Electrical: sub-panel vs. 150Amp entrance

[nereo]

Here's my situation:  we're renovating a c. 1900 home and adding a pair of heatpumps, but our 100 amp circuit breaker is full.  No data on when that panel was installed but my best guess is sometime in the 1980s or early 90s based on wiring and style of breakers.

I've got two choices: install a subpanel with ~6 slots for a few hundred bucks or upgrade the entire entrance to 150amp service.  One electrician I spoke to gave me a non-bindning estimate of $1,000-1,500 (he would need to look more closely at the wiring and permits to give me a binding quote).

So - which would you do?  In terms of major draws we'll have the fridge, washer/dryer, stove, microwave and heat pumps (water heater is propane, though that might change).  I know most new homes start with 150amp service, but I don't know if I **need** it (or it will help 'future-proof') our home.

[JLee]

How much power do the heat pumps use? If you do have a need for additional power draw in the future, 100 amps may be limiting (electric cars, etc).  I would be more inclined to install a new/modern panel with 200 amp service (or 150 if that's all you can get) instead of daisy-chaining sub panels off of the existing smaller panel.

[Papa bear]

I’d pay to upgrade the service.  Why not look at 200amp?  You’re going to be pulling a lot of amps with a range, heat pumps, h20 tank (potentially), and drier.  Basically an all electric house.  My place was all electric from the 70’s and has 200 amp service from then.

Price of the install sounds about right for the work. 


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[Just Joe]

200 AMP service upgrade. Your home's next owner may have an electric car. A L2 charger requires I think 30 or 50 amps. Might benefit you when you sell.

[Ecky]

We recently installed a mini split in our home and needed some space in our panel. We opted for some thin breakers to free up some room as a temporary measure, and ended up just leaving it that way.

Our 100A service hasn't been an issue. Since we upgraded our dryer to a heat pump (which was free after rebates and incentives), that cut energy usage from 11 amps down to 0.3 amps when drying clothes. Our new mini split (heats half of the house) is rated for 3.3 amps typical / 10 amps peak. Even under worst-case usage in the house we're still a faction of capacity.

[Papa bear]

Ok add this up and then figure out for yourself what you think you’ll need. Obviously, not everything will run at the same time, but I can definitely see your fridge, heat pumps, h20 tank, and dryer going at the same time.  Or add a car charger and that could all run at night.  Or think the weekend in the summer. Maybe you’re baking a loaf of bread, Heat pump is running full bore to keep up, you’ve got your car plugged in, you run the dishwasher and a load of laundry in the wash and dryer.

220 volt stuff

Range 50 amps
Dryer 30 amps
H20 tank 30 amps
Minisplit 15-20 amps
Minisplit 15-20 amps

110 volt

Microwave 15-20
Garbage disposal 15-20
Fridge 15-20
Dishwasher 15-20
Washing machine 15-20
Bathrooms 15-20 x number of bathrooms
Lights, bedrooms, living, dining 15-20 x 3-4 circuits

Extras

Electric car 20-50 at 110-220 volt depending on install
Garage tools? Do you have a wood shop? Maybe you just run a shop vac and a table saw a lot 

If I’m upgrading service, I’m definitely going with 200 amp.  If I’m staying at 100, I’m going to hope to hell I can get away with the mini breakers (square D homeline boxes can accept them) and I’m going to keep an eye on my big appliances.  Maybe stay gas for h20, maybe switch out the range to gas, get a heat pump dryer or something like that.


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[big_owl]

I hate subpanels and any contractor at work that tries to pull that shit on me doesn't get another job from us.  I say upgrade the service.