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milkweed
load balancing on a residential service panel
milkweed

Reading a book from the library about wiring a residential house.
In the section on service panels it talks about load balancing to keep the heat that the panel emits to a minimum.

We have 240 volt electric baseboard heaters in our house. Based on how the legs of the service panel zigzag, does this mean that the two adjacent 20 amp breakers that protect one of these circuits are load balanced?

If so, then does the load balancing consideration only apply to the sum of 120 volt circuits?

Re: load balancing on a residential service panel

Milkweed, if you have a typical 120/240V panel you generally don't have to worry about load balancing.

All 240V loads are automatically balanced.

If you see all your single pole (120V) breakers side by side and don't have a lot of portable heaters or window air conditioners you should not be concerned.

milkweed
Re: load balancing on a residential service panel
milkweed
The Semi-Retired Electric wrote:

Milkweed, if you have a typical 120/240V panel you generally don't have to worry about load balancing.
All 240V loads are automatically balanced.
If you see all your single pole (120V) breakers side by side and don't have a lot of portable heaters or window air conditioners you should not be concerned.

Sorry for resurrecting this thread, but I have a follow on question.
Recently we decided we want to add a mini-split.
As I mentioned before we have 240 volt service, and the unit we are looking at requires 240v.
Our service panel has two empty slots remaining, one at the bottom of either side of the panel.
Does the fact that the empty slots are opposite each other automatically indicate they are would be load balanced?
or do I need to take the cover off of the panel and look to see what legs the breakers would plug into?

Jack
Re: load balancing on a residential service panel
Jack

You should rearrange because for a 240 v unit the breakers should be a double breaker with both halves tied together not 2 separate breakers.

Jack

George
Re: load balancing on a residential service panel
George

I feel impelled to comment because there is so much misinformation on the internet about residential load balancing -- including from people who claim to be professionals. The comments above are correct, but the original question came from someone who "read a book from the library about wiring a residential house. In the section on service panels it talks about load balancing to keep the heat that the panel emits to a minimum." What is with that? First of all, if the panel is wired correctly there should be very little heat -- because there should be no appreciable resistance in the panel wiring. If the wires are getting hot it is because they have too much load (which should not happen if they were sized correctly for the circuit breakers they are connected to). 

Residential wiring has 3 cables, two "hot" and one neutral. For 220 volt circuits, the power comes on one hot wire and returns on the other. This alternates 60 times a second. For 110 volt circuits, the power comes on one hot wire and returns on the neutral. Now, some people become concerned if more power comes from one of the hot wires than from the other. They think it should be "balanced."

For an analogy, assume you drive to an office with two parking lots. Each lot has 20 parking spaces. But only 15 people drive to the office. It doesn't matter if they all park in one lot. It is the same with the service panel. It really doesn't matter if all of the 110 circuits are on the same hot wire, or leg, of the panel. (In practice this would be extremely unlikely since panels are designed so that the circuit breakers in a column alternate between the two hot legs of the panel.)

Some people note that "balancing" the power drawn by 110 circuits across both legs reduces the current returned on the neutral leg, thereby reducing the load on the neutral line. This is true, because although all the power still returns through the neutral leg, whether balanced or not, when the power demand is shared between the two hot legs, the return is also shared at different times. So when one leg is returning power to neutral, the other leg is not. Again, this alternates 60 times a second. So yes, you can reduce a peak load on the neutral by sharing power demands between the two hot lugs. But again, even if by some weird way of wiring all the 110 power traveled from the same hot leg and returned through the neutral leg, the cable is almost surely sized large enough to accommodate it. So there is no reason to worry about "balancing" a residential service panel, regardless of what books in the library (or numerous internet sites) may claim.

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