400 Amp service upgrade

ylmzmJune 3, 2013

We bought an old house (~2500 sqft + 2 car garage) and started upgrading it. The house had an oil furnace and not much appliance. We removed the oil furnace and plan to install a micro-split ductless HVAC system. The house is all-electric.

The following is the list of items (most of them will be installed as soon as service upgrade is completed)
- 1 Outdoor heat pump (4 ton, 9.5kW)
- 3 indoor heat exchangers, each 1.5 ton, 3kW
- 1 double wall oven, 9.5kW
- 1 electric cooktop, 12kW
- Dryer, 7.2kW
- Washing machine, 1.5kW
- Dishwasher, 1.5kW
- Couple of other small appliances, 2kW
- 2 fridges, each ~ 1.5kW
- Water heater, 4.5kW

In garage:
- Lots of power equipment, though not all running at the same time: welder (60 Amp), compressor (30 Amp), miter saw, and other tools.

And outdoor lighting. There are also 3 bathrooms if that makes any difference.

And in the next few years:
- The house will be repiped. We may add tankless water heaters, and if we do, we may need two 18kW units.
- We may add two EV car charging stations.
- We may add solar panels.
- Expand the house (+1000 sqft)

We live in San Francisco bay area and PGE is the utility company. We will ask for a service upgrade anyway, but I am not sure whether it should be 200 Amp or 400 Amp (we have 100 Amp now). Currently, we have a service drop and we will move it to underground. The transformer is 150' away from the main panel on the garage wall. Once all the trench work is done, we will do a lot of landspace work, so it would be very disruptive to re-trench in the future again (if needed).

Given the above information:
(1) Should we go with 200 Amp or 400 Amp service?
(2) Even if we go with 200 Amp service, can we put a larger conduit (or extra conduits), so it would be easier to upgrade to 400 Amp in the future?
(3) What would be the approximate cost for 200 Amp or 400 Amp service upgrade? (excluding trenching work, including PGE cost + main panel replacement by an electrician)


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I would go with 400A NO QUESTION at this point given your plans, even without the tankless (which I would not consider if electric).

I would not even guess at a price considering your location and the fact that we know nothing about the site details.

    Bookmark   June 3, 2013 at 8:00PM
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Thanks, petey_racer. Regarding the site: It is a flat lot, there is nothing between the transformer and the main panel, there will be 150' of straight trench. The soil is mostly clay.

    Bookmark   June 3, 2013 at 8:10PM
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Sorry, I meant the job site details, meaning where is the panel; where will the meter go; how is the access for wiring; etc.

I know most panels in Cali are outside and many times flush with stucco, which GREATLY adds to the cost of service upgrades.

    Bookmark   June 4, 2013 at 6:55AM
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May I suggest some electricity-saving options? Use your heat pump system to heat water. Use install an induction cooktop.

    Bookmark   June 4, 2013 at 2:25PM
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Thanks ionized. I did not know that the heat pump can both heat water and house :) That can save 4.5kW. Induction cooktop is also an option, with around 9kW max power.

    Bookmark   June 5, 2013 at 2:51PM
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Ron Natalie

He's referrring to it in cooling mode, you can transfer some heat to the warm the water going into your hot water heater. Not all heat pumps have the feature however.

    Bookmark   June 6, 2013 at 8:31AM
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Actually a desuperheater can make hot water in heating mode also. My geothermal unit has a DSH and I get hot water in both modes. In the winter, it is capturing heat from the compressor.

    Bookmark   June 6, 2013 at 4:41PM
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You might have to go with a commercial-grade mini split system to get hot water from it.

    Bookmark   June 6, 2013 at 4:58PM
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I went with 200A when I remodeled. Neighbor went with 400A when he remodeled. He's happier.

    Bookmark   June 7, 2013 at 8:55PM
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Thanks, everyone. I think I will go with 400 Amp.

    Bookmark   June 10, 2013 at 1:53PM
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