HPWC Install Requirements for my panel

If installing directly below the panel you're showing here, likely on the order of $300-400ish if you're staying really close to that panel and don't mind surface-mounted conduit. The biggest challenge you'll have is that you'll have to mind bend radius while keeping pullboxes (like an LB) accessible. It will also depend on how neat you want it to be. If you want to keep conduit inside the wall, it'll cost more than if you use flex conduit coming out the bottom of the panel, routed on the surface to the left side of a surface-mounted HPWC next to the panel. That way you can use LB's because their pull-covers will still be accessible.

(Assuming 100A install with #3 which will require conduit, as opposed to using NM-B in-wall for a 50A install.)

The bend in the wires is the tough part... 100 A circuit requires some pretty thick copper. I actually had mine installed on the inside wall, directly opposite the main breaker box coming into the house. No need to run long wires. tapped into one of the 100a lines of the 200a coming to the house. Since we charge late at night, no issue on sharing the power with any other usage.

rickgt said:

The bend in the wires is the tough part... 100 A circuit requires some pretty thick copper. I actually had mine installed on the inside wall, directly opposite the main breaker box coming into the house. No need to run long wires. tapped into one of the 100a lines of the 200a coming to the house. Since we charge late at night, no issue on sharing the power with any other usage.

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You live in CA, where the service disconnect and main breaker is generally (not always) located outside, and the connection that goes into the panel inside the home is fused. That's not true of most of the US. It's likely that the service entrance you see at the bottom of the OP's panel is unfused from the bottom of the meter, which means you can't tap there without it being a dangerous situation.

(Also, if you have a 200A panel, you don't have 2 100A lines... you have 2 hot legs capable of carrying 200A each. That doesn't mean you have 400A, it just means you have 200a because return current goes over the other leg for 240V loads.)

FYI, this was a $300 install for me which included the 100A breaker, wire and labor:

Take a look in the Florida section at this thread: Electrician-in-Tampa-Bay and there's other recommendations if you do a search for "electrician" in that section. My guess is that in this area you'll be looking at <$400 as the run is very short.

You might also consider joining the Florida group Florida-Tesla-Enthusiasts-(FTE)-club-sign-up-page so that you could talk to a few folks in Tampa directly if needed.

Tampaukfan said:

Thanks for the replies! NOLA_Mike, is your panel 200amp?

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Actually, that is a 125A subpanel. My main is outside and I have 225A service into the house.

I was able to put in the 100A breaker for the HPWC because I have a 30A breaker for my dryer that is unused (I have natural gas dryer) and a 30A breaker for a cooktop that is unused (natural gas cooktop). In addition I have natural gas hot water heaters and natural gas central forced air furnaces.

They took out the 30A cooktop breaker and replaced it with the 100A for the HPWC.

I just installed a HPWC three feet from the same panel that you have and a NIMA 14-50 plug. Cost $480. That included #3 wire in a conduit above the sheet rock with the HPWC about 3ft to the left of the panel. I mounted a NIMA 14-50 plug just below the panel. While the electrician was installing the HPWC I realized there is a fair amount of electronics in the HPWC that I thought a back up solution would be worth while. So I went to Home Depot got #6 wire, a 50A breaker and a NIMA 14-50 plug and he installed it.

Its a very simple installation. What is hard is dealing with the wire which is stiff because of its size. I know I could have done it but would have taken me four times the amount of time of the electrician.

Why did you need a 100 amp breaker!? Even if you have dual chargers (which I don't think is necessary for overnight charging) that's only 80 amps, right?

I just posted a similar question. I've got a 150 amp service and already have a Volt charger (2-pole 20 amp) and was concerned about the additional 40-amp breaker for the HPWC . . .

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From Tesla's site:

Note that Model S must be equipped with the Dual Chargers option to accept charge currents above 40 amps (50 amp circuit breaker).

It is my understanding that the breaker needs to be 20% larger in rated amperage than your expected amperage draw. That is why the 100 AMP breaker for the 80 AMP draw. The 100 AMP breaker is not an inexpensive item. Your service panel is flush mounted so you will probably want to maintain that look and have the conduit mounted behind the wallboard. Nice Project.

Breakers need to be a step or two ABOVE the usage. @pan needs a 60A ahead of his 14-50 outlet for example! With the Tesla HPWC serving a dual-charger ModelS the breaker needs to be 100A (or maybe 90A if you can find one).
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wycolo said:

Breakers need to be a step or two ABOVE the usage. @pan needs a 60A ahead of his 14-50 outlet for example! With the Tesla HPWC serving a dual-charger ModelS the breaker needs to be 100A (or maybe 90A if you can find one).
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This is true in the vast majority of installations, but is not true "always"; the code does allow for breakers that are rated for 100% continuous load. For example, the breakers used in Tesla's Superchargers are rated at 100% continuous load and are sized that way.

That being said, I don't know of any breakers available for home sized panels that are 100% continuous rated. For all installs that we are likely to see in our houses, the breaker must be sized at 125% of the continuous load, or stated another way, the continuous load must be no more than 80% of the breaker size.

90 Amp breakers were a choice for the original HPWC's which could be set to 72 Amp charging, but that choice is not available on HPWC's being shipped now.

wycolo said:

Breakers need to be a step or two ABOVE the usage. @pan needs a 60A ahead of his 14-50 outlet for example! With the Tesla HPWC serving a dual-charger ModelS the breaker needs to be 100A (or maybe 90A if you can find one).
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This is incorrect... they don't have to be and in some cases, shouldn't, depending on the load.

A 60A breaker on a NEMA 14-50 receptacle is an illegal install. A 50A breaker on a 50A intermittent load on a 14-50 receptacle is just fine.

The conductors and breakers must be sized for 125% of the offered continuous load + intermittent load. So on a 40A charging current, you must size the circuit conductors and breaker for 50A. For an 80A charging current, you must size the circuit conductors and breaker for 100A.

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ArtInCT said:

It is my understanding that the breaker needs to be 20% larger in rated amperage than your expected amperage draw. That is why the 100 AMP breaker for the 80 AMP draw. The 100 AMP breaker is not an inexpensive item. Your service panel is flush mounted so you will probably want to maintain that look and have the conduit mounted behind the wallboard. Nice Project.

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Just to clarify - for continuous loads (EV charging is ALWAYS a continuous load), the breaker must be sized at 125% of the charging load - hence 80A charging load means 100A circuit size (conductor + breaker rating). Don't forget that it's not just about breaker size - the conductors/wiring must accommodate that load, too. I can recall (from my childhood) a relative of mine melting his wiring when, after blowing a 15A fuse in one of the old fuse panels, he decided that it shouldn't blow the fuse anymore and replacing it with a 30A fuse. It doesn't work that way.

Thread hijack .... Tesla's recommended installer visited yesterday. I have 400 amp service, 2 200 amp panels. He told me (assuming I understood) that code requires any device > 50 amps be on its own sub panel. So, my choice was either 1) install my HPWC on a 50 amp circuit or 2) have a 3rd panel run - from the meter, thru my brick wall, then to a new 150 amp panel, then to the HPWC.
A 50 amp hookup clearly isn't bad, and I will almost never need anything more; if it saves me > $2000 then is worth it, but not what I was hoping to hear.

2nd opinion coming Monday 730 AM.

PS the HPWC which arrived yesterday looks a little different that I've seen previously posted. Part number 1008488-00-D

CSFTN said:

Thread hijack .... Tesla's recommended installer visited yesterday. I have 400 amp service, 2 200 amp panels. He told me (assuming I understood) that code requires any device > 50 amps be on its own sub panel. So, my choice was either 1) install my HPWC on a 50 amp circuit or 2) have a 3rd panel run - from the meter, thru my brick wall, then to a new 150 amp panel, then to the HPWC.
A 50 amp hookup clearly isn't bad, and I will almost never need anything more; if it saves me > $2000 then is worth it, but not what I was hoping to hear.

2nd opinion coming Monday 730 AM.

PS the HPWC which arrived yesterday looks a little different that I've seen previously posted. Part number 1008488-00-D

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I've never heard of this requirement. Sounds like BS. Perhaps he meant that it needed a cutoff switch which can be a breaker near the HPWC. Some localities require this. But a dedicated panel? Uh, no.

CSFTN said:

Thread hijack .... Tesla's recommended installer visited yesterday. I have 400 amp service, 2 200 amp panels. He told me (assuming I understood) that code requires any device > 50 amps be on its own sub panel. So, my choice was either 1) install my HPWC on a 50 amp circuit or 2) have a 3rd panel run - from the meter, thru my brick wall, then to a new 150 amp panel, then to the HPWC.
A 50 amp hookup clearly isn't bad, and I will almost never need anything more; if it saves me > $2000 then is worth it, but not what I was hoping to hear.

2nd opinion coming Monday 730 AM.

PS the HPWC which arrived yesterday looks a little different that I've seen previously posted. Part number 1008488-00-D

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Unless it's some weird local rule, this is not the case. I know plenty of HPWC installs on 100A breakers that are on a standard service panel. Perhaps he looked at your 200A panels and found that the load calculations didn't work out, and was suggesting a new panel for it. Let's see what Monday brings.

Monday's electrician disagreed. There's room in my current panel for a 50 amp breaker and its load. Too much on it for a 100 amp load. But, if I replace my ceiling lights with LEDs, I will have enough spare amps to run a 100 amp circuit. For now, I will go with the 50 amp circuit, HPWC set for 40 amp function, but wire for 100 amps. I think.
Yes, I have a lot of 6 inch 120 W ceiling lights. About 70.

CSFTN said:

Monday's electrician disagreed. There's room in my current panel for a 50 amp breaker and its load. Too much on it for a 100 amp load. But, if I replace my ceiling lights with LEDs, I will have enough spare amps to run a 100 amp circuit. For now, I will go with the 50 amp circuit, HPWC set for 40 amp function, but wire for 100 amps. I think.
Yes, I have a lot of 6 inch 120 W ceiling lights. About 70.

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You should switch to LEDs anyway and save yourself some cash.