Jesla or Leviton EVB40-PST

[miimura]

As a suggestion, Tony's company could offer a "pass thru" adapter for their standard equipped 14-50P AC input power cord, with a special resistor value that could be encoded as connected to a 250V, 40A maximum power source and thereby current limit JESLA's output to 32A. That would be a bargain at $50, considering the alternatives! :mrgreen:

You're assuming Tony could divine what that value would be for Tesla's firmware to actually set that pilot signal current. Maybe it's possible, maybe not.

 

[fooljoe]

As a suggestion, Tony's company could offer a "pass thru" adapter for their standard equipped 14-50P AC input power cord, with a special resistor value that could be encoded as connected to a 250V, 40A maximum power source and thereby current limit JESLA's output to 32A. That would be a bargain at $50, considering the alternatives! :mrgreen:

You're assuming Tony could divine what that value would be for Tesla's firmware to actually set that pilot signal current. Maybe it's possible, maybe not.

We've been down this road before in another thread (can't find it now though), and Tony basically said he could do as much and it sounded like such a thing was forthcoming, but I suppose he moved on to more important things (like Jdemo.) It would be really cool if he could make a custom adapter or modify the stock one with a variable resistor of some kind to set the pilot to basically anything you want (at least each of the known settings if the UMC firmware can't handle anything in between.) Those of us "hardcore" types who would actually need or want that feature are probably a pretty slim portion of his customer base, however, so there's probably not much incentive for him to work on it. I assume 90%+ of his customers just plug their Jesla into a 14-50 on the wall and never move it.

 

[Dsinned]

Even if there are only a few customers who want this, it seems like it would be better than telling those customer to upgrade their infrastructure wiring to the full requirements of a 50A outlet. The only motivation to do so is for "future proofing" purposes. Nevertheless, a hard sell with respect to the generally high cost for a whole new wiring install done by a professional with permitting cost to boot.

 

[ppartekim]

It would be really cool if he could make a custom adapter or modify the stock one with a variable resistor of some kind to set the pilot to basically anything you want (at least each of the known settings if the UMC firmware can't handle anything in between.)

Why couldn't someone else here with knowledge make an adapter that does this instead of waiting for Tony to make one? Sounds like Dsinned knows what is needed.

 

[TonyWilliams]

Those of us "hardcore" types who would actually need or want that feature are probably a pretty slim portion of his customer base, however, so there's probably not much incentive for him to work on it. I assume 90%+ of his customers just plug their Jesla into a 14-50 on the wall and never move it.

Well, I'm one of the "hardcore". I'm in negotiation with a manufacturer to make a custom series of plugs, so who knows. Nothing anytime soon, and yes, I'm really busy with other projects.

It would be interesting to know how many just "plug it and forget it" with their JESLA.

 

[kiwiguy]

DISCLAIMER:
This is completely theoretical, I don't know how the adapters work, and don't suggest anyone act on this info!

In theory, and assuming the Jesla wasn't hard coded to only 24 and 40 amps, then 32 amps could be around 17k ohms.
(Geometric mean of 24 and 40 amp values).

Potentially you could put a 36K resistor (or 33K) in parallel with the one in the 24 amp adapter to get close.

 

[ppartekim]

I was just looking at my house wiring and the extra circuit I have available (without out adding more or swapping out) is our old oven circuit. That is a 8ga (8-8-8-8 Alu) w/40A-dp that I could swing over to the front of the garage and throw a outlet on for Level2 Charger.

From what I see above, that means I could only charge at 32A max or 24A if using the Jelsa unless I threw a 50A outlet on it and swapped out the breaker but I would be pushing the 8ga wire pretty hard at its upper limits.

I also thought I saw somewhere that PG&E was giving/waiving some sort of upgrade fee (moving from 200A->400A service) for installing a EVSE system. I need the upgrade anyway if I ever intend to add more solar to my house and to really add a 50A curcuit for the EVSE.

 

[miimura]

I was just looking at my house wiring and the extra circuit I have available (without out adding more or swapping out) is our old oven circuit. That is a 8ga (8-8-8-8 Alu) w/40A-dp that I could swing over to the front of the garage and throw a outlet on for Level2 Charger.

From what I see above, that means I could only charge at 32A max or 24A if using the Jelsa unless I threw a 50A outlet on it and swapped out the breaker but I would be pushing the 8ga wire pretty hard at its upper limits.

I also thought I saw somewhere that PG&E was giving/waiving some sort of upgrade fee (moving from 200A->400A service) for installing a EVSE system. I need the upgrade anyway if I ever intend to add more solar to my house and to really add a 50A curcuit for the EVSE.

8 gauge aluminum is way too small for 50A. You can use 8 gauge copper in conduit, but 6 gauge copper is recommended for Romex at 50A.

The PG&E discounted upgrade is only for the service line between the pole and the meter and only if your service needs to be increased due to EVSE load.

 

[smkettner]

I need the upgrade anyway if I ever intend to add more solar to my house and to really add a 50A curcuit for the EVSE.

I believe you can overdrive 20% on the panel for solar so upgrade would be when solar inverter exceeds 9.6kW.
If you are just out of slots then a subpanel is easily installed. I just cannot imagine any home under 4000 sq ft needs more than 200 amps.

 

[ppartekim]

I need the upgrade anyway if I ever intend to add more solar to my house and to really add a 50A curcuit for the EVSE.

I believe you can overdrive 25% on the panel for solar so upgrade would be when solar inverter exceeds 12kW.
If you are just out of slots then a subpanel is easily installed. I just cannot imagine any home under 4000 sq ft needs more than 200 amps.

That is what I thought too when we upgraded from the 60A to 200A after moving in in 2002. But this being a Silicon Valley home (and built in '49 so still got some knob/tube wiring), I already have 5kW solar up on the roof (and still have a $100/mo bill when averaged out) and two 125A subpanels atached (1 for Solar/spa, 1 for Kitchen/Laundry) to the 200A main. I was told no more solar until I upgrade.

 

[fooljoe]

I don't understand why I keep reading about people upgrading their service due to solar. Solar is a subtractive load. If your house was using up to 100 amps pre-solar, solar would never add to that. Rather, a 5kW system would shave off up to 20 amps of that load!

I could certainly see the need for subpanels if you run out of breaker slots, particularly if you use microinverters, since you can only install so many of those per branch circuit, but there's no reason to upgrade your service due to solar alone, unless you're putting in a truly massive system that can feed back >100 amps on its own (so 25+ kW) if your home isn't consuming any electricity at the time. The whole point of solar is to use less electricity, not more!

 

[Dsinned]

I have a similar limitation in my main service panel on my house (constructed in the late 60s). The main CB is rated at 100A. When I added solar, I could only put 17 - 215W microinverters (each with a 0.9A max. output rating) on my roof, connected to the grid via a 20A CB, without exceeding the 125% maximum overall rating of my service panel. Fortunately, my 4.25kW PV system seems adequate for my year round electricity needs. After my first true up bill (thru March of this year), I actually came out several 100kWhs ahead, somewhat surprisingly. I am charging two EVs (RAV4 and Volt) - although only on average about 1-1/2 times per week - while living in a house with central air (obviously, used a lot during warmers months), fits my power budget quite well.

Question . . . what is the smallest allowable stranded, copper wire AWG (in conduit) that still meets code to string over to a dedicated 50A (NEMA 14-50R) outlet to plug in an L2 EVSE? The outlet is about 40' away from the circuit breaker panel. I think the answer depends on whether the load is continuous or not for longer than 3 hours when energized. Obviously, that would be the case in most situations for a L2 EVSE used to charge a RAV4 EV.

 

[Dsinned]

Fooljoe, I think the national electric code doesn't see it that way! Rather, PV inverters are viewed as potential "loads" on the grid, such as when they may cause a a partial short circuit during an abnormal condition (water intrusion for example). So, for example, my 4.25kW PV system is protected by a 20A circuit breaker. The system's max. output is spec'd to be 240V at 15.3 amps. But, what is this 20A CB actually protecting? The PV system, the grid, or both? Obviously, the NEC says it is protecting both from possible overloads depending on which way the power flows, since the current potentially can flow either way. So, it that 20A is "added" to the other active circuit breakers in the main panel, or no more than 20A + 105A when all are added together. This is 125% allowed even though the full load rating of the panel is actually only 100A max.

 

[fooljoe]

Fooljoe, I think the national electric code doesn't see it that way!

I'd like to see where. As far as I can tell, the NEC is concerned with protecting the bus bars in your panel. 705.12(D)(2) gives options for determining the rating of the bus bars needed. One could choose (a) and make sure the bus bars are sized large enough to accommodate 125% of your solar circuit plus your main breaker (e.g. if the bus bars are rated at 125 amps you could have a 100 amp main breaker and a 20 amp solar circuit.) Or, if one goes to the trouble of relocating breakers so the main and the solar are on opposite ends (b) specifies that 125% of your solar + your main could go up to 120% of the bus bar ampacity (e.g. the same 125 amp bus bars could then accommodate a 40 amp solar circuit (or 2x20 amp.) Or, one could get around all that and get a load analysis done in accordance with (c).

In either case, it's just the bus bars in your panel you need to worry about, so I don't disagree that adding solar could necessitate a panel upgrade (although you might be able to just get away with downsizing your main breaker to accommodate more solar), but that doesn't mean you'd need an associated service upgrade - not by any stretch.

 

[jimbo69ny]

Install 6 gauge copper and forget about it. Sure it might work fine with your 8 gauge but it also might burn your house down and kill your family. To me the extra time and cost of running 6 gauge copper is a no brainer.

 

[smkettner]

I don't understand why I keep reading about people upgrading their service due to solar. Solar is a subtractive load. If your house was using up to 100 amps pre-solar, solar would never add to that. Rather, a 5kW system would shave off up to 20 amps of that load!

I could certainly see the need for subpanels if you run out of breaker slots, particularly if you use microinverters, since you can only install so many of those per branch circuit, but there's no reason to upgrade your service due to solar alone, unless you're putting in a truly massive system that can feed back >100 amps on its own (so 25+ kW) if your home isn't consuming any electricity at the time. The whole point of solar is to use less electricity, not more!

Solar adds to the potential load. If you have a 100 amp panel and 25 amps of solar coming in then you potentially can use 125 amps of power in the home before the 100a breaker trips. The bus is only rated 100 amps. NEC allows the additional 20% I assume because the power (load) is generally spread across the bus. This is why solar is attached at the bottom of the stack away from the main breaker.

 

[fooljoe]

Solar adds to the potential load. If you have a 100 amp panel and 25 amps of solar coming in then you potentially can use 125 amps of power in the home before the 100a breaker trips. The bus is only rated 100 amps. NEC allows the additional 25% I assume because the power (load) is generally spread across the bus. This is why solar is attached at the bottom of the stack away from the main breaker.

20%, not 25%. Again, I don't disagree that a panel upgrade might be needed, but what I'm objecting to is the idea that a service upgrade might be needed (i.e. the feeder from utility to panel), which is what ppartekim brought up. Solar could add to the load on your panel's bus bars, but it won't add to your home's overall load from the utility.

 

[smkettner]

I suppose you could upgrade the main panel rating and not increase the main breaker size.

 

[fromport]

Question . . . what is the smallest allowable stranded, copper wire AWG (in conduit) that still meets code to string over to a dedicated 50A (NEMA 14-50R) outlet to plug in an L2 EVSE? The outlet is about 40' away from the circuit breaker panel. I think the answer depends on whether the load is continuous or not for longer than 3 hours when energized. Obviously, that would be the case in most situations for a L2 EVSE used to charge a RAV4 EV.

50ft run or less
#6 40 amp

source: https://www.icmag.com/modules/Tutorials/ElectricalSafety/1655.htm

 

[rickrides]

DISCLAIMER:
This is completely theoretical, I don't know how the adapters work, and don't suggest anyone act on this info!

In theory, and assuming the Jesla wasn't hard coded to only 24 and 40 amps, then 32 amps could be around 17k ohms.
(Geometric mean of 24 and 40 amp values).

Potentially you could put a 36K resistor (or 33K) in parallel with the one in the 24 amp adapter to get close.

I was thinking of wiring a 160k resister in parallel with the 140k in my 5-15 adaptor so I could use it on a 20 amp outlet. But I see no practical way of doing that without cutting open a $50 adaptor...Not worth it.

BTW I took my Jesla to the rally in Cupertino yesterday. Didn't need it...92 miles round trip.