Choosing between 32a plug-in and 48a hardwired

[joebruin77]

Good advice.
In my case, I have a 100A sub panel in my garage, so I hardwired my Ford Connected Charge Station and installed a separate 14-50 receptacle outlet in case in need to use the Mobile Charger. Maximum flexibility.

I did something similar. I have a 48-amp Tesla Wall Connector and a separate 14-50 outlet, which of course can put out a maximum of 40-amps. For anyone who has a hard-wired EVSE, I highly recommend having a separate 14-50 outlet installed as well. If you ever have a problem with the EVSE, it is super convenient to have that 14-50 outlet there which you can temporarily rely on until the EVSE is either repaired or replaced.

This is my second Tesla Wall Connector. The first one went "kafluey" and was replaced under warranty by Tesla. But it took about 4 weeks until the unit was replaced by my electrician. During that time, I had to make due with a 120 outlet and public level-2 EVSE's. This taught me the value of having a separate 14-50 outlet as a backup.

And when comparing costs, don't forget to get check with your local utility for rebates. My local power company offers a $500 rebate, but only if the EVSE is hard-wired. It will not offer any rebates for a 14-50 outlet or an EVSE that is plugged into a 14-50 outlet.

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[Snowrider69]

I have the ChargePoint Home Flex, NEMA 14-50 plug-in and been using it for the last 18 months for my MME.... been great. I chose the plug-in since it allows me the flexibility to use the mobile charger if something happens to my CP. If it needs replacing., unplug the old plug in the new. I believe that it only provides 40 amps on the 50 amp circuit, but it's been more than enough to charge over night.

 

[dtbaker61]

Rather than harp on you using the mobile charger for your daily ...

You said a 32A EVSE requires a 50A breaker. That's not right. You need a 40A breaker. You basically need about 20% overhead. So a 50A service will support a 40A EVSE. A 60A hardwire solution will support up to a 48A EVSE.

In my opinion, put in a NEMA 14-50 socket. It will give you flexibility, and also allow you to take the EVSE with you should you ever move, or easily replace it should it fail. Even at less amperage, it only costs slightly more time to charge. If you're charging up overnight anyway, the amperage really doesn't matter much.

But please don't stick to using the mobile charger. You're just going to end up disappointed. Check with your power utility to see if they offer discounts on EVSEs. Mine offered a $500 INSTANT rebate, making the JuiceBox 40 about $150 out of pocket.

I beg to differ.

If you put in a NEMA 14-50 receptacle, the 50 there at the end is what tells you you *should* have a 50amp breaker and use 6awg wire with 8awg ground for generic use. For charging an EV however, you do NOT want to run more than 32amps since a charge can take more than 3 hours, which de-rates the circuit.

I wanted an outlet rather than hardwire because I don't need any more than 32amps to charge overnight, AND I wanted a 240v outlet available to backfeed 'emergency generator' power when the grid is down. My 'emergency generator' happens to be my MME

The only disappointing thing about my mobile charger was how flimsy the 'lock trigger' was, which broke off.... Dealer got me a new one under warranty, and it's been used almost every day with no disappointments.

 

[Fat Mach]

oohhhhh, if your house service is 100a, you really should consider electrical upgrade to 200a.... and if you consider adding Solar to your house, the upgrade may be done as part of the required prep for Solar and eligible for combining with cost of Solar for Federal Tax Credit. (26% this year, but dropping to 22% next year).

nice way to get a double win for work you need to do any way.... save money, and generate clean electricity for your MME to boot.

My house has what I think is a 200A main panel since I have a large Solar City panel system. I bought the house with the system... Don't feel too bad for me, I cancelled my first offer and reduced it by $40k when I found out about the lease- and they accepted the revised offer. Free solar!!!

Anyway, I have an ADU that's fed with a 70A breaker off my main panel. Would it be as simple as I'm envisioning to add a 300 or 400A main panel, then make each of my existing panels sub panels of it? I'm in a rural area and actually have my own power pole on my property that feeds the existing main panel about 10 feet away.

My concern is running two AC units, potentially two ovens, two dryers, a 48A Emporia charger, etc off the 200A panel.

 

[dtbaker61]

My house has what I think is a 200A main panel since I have a large Solar City panel system. I bought the house with the system... Don't feel too bad for me, I cancelled my first offer and reduced it by $40k when I found out about the lease- and they accepted the revised offer. Free solar!!!

Anyway, I have an ADU that's fed with a 70A breaker off my main panel. Would it be as simple as I'm envisioning to add a 300 or 400A main panel, then make each of my existing panels sub panels of it? I'm in a rural area and actually have my own power pole on my property that feeds the existing main panel about 10 feet away.

My concern is running two AC units, potentially two ovens, two dryers, a 48A Emporia charger, etc off the 200A panel.

most likely you can run your main house and ADU with your existing 200a service. you might have to add a sub-panel and tandem a few branch circuits to make room for a 100amp subpanel to ADU

stepping up to 300a+ service is a big deal, and likely to cost $5k-$10k because extra engineering reviews, permits, and likely new conductors on the utility side are required... assuming your nearest transfer and line can support the added capacity

stick with your 200a service if possible! add subpanels if you can.....

 

[eBullitt]

For charging an EV however, you do NOT want to run more than 32amps since a charge can take more than 3 hours, which de-rates the circuit.

This is a valuable discussion for me since I will supposedly be taking delivery of my MME in weeks instead of months! I have a NEMA 14-50 with 50 amp breaker installed at home. Based upon my needs, my original home charging plan was to use the Ford mobile charger as my primary EVSE. Reading the many posts about failures associated with the Ford mobile charger has caused me to reconsider that plan and think about purchasing a 40 amp EVSE such as Chargepoint Flex or Juicebox 40. Everything I've read about these EVSE's indicated that either device matched with the NEMA 14-50 outlet was a reliable option. Not being an electrician, I have never heard of "de-rating" a circuit," before. which sounds like degradation of some sort. Is this something others have noticed or have concerns when using a 40 amp EVSE paired with a NEMA 14-50 outlet?

 

[Maquis]

most likely you can run your main house and ADU with your existing 200a service. you might have to add a sub-panel and tandem a few branch circuits to make room for a 100amp subpanel to ADU

stepping up to 300a+ service is a big deal, and likely to cost $5k-$10k because extra engineering reviews, permits, and likely new conductors on the utility side are required... assuming your nearest transfer and line can support the added capacity

stick with your 200a service if possible! add subpanels if you can.....

Since he says he’s in a rural area, there are probably no permits or inspection involved. That’s how it is here. However, the utility likely won’t let you upgrade the service to 320 without justification such as a new load calculation showing that what you are adding necessitates upsizing.
I agree with you, his 200 is likely adequate.

 

[Maquis]

This is a valuable discussion for me since I will supposedly be taking delivery of my MME in weeks instead of months! I have a NEMA 14-50 with 50 amp breaker installed at home. Based upon my needs, my original home charging plan was to use the Ford mobile charger as my primary EVSE. Reading the many posts about failures associated with the Ford mobile charger has caused me to reconsider that plan and think about purchasing a 40 amp EVSE such as Chargepoint Flex or Juicebox 40. Everything I've read about these EVSE's indicated that either device matched with the NEMA 14-50 outlet was a reliable option. Not being an electrician, I have never heard of "de-rating" a circuit," before. which sounds like degradation of some sort. Is this something others have noticed or have concerns when using a 40 amp EVSE paired with a NEMA 14-50 outlet?

There have been reports of melting receptacles. Avoid the $10 Leviton sold at the big box stores. Have your electrician get an industrial rated receptacle from his supply house.

The “derating” simply means you can only use a branch circuit at 80% of its rating when the load is continuous (which an EVSE is). Thus 40A EVSE on a 50A circuit.

 

[dtbaker61]

This is a valuable discussion for me since I will supposedly be taking delivery of my MME in weeks instead of months! I have a NEMA 14-50 with 50 amp breaker installed at home. Based upon my needs, my original home charging plan was to use the Ford mobile charger as my primary EVSE. Reading the many posts about failures associated with the Ford mobile charger has caused me to reconsider that plan and think about purchasing a 40 amp EVSE such as Chargepoint Flex or Juicebox 40. Everything I've read about these EVSE's indicated that either device matched with the NEMA 14-50 outlet was a reliable option. Not being an electrician, I have never heard of "de-rating" a circuit," before. which sounds like degradation of some sort. Is this something others have noticed or have concerns when using a 40 amp EVSE paired with a NEMA 14-50 outlet?

max current rating for a 14-50 outlet/plug is 50 amps (protected with a 50 amp breaker because a couple minutes of use above 50 amps heats up and trips the breaker)

car charging typically runs at full load for 3+ hours, and builds up heat, particularly in molded plugs that don't have any air flow to help dissipate heat. If you really dig into the issue, you will find that a circuit rated for 50amps at 70F for an hour *should* be de-rated when you are running for 3+ hours, possibly starting in 90F ambient temps. you might be fine at 38amps, safer at 36amps, and safe at 32a up to ambient temps over 100F

thus using the 32a mobile charger is fine under just about any conditions.
I don't have any idea what the failure rate of the mobiles has been since we don't know how many people use them on a daily basis. I have... and have had no problems using since 3/2021

I.m just offering facts about chargers/plugs for your consideration.... not opinions based on whether the mobile charger is reliable or not.

 

[BalsaDust]

Just my opinion and I usually speak out of my a$$ anyway, but a dedicated EVSE in the garage set at 32amps so as not to over tax the home or the car (Grizzle-e std) and keep the "Mobile" charger in the car for emergencies.

Ford list it as a "Mobile" charger and thats what I consider it.

Tony

 

[JohnFoxeSheets]

oohhhhh, if your house service is 100a, you really should consider electrical upgrade to 200a.... and if you consider adding Solar to your house, the upgrade may be done as part of the required prep for Solar and eligible for combining with cost of Solar for Federal Tax Credit. (26% this year, but dropping to 22% next year).

nice way to get a double win for work you need to do any way.... save money, and generate clean electricity for your MME to boot.

Good idea about bundling in the panel upgrade, but sadly that ship has sailed; we already have solar. We looked into upgrading the panel but there is a long line of cascading challenges that would make the upgrade take several months and cost several thousand $$ and we're doing fine on our 100A service... But anyway, happily we've been gathering electrons from the sun since 2015, and when we installed PV solar we maxed out the panels on our roof since we planned for an eventual EV.

 

[Mauser]

My 100A house panel envies your 100A garage sub panel

I'm in the same boat. Had several electricians in to quote running the necessary kit to my garage. I found out, because I have only 100A service to the house, they need to install an interlocker which monitors total house draw before allowing the connection to the garage. This interlocker itself is $1,600 CAD alone, with the total cost of the install being over $4000 CAD.

Fat sad incoming...

 

[Davedough]

I was lucky that the house I moved into had a full 100A subpanel that was mostly open. I hardwired my ChargePoint Flex. I see about 43mph @ 11kW charge rate set at 48A. The unit cost me $700, but comes with a 14-50 dongle if you want to plug it in and step down the current. The install only cost me $250 in this house because I mounted the EVSE about a foot from the panel.

 

[Blue highway]

max current rating for a 14-50 outlet/plug is 50 amps (protected with a 50 amp breaker because a couple minutes of use above 50 amps heats up and trips the breaker)

car charging typically runs at full load for 3+ hours, and builds up heat, particularly in molded plugs that don't have any air flow to help dissipate heat. If you really dig into the issue, you will find that a circuit rated for 50amps at 70F for an hour *should* be de-rated when you are running for 3+ hours, possibly starting in 90F ambient temps. you might be fine at 38amps, safer at 36amps, and safe at 32a up to ambient temps over 100F

thus using the 32a mobile charger is fine under just about any conditions.
I don't have any idea what the failure rate of the mobiles has been since we don't know how many people use them on a daily basis. I have... and have had no problems using since 3/2021

I.m just offering facts about chargers/plugs for your consideration.... not opinions based on whether the mobile charger is reliable or not.

+1 on this. I ran my Grizzle charger at 40A for about a year, but in summer months it can be 100F here. When that happens, the plug going into the 14-50 outlet, and the plug going into the car got warmer than I'd like after a couple of hours.

I turned the Grizzle charger down to 32A and it is much cooler both where the cable goes into the car and at the 14-50 outlet.

Small increase in charging time, (which has no practical impact because it charges at night) but it has a significant reduction in heat going down from 40A to 32A

 

[dmastro]

Why is this a question? If you're going to buy a $50K - $60K+ vehicle, why wouldn't you plan to also install a proper wall charger? They're not very expensive and many utility companies provide rebates which cover a good portion of the cost.

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