How do you do a load calculation?

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Posted by: from Oceanside
3/24/2021 at 12:24:19 AM

I have a 100 amp panel and am thinking of upgrading to a 200 amp panel. However, they are saying, I will need trenching and 3 inch conduit.

Would it just be better to upgrade to a 125 amp?

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Date/Time3/24/2021 at 6:58:09 AM

To upgrade to a 200A service you would only need a 2 conduit if you are using copper conductors. If you were using aluminum conductors you would only need a 2 1/2 conduit. What load are you adding that requires you to upgrade your panel?


M&J Electric Inc.

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Date/Time3/24/2021 at 8:09:08 AM

Hello Bethel.

thanks for posting on Trustedpros.

A load calculation is needed whenever there is electrical load being added to your electrical system. For example, adding a hot tub, EV charger, second kitchen or building an addition onto the house.

A licensed electrical contractor will know how to perform a load calculation, and they will know what items can be de-rated within this calculation.

There are times when a 125A upgrade is sufficient; most electrical load centers are already rated for 125A in which case all that may be needed is a new main breaker and perhaps an increase in line conductors.

Additionally, a load calculation can be based on actual usage as supplied by your local utility provider. Again, a licensed electrical contractor will know how to calculate peak usage from the data provided by the local utility.

There is a bit of math involved in both types of load calculations which is why contacting a licensed electrical contractor is the ideal way to go.

All the best.


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Date/Time3/27/2021 at 5:55:59 PM

From hydro to your meter in many situations the wire is already 3/0 which is rated for 200A. The wire from the meter base to your house is smaller but can in most situations be changed easily. For 200a panel you need a 2 conduit not a 3 . According to the Ontario electrical code 3- 3/O RW90 conductors are allowed in a 2 conduit. If hydro has room in the transformer to allow a 200a panel I would recommend a 200a vs a 125a. The cost is not much different, if 200a is not possible I then go with the 125a. I hope this was helpful, feel free to reach out if you have any more questions.

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Date/Time3/28/2021 at 12:55:00 PM

If you consider reducing your electrical load by switching to a gas stove and a gas hot water heater, you will likely not have to change your electrical service at all.



Partex Design Build Ltd.

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