40 amp or 50 amp?

[timbop]

Please excuse my use of imprecise terms….

I’m running 220v to the garage - I was going to use and existing 40 amp breaker with 8 gauge wire.

I’d like NOT to buy a $700.00 charging station…will the charging devices Ford provide put 220v into the car?

So, will 40 amps / 8 gauge work? Or is 50 amp / 6 gauge required to work with Ford’s charging devices.?

thank you!

Yes, a 40Amp breaker with 8 gauge wire and nema 14-50 outlet will work if you use the "mobile" charger that comes with the car. It will also work with an aftermarket charger, but you will have to configure that aftermarket charger to use no more than 32A.

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[Cooper]

I’m new to this Forum - first message. I have a 2021 GT PE, Grabber Blue. Just had the electrician install the 240 plug in the garage and 40AMP breakers on the box. Problem is, when using the provided Ford charge cord, I’m still charging at the same speed as the 120 plug?

Also, I saw someone posted a calculation to determine the time miles charged per hour when using this setup but I can’t find it again. Can someone copy and repost?

 

[mkhuffman]

I’m new to this Forum - first message. I have a 2021 GT PE, Grabber Blue. Just had the electrician install the 240 plug in the garage and 40AMP breakers on the box. Problem is, when using the provided Ford charge cord, I’m still charging at the same speed as the 120 plug?

Also, I saw someone posted a calculation to determine the time miles charged per hour when using this setup but I can’t find it again. Can someone copy and repost?

It's the second post in this thread.
https://www.macheforum.com/site/threads/40-amp-or-50-amp.15550/post-372301

I don't like using miles added because it assumes a specific efficiency that you might not get. It is better to look at the charging speed and how many kW you can add per hour, IMO.

 

[Mach-Lee]

I’m new to this Forum - first message. I have a 2021 GT PE, Grabber Blue. Just had the electrician install the 240 plug in the garage and 40AMP breakers on the box. Problem is, when using the provided Ford charge cord, I’m still charging at the same speed as the 120 plug?

Also, I saw someone posted a calculation to determine the time miles charged per hour when using this setup but I can’t find it again. Can someone copy and repost?

That seems impossible, did he check that the outlet was wired correctly? 120V to ground at the two outside slots and 240V between the two outside slots.

Charging MPH = (W * % efficiency) / (Wh/mi) or (kW * % efficiency * mi/kWh) depending on which units you like. 240V charging efficiency is around 90% IIRC.

 

[mkhuffman]

See above, you are fine doing 8 ga 40A if you don’t want to pay more.

It's not that much more and I think it is a really bad idea to wire a 14-50 outlet with wire that cannot handle what the outlet is rated for.

Yes you can protect the wire with a 40 Amp breaker, but some knucklehead will see the 14-50 outlet and replace the breaker with a 50 Amp one thinking it will be fine, not knowing the wire is not sized for 50 Amps. It is better to be safe and wire it for 50 Amps.

 

[Mach-Lee]

It's not that much more and I think it is a really bad idea to wire a 14-50 outlet with wire that cannot handle what the outlet is rated for.

Yes you can protect the wire with a 40 Amp breaker, but some knucklehead will see the 14-50 outlet and replace the breaker with a 50 Amp one thinking it will be fine, not knowing the wire is not sized for 50 Amps. It is better to be safe and wire it for 50 Amps.

I understand your point, but electricians have been installing 50A outlets on 40A circuits for many decades, long before we were born. The outlet behind your kitchen range is most likely a NEMA 14-50 on a 40A breaker. With the price of copper, it's very common to see 6 gauge aluminum wire used for 14-50 outlets nowadays which has a 40A max rating. While it may seem foolhardy, my point is using a 14-50 with a 40A breaker is a well-established practice in the electrical trade that won't raise any concerns among professional electricians or inspectors. Installing 40A instead of 50A does provide some cost savings if you only want to use the Mobile Charger at 32A. It is perfectly safe to do that. It is not the job of the electrical code to make everything idiot-proof, that still lies with the end-user. If someone is dumb enough to install an EVSE without checking rating or swaps out the breaker, they deserve the liability on that.

Once garage EV outlets become required by code in new houses, expect most of them to be 40A circuits with NEMA 6-50 receptacles (no neutral wire). This is because of cost savings (builders will use the minimum required by code). You will have to pay extra to get 50A or a 14-50 in your new house as an upgrade. By this point in time 40A EV circuits will be more mainstream/accepted. Ford had already thought of this, which is why the Mobile Charger is set to 32A (safe to use in any NEMA 14-50 outlet, 40A or 50A).

If someone was really worried about their 50A outlet on 40A circuit, they could put a sticker on it labeling it as 40A.

Current cost difference between 40A and 50A is about $40-100 depending on length (more with electrician markup). I'll admit that's probably not a big deal for most Mach-E buyers but it might be for working class folks trying to get an EV outlet installed at the minimum cost. 40A wire is also a lot easier to work with than 50A wire.

 

[mkhuffman]

40A wire is also a lot easier to work with than 50A wire.

This is true, and wiring the outlet with 50A wire is frustratingly difficult (unless you have done a lot of them I suppose). And I agree with your other points, but I would spend the extra $100 and then not worry about it. Because knuckleheads exist. And 40 Amp chargers exist.

 

[WyldStallyn]

Ultimately, if you have an existing 220V/40A circuit then it is perfectly fine to use a 14-50 receptacle. However, if you are running a new circuit anyway then I highly recommend future-proofing as much as you are able.

In my case, I ran 4AWG to my charger which allows me charge up to 48A on a 60A breaker. I am hardwired but I could have also used a 50A breaker and a 14-50 receptacle.

 

[mkhuffman]

I am hardwired but I could have also used a 50A breaker and a 14-50 receptacle.

48 Amps continuous will eventually cause a 50 Amp breaker to throw. You should only pull 80% of the current rating to avoid that. Hence a 40 Amp circuit is needed for a 32 Amp constant load. And a 60 Amp circuit is needed for a 48 Amp load.

 

[WyldStallyn]

48 Amps continuous will eventually cause a 50 Amp breaker to throw. You should only pull 80% of the current rating to avoid that. Hence a 40 Amp circuit is needed for a 32 Amp constant load. And a 60 Amp circuit is needed for a 48 Amp load.

Correct. My point was related more to the wire size as that is the most difficult to upgrade in most cases. I wasn't clear that changing to a 50A breaker would require setting the charger to limit current to 40A.

 

[v8318cid]

Another factor that I do not think I've seen discussed here is the distance the wire will cover. Longer runs will require a numerically lower gauge of wire as resistance increases over longer distances. Shorter runs less than about 30 feet should be fine with 4AWG or 6AWG wires with a 40 or 50 amp circuit. However, if you run from one end of the house to the other, thicker wire will probably be needed. A quick Google search should provide high level guidance on this. As always, consult with a professional/licensed electrician for the most trustworthy guidance.

 

[Scooby24]

Another factor that I do not think I've seen discussed here is the distance the wire will cover. Longer runs will require a numerically lower gauge of wire as resistance increases over longer distances. Shorter runs less than about 30 feet should be fine with 4AWG or 6AWG wires with a 40 or 50 amp circuit. However, if you run from one end of the house to the other, thicker wire will probably be needed. A quick Google search should provide high level guidance on this. As always, consult with a professional/licensed electrician for the most trustworthy guidance.

I think 6* is fine for 50 amp up to around 150 feet. *Copper

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