(moderator note - split off from another thread on minimum amps needed)
If one had to upgrade, why not consider going to a 400 amp service
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Why not install 400amp service instead of 200 when upgrading?
- Thread starter h2ofun
- Start date
The same size underground conduit is required by PG&E for a 200A service and a 400A service (320A continuous, called CL320), namely 3". And the main expense is in the underground conduit installation, so if upgrading from 200A to 400A were required in the future, the expense should be much less.
The NEC load calc is very conservative, so if it's under 200A, then installing 400A equipment would just be a waste of money and space.
But sure, if it's borderline, or if you anticipate adding loads in the near term that will push the load calc above 200A, go ahead and install a 400A service. Assuming PG&E doesn't have a requirement for you to demonstrate up front that 200A is insufficient, not sure about that.
Cheers, Wayne
Why would you really need a 400a service on a residential house? I have a 4700sq ft house on a 200a service with 3cac, 3 fridges/freezers, pool, pond, wine cellar, full work shop and over 150 can lights and my usage has never gone over 12kWh (and that was a high usage hour where it was 100 degrees out and my wife put the electric dryer on normally I am around 2kWh to 6kWh in the summer and 1.3-1.6kWh in the winter). I do have 2 sub panels because of the number of circuits but the electrical inspector said I was no where near the usage to require upping over 200a.
Especially in California with a plan to install solar and batteries.
I upgraded my service last year and went all the way to 400A. Remember that service upgrades must always comply with current rules while like for like replacements can be done at any time. All of what you said only applies if PG&E does not change the green book. In theory, they could change the rules to require a larger conduit for 400A (or larger conduits for both) and then you are stuck paying for trenching again if you ever need more than 200A, whereas if you go all the way to 400A now, it doesn't matter what changes they make to the green book because that specific service line is grandfathered as a 400A service line. This was my only motivation for going to 400A -- I don't really need it right now but I definitely don't want to risk ever having to shell out money for trenching again.
I have a 400 amp service, 3300 sq ft home. What is your heating? Mine is 100% heat pump. Again, its not the need, it is if one is going to spend crazy money for a 200, why not ask what extra cost to go 400! I blew it on my batteries, but did it right on my extra panels.
You were so smart. Some are just so short sighted. How many come on here and say they wish they have put on more solar or more batteries.
This is why if I do wire my garage for EV charging, going to see what the cost is to do 5 spots. 5 spots, at the maximum allowed J1772 current of 80A, is 400A continuous, just for the garage. Not even "400A" service (i.e. CL320 or 320A continuous) would allow that, and that leaves you 0A for everything else. That's the other part of the reason I went with 400A: I'm aware that J1772 allows up to 80A per vehicle and at that charging rate, just 2 spaces consumes 160A which basically leaves you only 40A for the rest of your house. Just because Tesla isn't installing 80A OBCs in their vehicles now (other than a few early Model S vehicles with that option) doesn't mean they won't ever do so. And Lucid and some other brands are installing 80A OBCs.You were so smart. Some are just so short sighted. How many come on here and say they wish they have put on more solar or more batteries.
No, yep, it would not work, let alone, not sure I could get coded.
The tesla charger allows sharing. So I would like to, if possible, drive a 200 amp subpanel in my garage. They hook up the tesla smart charger. Today, they work with 4, but the spec is much more. I would put in 60 amp breakers per charger, again assuming I can get coded. So far, no one has bitten. When I have told them I want a permit, they never get back to me
ucmndd
Well-Known Member
Exactly, the flexibility to charge at up to 80 amps from any of 5 locations is not remotely the same use case as charging 5 vehicles at 80 amps simultaneously. I’d assume a rational load calculation and/or load sharing protocol among the EVSEs would address this sufficiently.
Yeah, in a practical sense, I can't see a need to charge 5 vehicles at 80A simultaneously at a private residence. So sharing I think makes sense when going with 3+ vehicles. But I could see a household needing to charge 2 vehicles at the maximum 80A rate simultaneously and by going with only 200A service, you kind of back yourself into a corner. If you've got the pool pump and AC running at the same time or you're using 2 major kitchen appliances while doing that, you'd trip your main 200A breaker. I could see upgrading only to a 200A panel right now if your service line comes in overhead but if it's underground and trenching costs are involved I just don't think it makes sense to even risk PG&E making changes to the green book. Going with 400A service was maybe an extra $2-3k for a bigger main panel and a 200A subpanel for the house circuits, and this avoids the possibility of having to pay another $7-10k for trenching again plus having to rip out the old main panel and upgrade it in the future.
I am partially heat pump and nat gas/ hydronic. But even if I was all heat pump it wouldn't change load calcs because it would be no different than me running my ACs in the summer. I find the electric dryer uses a shocking amount of electricity.
Around here it is not expensive to go from 100 to a 200amp service. The last time I did it it was around $2k.
I see a lot of talk is based on electric cars and the fact that it seems we are fully heading there in the near future. I don't see the need for most people to go much larger than a 32a charger on a 40amp circuit. A 100kWh battery will charge in around 10-11 hours at that rate. For a home that's not unreasonable for something most people will need to do once or twice a week. Very high charge rates are more important when comparing on the go recharges to get as close to gas station times as possible.
It obviously works for you but not everyone is is your shoes or wants to be in your shoes when the $8 per kW fixed charge comes along. I prefer needs based analysis.
My dryer only uses 23A, which is not that much. Dryers are always on a 30A circuit and thus capped at 24A.
It's cheap if your service line drop comes in overhead from a power pole. It's expensive if it's underground and requires trenching. If you have an overhead service drop, then you are lucky, and can simply get whatever size panel you need now and upgrade further in the future if necessary. If you have to trench, then I recommend just going to 400A to avoid the risk that PG&E changes the rules and requires you to pay for another trench and conduit replacement.
Very high charge rates are nice to reduce overhead, although not necessary most of the time. These cars consume about 400W just to run the computers and so the faster you can charge the batteries, the less (percentage wise) goes to overhead and the more goes into the battery.
If it was the 80 percent rule it would be 320 Amps. In my mind it is not nonsense, it is safety.
SalisburySam
Active Member
TL;DR - upgraded to 400 amps to the house as part of re-wiring the property. Likely don’t need that much but feel we’re future-proofed here for anything we might wish to do in the home.
Detailed version -
Moved into our 1906 historic home with about 4700 sq ft on two floors that had very poorly-done wiring (e.g. ground wire was just hanging in the crawl space not connected to anything) and a telephone pole supported overhead supply lines in the middle of the back yard. We knew we had to make this all safer and wanted the pole gone. So at not insignificant expense we had an underground line trenched from the power pole on the corner of our lot to the service entrance on the side of the house. We had an odd service entrance as the home was three separate apartments at one time and we consolidated everything into one. We originally had 200 amps coming in but since we were trenching anyway upgrading to 400 amps was at marginal cost, and we did that. The 400 is broken into two 200-amp panels, with 100 amps from one of the panels going to the detached garage. And the electrician properly grounded the new installation for which we were very thankful.
Will we ever need 400 amps? I don’t know, but probably not. We replaced the two aged HVAC units with very high efficiency ones, replaced the 65 outside halogen landscape lights with LEDs, replaced every single bulb in the house with LEDs, and no major appliance is over 5 years old. With our historic status, the home will never be allowed to have solar panels either in the yard or on the roof so any alternate power source would at best be a standby generator. For us, the question wasn’t so much do we need 400 but more of why not 400 for the slight additional cost.
One pleasant surprise out of this: the power company (Duke Energy) replaced the transformer supplying us and two other homes to accommodate the larger amperage to our home. Supposedly that was about a $25k upgrade for Duke, and we have a new transformer. I’m sure all Duke subscribers, including us, saw a rate increase for that but at least we didn’t have to pay it all.
Detailed version -
Moved into our 1906 historic home with about 4700 sq ft on two floors that had very poorly-done wiring (e.g. ground wire was just hanging in the crawl space not connected to anything) and a telephone pole supported overhead supply lines in the middle of the back yard. We knew we had to make this all safer and wanted the pole gone. So at not insignificant expense we had an underground line trenched from the power pole on the corner of our lot to the service entrance on the side of the house. We had an odd service entrance as the home was three separate apartments at one time and we consolidated everything into one. We originally had 200 amps coming in but since we were trenching anyway upgrading to 400 amps was at marginal cost, and we did that. The 400 is broken into two 200-amp panels, with 100 amps from one of the panels going to the detached garage. And the electrician properly grounded the new installation for which we were very thankful.
Will we ever need 400 amps? I don’t know, but probably not. We replaced the two aged HVAC units with very high efficiency ones, replaced the 65 outside halogen landscape lights with LEDs, replaced every single bulb in the house with LEDs, and no major appliance is over 5 years old. With our historic status, the home will never be allowed to have solar panels either in the yard or on the roof so any alternate power source would at best be a standby generator. For us, the question wasn’t so much do we need 400 but more of why not 400 for the slight additional cost.
One pleasant surprise out of this: the power company (Duke Energy) replaced the transformer supplying us and two other homes to accommodate the larger amperage to our home. Supposedly that was about a $25k upgrade for Duke, and we have a new transformer. I’m sure all Duke subscribers, including us, saw a rate increase for that but at least we didn’t have to pay it all.
Dryers are not continuous loads, so there would be nothing wrong with 7.2 kW (30A) dryer, but I don't know that any such electric dryers exist.
Cheers, Wayne
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