoid aluminum if I were you. I have had 2 issues with connections loosening as @RonTCat mentioned, 1 of which literally melted a switch and could have easily caused a fire. If your electrician runs it he will likely use a special paste in the connections specifically to address the loosening issue, but it is not worth fooling around with - go with copper.

The full story: on christmas morning in 1996 we woke up to a freezing cold house. It turned out that the connection from the heater blower to the emergency shutoff switch worked its way loose and was arcing. This happens because aluminum is soft and when it heats up and then cools off over time the wire flattens out just a little bit and causes a gap to form. It got hot enough to melt the plastic around the screw terminal on the switch, allowing the screwpost to come free from the switch body. We were extremely lucky; had the screw post not come loose to interrupt the circuit I am sure there would have been a fire. The switch body was blackened, and in the attic the paper facing on the insulation that was sitting on top of the wire has a blackened line all along it. The house was built in 1973, so it took 23 years to happen.

 

[ZuleMME]

Always remember the breaker is to protect the wiring from exceeding it's design capacity. Not to limit the end device. Plugging in a 16a, 24a, 30a, 32a etc device on a 50a capable circuit are all completely acceptable. If you plug in a 52a (or say 45A continuous) device on a 50A breaker the breaker trips to prevent you from drawing the current over the wire which wasn't rated for that level. That's it. EVSE's actually don't limit current either! They simply communicate with the car charger to tell it what it's connected to and can draw.

 

[Superdeg]

I'm expecting to take ownership of my MME June 30th and prepping the garage charging. I plan to use the charger it comes with and my electrician is questioning the specs I requested based on this table from the ford brochure. It says 240/30A NEMA 14-50 outlet. He is saying that the NEMA is for a 50A circuit so why am I asking for a 30A circuit. What specs do I need to use the supplied charger? I'm very out of my league here.

He is also telling me about aluminum wire because copper prices are so high. I trust him but not sure what is best here. Cheaper wire or expensive.

Thanks!

You need a 50 amp circuit with a 50 amp GFIC breaker. I would use copper for the reasons indicated plus using aluminum potentially may impact your homeowners insurance rate. I had a copper 50 amp circuit run by a licensed electrician 9 months ago with zero issues. Enjoy your new pony!

 

[TheVirtualTim]

Your electrician needs to install wiring and a breaker that handles 50 amps for your NEMA 14-50 outlet.

The car is not permitted to pull more than 40 amps when using that receptacle. This is because the National Electric Code defines any load that can last longer than 3 hours as a "continuous" load (and charging an EV can easily take more than 3 hours). Circuits supplying a "continuous" load must be rated to handle 125% of the load (so 125% of 40 amps is 50 amps). OR ... another way of saying it is that no device should pull more than 80% of what the circuit was designed to handle.

The Ford Mobile Charger that comes with the car only pulls 32 amps ... but you may decide to get another charger someday and you'll want to know that your receptacle (rated for 50 amps) really has the wiring to handle it without risk of overheating.

I had my electrician pull wire rated for 60 amps ... even though it was to a NEMA 14-50 (50 amp) outlet. I did this because who knows if I might want to remove the outlet and replace it with a hard-wire wall-mounted charger.

 

[mkhuffman]

I agree with the other posts about a 14-50 plug, wire and 50 Amp breaker. Except I didn't install a GFCI breaker, which I know is not up to code. The main reason I didn't is because some have reported problems with breakers incorrectly turning off when a GFCI charger is used. This may or may not be a problem for me, but the non-GFCI breaker is much cheaper, and much easier to find in the world of shortages, so I just did that. A licensed electrician will probably not agree to install anything that is not up to code. I am not a licensed electrician, I just play one on TV.

Edit: I ran 60 Amp cable to a sub panel and ran the 50 Amp outlet from the sub panel. This past weekend I also installed a direct wire charger that is 48 Amps. Love it. Now I have both the outlet and the hard wired charger. I briefly considered running 120 Amps to a sub panel but the wire size to do that is huge and I decided it was not worth it. Hopefully I won't regret that decision.

One day when we sell the house and if the house inspector flags the non-GFCI breaker as an issue, I will pop a GFCI breaker in. Easy fix.

 

[BMT1071]

You guys realize this is a 6 month old post that some noob resurrected to add absolutely nothing, right???

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