Install a 40 or 50 amp line for NEMA 14-50 outlet?

[FlatSix911]

For the X with 48A onboard charger what's the benefit of getting the new HPWC vs. getting a NEMA 14-50 done for $350.
Please help me understand. thanks!

Glad to help.
The NEMA 14-50 with the plug-in UMC will charge at 40 Amps maximum.
The HPWC has multiple settings that will allow you to charge at 48 Amps. (Also 12 - 80A)

 

[ssq]

Glad to help.
The NEMA 14-50 with the plug-in UMC will charge at 40 Amps maximum.
The HPWC has multiple settings that will allow you to charge at 48 Amps. (Also 12 - 80A)

View attachment 173824

Thanks, not convinced if it's worth the extra cost to go with the HPWC. I don't do road trips and my daily commute is 40 miles. Of course I agree that I will have to choose between carrying the UMC in the car vs. leaving it in the garage connected to the NEMA14-50. With the HPWC I could have the UMC in the car at all times. The bigger problem could be that while my current main panel allows for NEMA14-50 50A, adding a HPWC may need a new subpanel(?) To gain thr extra 8A (48A vs. 40A) which in turns adds further cost to the project without appreciable gains (X with 48A charger)

 

[FlatSix911]

I would recommend using the supplied 40A UMC and see if you need the additional charging rate of 48 Amps with the HPWC.

Here is Tesla chart comparing charging rates on a Model S. 40A = 29 miles range per hour, 48A = 34 Mph.
The Model X should be a bit lower due to weight... estimated 40A = 25 miles range per hour, 48A = 30 Mph.

 

[DuplexDianne]

I'd only be using the dryer outlet for the short term. I'm pretty sure we need to upgrade our service panel. It's an old Federal Pacific....

Here's the outlet:

 

[TexasEV]

I'd only be using the dryer outlet for the short term. I'm pretty sure we need to upgrade our service panel. It's an old Federal Pacific....

Here's the outlet:

That's a NEMA 10-30 outlet. Tesla no longer makes a 10-30 adapter for the UMC as noted above, but I'm in Austin and have one if you would like to borrow it for a short time while you have your new panel and 14-50 outlet or HPWC installed.

 

[jerry33]

For the X with 48A onboard charger what's the benefit of getting the new HPWC vs. getting a NEMA 14-50 done for $350. Please help me understand. thanks!

The benefit of the HPWC is that it's hardwired into the house which eliminates one connection point (connection points are where problems arise), the cable is longer than the UMC's cable, and, if you install both, you have a backup charging method.

 

[DuplexDianne]

These are all good points to consider. Thank you everyone!

 

[ssq]

The benefit of the HPWC is that it's hardwired into the house which eliminates one connection point (connection points are where problems arise), the cable is longer than the UMC's cable, and, if you install both, you have a backup charging method.

Agreed. But but here's the list of points I have considered:-
- To add a 100A breaker I will have to get new a sub panel ($1100) and then hook it up with the newly bought HPWC($500). The cost of all this adds up to ~ $2k+ including installation.
- My X has a 48A single charger so a HPWC configured at 48A would not give me substantial benefits over 40A NEMA14-50 charging.
- 95% use of the car will be for commute and driving around town < 60 miles any given day.
- I have a supercharger right across the street from work(~15 min/15 miles from home) for any unplanned long trips.
So for now given the combination of single 48A charger + no space in panel - I have arrived at this trade-off decision to go with a NEMA 14-50. I will have the UMC plugged into the wall at all times pretending it to be a HPWC. so that also factors in to the decision. Anyone see any loopholes in this trade-off decision?

 

[FlasherZ]

I will have the UMC plugged into the wall at all times pretending it to be a HPWC. so that also factors in to the decision. Anyone see any loopholes in this trade-off decision?

Nope, plenty of people go this way. If you were buying a new piece of equipment, I'd say to go with WC instead of the UMC. But if you don't mind leaving the UMC out of the car, then not a big deal.

(I carry the cord in the car because I stop at several places where 14-50's exist. The first time I left my UMC at home was an unpleasant surprise.)

 

[jerry33]

Agreed. But but here's the list of points I have considered:-
- To add a 100A breaker I will have to get new a sub panel ($1100) and then hook it up with the newly bought HPWC($500). The cost of all this adds up to ~ $2k+ including installation.

That's correct, however, the HPWC has dip switches so that you can use a breaker size that works for your panel.

 

[ssq]

That's correct, however, the HPWC has dip switches so that you can use a breaker size that works for your panel.

Yes I understand, but given the other factors (48A single charger on the X above all, plus others listed in the post) it would not be of much benefit for me to invest $2000 for 15-20% faster charging. I did consider future proofing the system with a Model 3 reservation in place, but I guess that too could very well be put on another NEMA 14-50 for $150 more for another socket. Could not justify the additional $2000. If I went for the 72A charger on the X, it would be a different story altogether.

 

[TexasEV]

Yes I understand, but given the other factors (48A single charger on the X above all, plus others listed in the post) it would not be of much benefit for me to invest $2000 for 15-20% faster charging. I did consider future proofing the system with a Model 3 reservation in place, but I guess that too could very well be put on another NEMA 14-50 for $150 more for another socket. Could not justify the additional $2000. If I went for the 72A charger on the X, it would be a different story altogether.

No, I don't think you understand. You don't need a 100A circuit to install a HPWC. If you wanted to you could install it on a 50A circuit, just as you would a 14-50, and set it for 40A output. You still have the advantage jerry33 said of it being hardwired and longer cable.

 

[FarmerDave]

No, I don't think you understand. You don't need a 100A circuit to install a HPWC. If you wanted to you could install it on a 50A circuit, just as you would a 14-50, and set it for 40A output. You still have the advantage jerry33 said of it being hardwired and longer cable.

This is exactly what I did. Although my house has 200A service, everything is electric including a 4-ton heat pump and air handler with emergency (resistance) heat. So the electrician could only install a 50A circuit for the Model X.

 

[ssq]

No, I don't think you understand. You don't need a 100A circuit to install a HPWC. If you wanted to you could install it on a 50A circuit, just as you would a 14-50, and set it for 40A output. You still have the advantage jerry33 said of it being hardwired and longer cable.

I follow your and jerry33's points, sorry I was not clear earlier. If you see my previous post with all points on trade-off listed it may make more sense. Let me think this through again, the immediate constraint right now is the wait time on HPWC (5 weeks).

 

[tga]

I'd only be using the dryer outlet for the short term. I'm pretty sure we need to upgrade our service panel. It's an old Federal Pacific....

Here's the outlet:

That's a NEMA 10-30 outlet. Tesla no longer makes a 10-30 adapter for the UMC as noted above, but I'm in Austin and have one if you would like to borrow it for a short time while you have your new panel and 14-50 outlet or HPWC installed.

Using TexasEV's adapter should be safe. If anyone suggests using a 14-50R-to-10-30P adapter with your UMC and 14-50 adapter, don't! While always a bit risky, with your old FPE panel, it could be deadly!

The problem with using these adapters if you have to manually dial down the charge rate to 24 amps (80% of 30) for the 10-30. The car normally remembers the setting based on location, but sometimes it doesn't (after a software upgrade, if it can't get a GPS fix, etc). In that case, it would default to 40A (based on the 14-50 adapter attached to the UMC). Federal-Pacific breakers have a very high failure rate, and can jam on. If both of those happen (bad breaker + reset to full charge rate), you'd be overloading your circuit and the breaker won't trip. Fire is the likely result.

Read FlasherZ's great FAQ, here. He talks about FPE panels.

 

[ssq]

No, I don't think you understand. You don't need a 100A circuit to install a HPWC. If you wanted to you could install it on a 50A circuit, just as you would a 14-50, and set it for 40A output. You still have the advantage jerry33 said of it being hardwired and longer cable.

One more thing I forgot to mention, my main panel with its remaining space and somewhat obsolete breakers cannot accommodate a 60A new breaker which I would need to install a HPWC configured at 48A I am referring to the table below: row 9. The best I can do without adding a new subpanel is 50A breakers. A 50A breaker would give me max 40A output per row 8 in the table for HPWC config.
btw how much max output can a NEMA 14-50 deliver when paired with a 50A breaker. Can the car be configured to take in something like 48A ..without tripping the breaker or does it have to be 90% of breaker max amperage (90* of 50A = 45 A)..? Sorry I am not too familiar with his stuff.

 

[FlasherZ]

One more thing I forgot to mention, my main panel with its remaining space and somewhat obsolete breakers cannot accommodate a 60A new breaker which I would need to install a HPWC configured at 48A I am referring to the table below: row 9. The best I can do without adding a new subpanel is 50A breakers. A 50A breaker would give me max 40A output per row 8 in the table for HPWC config.
btw how much max output can a NEMA 14-50 deliver when paired with a 50A breaker. Can the car be configured to take in something like 48A ..without tripping the breaker or does it have to be 90% of breaker max amperage (90* of 50A = 45 A)..? Sorry I am not too familiar with his stuff.

The maximum EV charging load you are permitted to draw through a 50A circuit would be 40A. This is because a circuit for a continuous load must be sized at 125% of the load. 40A * 1.25 = 50A. The UMC will enforce this as it tells the car only 40A is available when the NEMA 14-50 adapter is attached.

I have personal experience (my own home) with an FPE breaker failing to trip and nearly burning my home down in Northern California. If I hadn't been at home, or even had been in another room for just 15 minutes more, it's likely that we would have had significantly greater damage. The root cause was a bad crimped copper splice clip (similar to a wire nut) used in the 1970's. It failed, melted the insulation on the wire, created arc'ing and a short in the wall, and when the breaker failed to trip the wire melted all of its insulation inside the wall, all the way up the wall.

FPE breakers can be replaced with expensive Connecticut Electric breakers to protect against the trip mechanism problems they experienced, but the Stab-Lok bus design is still pretty weak. That plus the Connecticut breakers are way too expensive. A full panel replacement is going to be a better value over time, IMO, at a significantly lower risk.

As for Zinsco, there are serious issues with the bus designs they used and I don't think twice about strongly recommending their immediate replacement.

 

[K-MTG]

Does insurance still cover these situations without a permit

 

[Bishop]

do you have a jetted tub? mine is labeled spa which is why i ask

 

[DuplexDianne]

The maximum EV charging load you are permitted to draw through a 50A circuit would be 40A. This is because a circuit for a continuous load must be sized at 125% of the load. 40A * 1.25 = 50A. The UMC will enforce this as it tells the car only 40A is available when the NEMA 14-50 adapter is attached.

I have personal experience (my own home) with an FPE breaker failing to trip and nearly burning my home down in Northern California. If I hadn't been at home, or even had been in another room for just 15 minutes more, it's likely that we would have had significantly greater damage. The root cause was a bad crimped copper splice clip (similar to a wire nut) used in the 1970's. It failed, melted the insulation on the wire, created arc'ing and a short in the wall, and when the breaker failed to trip the wire melted all of its insulation inside the wall, all the way up the wall.

FPE breakers can be replaced with expensive Connecticut Electric breakers to protect against the trip mechanism problems they experienced, but the Stab-Lok bus design is still pretty weak. That plus the Connecticut breakers are way too expensive. A full panel replacement is going to be a better value over time, IMO, at a significantly lower risk.

As for Zinsco, there are serious issues with the bus designs they used and I don't think twice about strongly recommending their immediate replacement.

Wow! That's a lot of info. to digest. I'll speak with a couple of licensed electricians and see what they recommend. I'll post their recommendations here to get feedback. Thanks again everyone for taking the time to comment. It's much appreciated!