Preparing for Mach-E charging at home - preparation and installing charger

[Illinibird]

Electrical engineer here. There's a lot of discussion going on here about 240 V install and GFCI. Thought I'd throw my $0.02 in for reference. The typical residential service coming into your house from your utility in the USA is 240 V (kind of). There are three wires: Neutral, +120 V and -120V. If you look inside your breaker box, there is a 'zig zagged' set of buss bars that are interleaved that your breakers connect to. One is connected to +120 V and one is connected to -120 V. When you install a single width breaker, you're making a 120 V circuit. You're connect one wire (hot / black) to EITHER +120 V OR -120 V and the other wire to neutral which is 0 V (neutral / white). You the run this to your outlet and the voltage you get is the difference between +/- 120 V and 0 V (either results in 120 V).

Now when you want a 240 V outlet, you use a double-wide breaker. This is the reason the buss bars are zig-zagged because the double breaker connects one side to a +120 V and the other to -120 V. Then you run this to the outlet with black/red to the +/- 120 V connection. You don't need the neutral in this case... BUT some outlets bring it out (white wire) as is done in a NEMA 14-50 outlet. Then the thing you plug in uses the difference between +120 V and -120 V and you get 240 V! If the end device also wants 120 V, then it can use the neutral. This is what something like an electric dryer does for the lower power electronics... it uses 240 V for the heating element and 120 V for the control electronics and lights.

The circuit breaker is there to protect your wires from catching on fire in the event of a short circuit. It is NOT there to protect you from being electrocuted for two reasons. Your hand might not draw enough current to trip the breaker but still get a potentially lethal shock. And because a circuit breaker trips much too slowly to protect you even if it does trip. That's where a GFCI comes in. It is a Ground Fault Circuit Interrupter. They are designed to protect YOU not the wires. They work by measuring the difference between what goes out one end and comes back in the other. Under normal circumstances, all of what goes out one side comes back the other. If there is an imbalance, it must be going somewhere else (like into you). That's why they're required in places where there is a potential shock hazard (kitchen and bathroom). As soon as it detects an imbalance measured in milliamps, it trips.

This comes to the point of needing one or not for a car charger. A charger that doesn't include a built-in GFCI will ask for one to be installed, like the Ford Mobile Charger. One that does have one built in will ask you to not to install one, like the hardwired Ford charger. However, if you don't have a GFCI breaker, then you're only protected from the point where the GFCI is to the end, so in the example of a hard wired charger, you're only protected in the connector of the charger, if you touched the wiring to it, you'd get shocked unprotected. It would be smart to include a GFCI breaker if you have an outlet that you're plugging/unplugging repeatedly as the GFCI breaker will protect you at the plug, so if when you're unplugging it, it won't shock you if you touch the prongs of the plug.

Now you might think, why don't we always just use a GFCI breaker then? Well the way a GFCI protected EV charger works is that it first verifies that the ground connection is working by sending some current through there... which if you had a downstream GFCI breaker, would be detected as a ground fault and cause a nuisance trip. So this can result in a lot of nuisance trips.

I'm happy to entertain questions, but I want to emphasize that this is all the more reason why you shouldn't be doing this if you're not comfortable or knowledgeable about this. I didn't even list all of the things to consider like wire and conduit sizing.

EDIT: For reference, here's a great video explaining the 240 V panel:

Great explanation! You left out the gauge of wires used for 50 amp breaker versus 60 amp breaker and also diameter of conduit for each. I have short run from 200 amp panel to 14-50 NEMA outlet. What gauge wire can I get away with? Do I have to replace the existing conduit? (larger conduit - larger knockout plug).

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[machefan]

Now you might think, why don't we always just use a GFCI breaker then? Well the way a GFCI protected EV charger works is that it first verifies that the ground connection is working by sending some current through there... which if you had a downstream GFCI breaker, would be detected as a ground fault and cause a nuisance trip. So this can result in a lot of nuisance trips.

Just for those who didn't ask, I am going to simply this as the Ford manual makes it a 50/50 answer.

Plug-in included Ford charger = GFCI recommend
Wired direct charger = GFCI will not work due to the internal one.

It's in the manual.

Note that the manual is 60A for the direct wired charger and 50A for the plug-in. However the spec sheet does not include the electrical aspects, will see if I can find them. AMP draw, total kw output etc.

 

[machefan]

Great explanation! You left out the gauge of wires used for 50 amp breaker versus 60 amp breaker and also diameter of conduit for each. I have short run from 200 amp panel to 14-50 NEMA outlet. What gauge wire can I get away with? Do I have to replace the existing conduit? (larger conduit - larger knockout plug).

The non-conduit answer is NM-B 6-3 is up to 50 AMPS, but there are two more types of 6-3 that go beyond the 50 AMPS.

 

[CHeil402]

Great explanation! You left out the gauge of wires used for 50 amp breaker versus 60 amp breaker and also diameter of conduit for each. I have short run from 200 amp panel to 14-50 NEMA outlet. What gauge wire can I get away with? Do I have to replace the existing conduit? (larger conduit - larger knockout plug).

Sorry, I didn't go back far enough to read your initial question. To clarify, it seems that you had the wiring and conduit installed to be rated for a future upgrade to a hardwire connection. This is good future proofing. That being said, a NEMA 14-50 outlet must have a 50 A breaker. If you put a 60 A breaker on it, you're violating code as it's not rated for that. Technically, the Ford charger would only be pulling 32 A even if you put a 60 A breaker, because the NEMA 14-50 is only rated to 40 A continuous max but you can't rely on a well behaved end device, hence the code.

So if you installed 'future proof' wire and conduit rated for 60 A but is currently connected to a NEMA 14-50, then it should be a 50 A GFCI breaker. If you upgrade that in the future to a hardwired connection, at that time you can replace the breaker with a 60 A non-GFCI breaker.

Individual conductors, like THHN are rated for higher current at the equivalent wire size to a Romex (NM-B) wire that doesn't install in conduit. It's all based on temperature rise and an NM-B wire has more insulation. See here: https://www.wireandcabletips.com/what-is-ampacity/

 

[Illinibird]

This was already posted prior and depends on what type of 6-3 you use or go with 4 GA which is a bitch to work with and very expensive. NM-B 6-3 is up to 50 AMPS, but there are two more types of 6-3 that go beyond the 50 AMPS. See prior post so we don't keep posting the same thing.

Sorry I’ll have to find that information. It’s REALLY hard for me to see it but again I’m almost 72 years old VBG ??

 

[Illinibird]

Sorry, I didn't go back far enough to read your initial question. To clarify, it seems that you had the wiring and conduit installed to be rated for a future upgrade to a hardwire connection. This is good future proofing. That being said, a NEMA 14-50 outlet must have a 50 A breaker. If you put a 60 A breaker on it, you're violating code as it's not rated for that. Technically, the Ford charger would only be pulling 32 A even if you put a 60 A breaker, because the NEMA 14-50 is only rated to 40 A continuous max but you can't rely on a well behaved end device, hence the code.

So if you installed 'future proof' wire and conduit rated for 60 A but is currently connected to a NEMA 14-50, then it should be a 50 A GFCI breaker. If you upgrade that in the future to a hardwired connection, at that time you can replace the breaker with a 60 A non-GFCI breaker.

Individual conductors, like THHN are rated for higher current at the equivalent wire size to a Romex (NM-B) wire that doesn't install in conduit. It's all based on temperature rise and an NM-B wire has more insulation. See here: https://www.wireandcabletips.com/what-is-ampacity/

I’d have the outlet removed and Ford Connect hard wired. Now I need to know what 6 gauge wire he used - I think I’ll be alright from that aspect so maybe a go! ?

 

[CHeil402]

Sorry I’ll have to find that information. It’s REALLY hard for me to see it but again I’m almost 72 years old VBG ??

If it's installed in conduit, it's probably copper THHN as NM-B shouldn't be installed in conduit. So if they installed 6 AWG or larger copper THHN, then it is rated for at least 75 A. If that's what's installed, then all you would need to do in the future is to swap out the circuit breaker. If they installed 8 AWG copper THHN, this is only rated to 55 A, so you could not upgrade in the future to a 60 A breaker.

 

[Illinibird]

If it's installed in conduit, it's probably copper THHN as NM-B shouldn't be installed in conduit. So if they installed 6 AWG or larger copper THHN, then it is rated for at least 75 A. If that's what's installed, then all you would need to do in the future is to swap out the circuit breaker. If they installed 8 AWG copper THHN, this is only rated to 55 A, so you could not upgrade in the future to a 60 A breaker.

 

[Illinibird]

Sorry, I didn't go back far enough to read your initial question. To clarify, it seems that you had the wiring and conduit installed to be rated for a future upgrade to a hardwire connection. This is good future proofing. That being said, a NEMA 14-50 outlet must have a 50 A breaker. If you put a 60 A breaker on it, you're violating code as it's not rated for that. Technically, the Ford charger would only be pulling 32 A even if you put a 60 A breaker, because the NEMA 14-50 is only rated to 40 A continuous max but you can't rely on a well behaved end device, hence the code.

So if you installed 'future proof' wire and conduit rated for 60 A but is currently connected to a NEMA 14-50, then it should be a 50 A GFCI breaker. If you upgrade that in the future to a hardwired connection, at that time you can replace the breaker with a 60 A non-GFCI breaker.

Individual conductors, like THHN are rated for higher current at the equivalent wire size to a Romex (NM-B) wire that doesn't install in conduit. It's all based on temperature rise and an NM-B wire has more insulation. See here: https://www.wireandcabletips.com/what-is-ampacity/

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[Illinibird]

If it's installed in conduit, it's probably copper THHN as NM-B shouldn't be installed in conduit. So if they installed 6 AWG or larger copper THHN, then it is rated for at least 75 A. If that's what's installed, then all you would need to do in the future is to swap out the circuit breaker. If they installed 8 AWG copper THHN, this is only rated to 55 A, so you could not upgrade in the future to a 60 A breaker.

?

 

[CHeil402]

... and remember to always seal your conduit properly. Just saw this timely reminder at work today

 

[machefan]

Sorry I’ll have to find that information. It’s REALLY hard for me to see it but again I’m almost 72 years old VBG ??

That's alright, I missed the conduit question too, glad it was answered as well. Sorry ?

 

[Bookworm214]

So the instructions I found online for the JuiceBox 48 recommend against a GFCI saying the JuiceBox meets the GFCI requirement for UL certification. It calls for 4 gauge wire and states that if you're using THHN wire you can use 8 gauge for the ground. So my plan, if I go through with it myself, was to use a 60 amp breaker with the aforementioned wire and conduit for an approximate 40 foot run in my garage to where I currently park.

 

[FPLiptak]

AND....I live in Northern VA too

Are you "Twins sons of different others born in different places at different times?"

 

[machefan]

So the instructions I found online for the JuiceBox 48 recommend against a GFCI saying the JuiceBox meets the GFCI requirement for UL certification. It calls for 4 gauge wire and states that if you're using THHN wire you can use 8 gauge for the ground. So my plan, if I go through with it myself, was to use a 60 amp breaker with the aforementioned wire and conduit for an approximate 40 foot run in my garage to where I currently park.

In the end it's going to have to match what you want to installed. In the case of Ford's charger they recommend GFCI for outlet based and non for hard wired. The faster you charge the more wear and tear on the battery, at least that's how it's been for a while. Will the MACH-E will be different? I would install the fastest charger as possible if it didn't wear the battery down faster. Now speaking of charging, it's been said and over said that one should only charge to 80%, I ask is that still relevant?

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