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Thread: Need more than 200 AMP residential service

  1. #1

    Default Need more than 200 AMP residential service

    We are building a new house in west-central Edmonton, and my builder has advised me the load calculation is already at 192.5 amps, and that's without a couple electric deck heaters (2x25A) and an electric vehicle charger (40-60A). See the list below. The trench from the back lane is still exposed (service going to detached garage at backlane, then underground to the house).

    I was advised the only solution is to go with 400amp service from Epcor, which requires a separate electrical/transformer "room", special permits and wiring, and the associated additional costs will be tens of thousands of dollars ($40,000).

    Is there NO other way to supply more than 200 amps to a single dwelling home, and still pass an inspection? I know you can "add on" electrical items later, after the house is built. However, I do not want to add electrical stuff (ex. deck heaters) without pulling a permit. If I have a fire, I don't want my insurance company saying insurance is void because something was done without a permit.

    LOAD CALC:
    Based on the square footage there is a basic house demand of 11000 watts = 46 amps
    Steam shower load of 13000 watts = 54 amps
    Air conditioning load assumed = 40 amps
    Floor heat mat load assumed = 8 amps
    Induction range load of 12000 watts with demand factor applied = 25 amps
    Dryer 30 amps at %25 = 7.5 amps
    Oven 6700 watts = 28 amps at %25 = 7 amps
    Steam oven 20 amps at %25 = 5 amps

    Total = 192.5 amps
    Last edited by blake; 02-08-2019 at 12:07 AM.

  2. #2

    Default

    How likely is it that ALL of that load would be required at the same time?
    I am in no way entitled to your opinion...

  3. #3

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    Very unlikely. But I understand City of Edmonton inspectors will not pass the electrical inspection if this load calculation exceeds your service (which was initially planned to be 200 amps). The code is written for the worst case scenario, where everything is running simultaneously.

  4. #4
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    Welcome to rural life blake. You should see my electric bill and transformer rents.

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    i can't imagine a single family home that wouldn't be more than adequately serviced with a 200 amp panel. as far as i know, the load calculation for the service sizing isn't the total load of everything in the home being on at the same time (ie dryer, dishwasher, air conditioning, outdoor heaters, car charger, oven and stove and microwave and all your lights and tv's and computers etc.). i would have an electrical engineer check his calculations and suggest some options (ie maybe using three 100 amp sub-panels on a splitter instead if a single 200 amp panel). my guess is your builder or his electrician is just running out of space for breakers in a 200 amp panel rather than your exceeding the load requirements of a 200 amp service. i'm pretty sure it's common to see a 200 amp panel with a 100 amp service for that reason. if that's the case in your home, then it's usually in the $1,500 range to upgrade from a 100 amp service to a 200 amp service if the cubicle it's being drawn from has the extra capacity. i'm not an engineer but what you've described doesn't seem to make sense in terms of what's required or the proposed solution or the cost.
    Last edited by kcantor; 01-08-2019 at 10:22 PM.
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  6. #6

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    Quote Originally Posted by kcantor View Post
    i can't imagine a single family home that wouldn't be more than adequately serviced with a 200 amp panel. as far as i know, the load calculation for the service sizing isn't the total load of everything in the home being on at the same time (ie dryer, dishwasher, air conditioning, outdoor heaters, car charger, oven and stove and microwave and all your lights and tv's and computers etc.). i would have an electrical engineer check his calculations and suggest some options (ie maybe using three 100 amp sub-panels on a splitter instead if a single 200 amp panel). .
    I was told the City of Edmonton inspectors do this type of load calculation, assuming everything will run at once. As you can see some items such as dryer and oven have a demand factor, as they do not use 100% of the load when running, whereas most others, like a steam shower generator or heater, gets 100%. Its not a panel issue as panel isn't even in yet.

    Can anyone confirm the city actually does this calculation and enforces it?

  7. #7

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    Why is there no demand factors applied to:

    • Steam shower load of 13000 watts = 54 amps
    • Air conditioning load assumed = 40 amps
    • Floor heat mat load assumed = 8 amps
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    r
    Quote Originally Posted by blake View Post
    Quote Originally Posted by kcantor View Post
    i can't imagine a single family home that wouldn't be more than adequately serviced with a 200 amp panel. as far as i know, the load calculation for the service sizing isn't the total load of everything in the home being on at the same time (ie dryer, dishwasher, air conditioning, outdoor heaters, car charger, oven and stove and microwave and all your lights and tv's and computers etc.). i would have an electrical engineer check his calculations and suggest some options (ie maybe using three 100 amp sub-panels on a splitter instead if a single 200 amp panel). .
    I was told the City of Edmonton inspectors do this type of load calculation, assuming everything will run at once. As you can see some items such as dryer and oven have a demand factor, as they do not use 100% of the load when running, whereas most others, like a steam shower generator or heater, gets 100%. Its not a panel issue as panel isn't even in yet.

    Can anyone confirm the city actually does this calculation and enforces it?
    as i said in my first post, i would have an electrical engineer check his calculations and suggest some options.
    "If you did not want much, there was plenty." Harper Lee

  9. #9
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    Our house was built 3 years ago.
    We have a legal garage suite with all appliances.
    Floor heat mats throughout the main house and an induction range. (2500SF house, 650SF suite)

    We have 100 A service and have never had an issue.
    We had talked about adding a swim spa at some point in the future, which would be 50-60A. That might require us to go up to 150A service, but that's an easy change from the alley. We don't have AC.

    The patio heaters should really be gas. Much cheaper to operate.

    200A should be more than enough for what you need.

    They can run whatever size line they want from garage to house to future proof it. I believe ours is all good for a 200A service (we have 100A panel in the house and 100A panel in the garage, but the main service is 100A)

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    Quote Originally Posted by Edmonton PRT View Post
    Why is there no demand factors applied to:

    • Steam shower load of 13000 watts = 54 amps
    • Air conditioning load assumed = 40 amps
    • Floor heat mat load assumed = 8 amps
    Heating and cooling loads are calculated at 100% demand, no factoring is allowed.

    Allowing 11000W for base load means the house has over 7000 sq ft of living space, in addition to one of the largest steam showers I have ever heard of. If those two line items are correct, there is virtually no way to keep the service under 200A with everything else you want.

  11. #11
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    I'd just delete the steam shower, as a mechanical contractor. You'll use it way less than you think and it'll require significant maintenance. And the one listed above does seem pretty huge. Quickly punching in a 5'x5'x8' shower with 1/4" ceramic tile spits out 6kW: https://relax-a-mist.com/calculator/

  12. #12

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    Quote Originally Posted by KevinW View Post
    Quote Originally Posted by Edmonton PRT View Post
    Why is there no demand factors applied to:

    • Steam shower load of 13000 watts = 54 amps
    • Air conditioning load assumed = 40 amps
    • Floor heat mat load assumed = 8 amps
    Heating and cooling loads are calculated at 100% demand, no factoring is allowed.

    Allowing 11000W for base load means the house has over 7000 sq ft of living space, in addition to one of the largest steam showers I have ever heard of. If those two line items are correct, there is virtually no way to keep the service under 200A with everything else you want.

    Thanks for the informative response
    Advocating a better Edmonton through effective, efficient and economical transit.

  13. #13

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    Quote Originally Posted by Edmonton PRT View Post
    Quote Originally Posted by KevinW View Post
    Quote Originally Posted by Edmonton PRT View Post
    Why is there no demand factors applied to:

    • Steam shower load of 13000 watts = 54 amps
    • Air conditioning load assumed = 40 amps
    • Floor heat mat load assumed = 8 amps
    Heating and cooling loads are calculated at 100% demand, no factoring is allowed.

    Allowing 11000W for base load means the house has over 7000 sq ft of living space, in addition to one of the largest steam showers I have ever heard of. If those two line items are correct, there is virtually no way to keep the service under 200A with everything else you want.

    Thanks for the informative response

    Apparently Epcor can provide 300 amp residential service but the transformer on our pole has to be upgraded. Is it typical that Epcor charges the homeowner for this ($15,000)?

  14. #14

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    It sounds like a lot especially since if you tore down your house and built a duplex, you would need the same service.

    Dealing with Epcor is a pain. 25 years ago, I managed a southside machine shop and bought several large lathes, mills, welding machines, plasma sprayer and other machines for our increasing business. We needed to upgrade our service. Our panel could handle the load but originally we had 3 transformers mounted between two poles along the street. Other businesses had similar setups. Years earlier, when there was a downturn in the economy, Epcor took away two of the transformers. Now we needed them back.

    Epcor refused to reinstall them. They said we needed a $40,000 pad transformer, blast wall and bollards etc. Meanwhile the businesses all up and down the street had their triple pole mounted transformers but Epcor said they were 'grandfathered in' but we had to have a pad mount.

    Luckily, the owner's brother was a retired electrician and found a used transformer, we poured our own pad to specs and did the job for $25,000
    Advocating a better Edmonton through effective, efficient and economical transit.

  15. #15
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    Quote Originally Posted by blake View Post
    We are building a new house in west-central Edmonton, and my builder has advised me the load calculation is already at 192.5 amps, and that's without a couple electric deck heaters (2x25A) and an electric vehicle charger (40-60A). See the list below. The trench from the back lane is still exposed (service going to detached garage at backlane, then underground to the house).

    I was advised the only solution is to go with 400amp service from Epcor, which requires a separate electrical/transformer "room", special permits and wiring, and the associated additional costs will be tens of thousands of dollars ($40,000).

    Is there NO other way to supply more than 200 amps to a single dwelling home, and still pass an inspection? I know you can "add on" electrical items later, after the house is built. However, I do not want to add electrical stuff (ex. deck heaters) without pulling a permit. If I have a fire, I don't want my insurance company saying insurance is void because something was done without a permit.

    LOAD CALC:
    Based on the square footage there is a basic house demand of 11000 watts = 46 amps
    Steam shower load of 13000 watts = 54 amps
    Air conditioning load assumed = 40 amps
    Floor heat mat load assumed = 8 amps
    Induction range load of 12000 watts with demand factor applied = 25 amps
    Dryer 30 amps at %25 = 7.5 amps
    Oven 6700 watts = 28 amps at %25 = 7 amps
    Steam oven 20 amps at %25 = 5 amps

    Total = 192.5 amps
    I don't see space heating in that list so I am assuming you are getting natural gas service for a furnace. The obvious answer in that case is to run a few more gas lines rather than spending tens of thousands on electrical upgrades. Gas range, gas dryer, gas deck heaters. Then look at downsizing the steam shower (13 kW will turn it into a sauna really fast) and maybe the AC (though if this really is a 7000+ ft^2 house it might actually need a 10 kW AC).
    Not sure of your driving patterns, but unless you need to simultaneously charge two cars at full level 2 rate you can probably make some cuts there too. If you have all night, 16 A per car will be plenty. EVSEs with power sharing are available now, so you can charge 1 car at 32 A or 2 at 16 A each.

  16. #16

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    Can you get a NG steam shower? Even if you spend $2k more you are ahead and cheaper rates too.

    NG dryer and NG stove is another good idea
    Last edited by Edmonton PRT; 11-08-2019 at 05:02 PM.
    Advocating a better Edmonton through effective, efficient and economical transit.

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