I was looking at my load center breaker panel to see where to put a couple of breakers dedicated to space heaters. I have a spare slot where I intend to put a tandem 15A breaker. I'm going to move a 15A load from the other side of the panel (it's 50A) to this new breaker so I'll have only one heater on each hot leg - better for when I'm running my generator.Anyway, my question is: is there any performance / safety difference between a full sized breaker and a tandem? Both my air conditioners are on full-size 20A breakers but there are also a couple of 15A/20A tandems.

No Difference from a performance or safety perspective. You can also install a sub panel but that would be overkill.

Both my house and my RV use tandem breakers with no problems.

No difference. Might as well spend a few might as well spendca few minutes phsses to neuteal voltage ensuring your loads are, in reality, balanced.

I have a tandem and it has worked flawlessly. However when I bought it hte (retired) electrician at Lowes said they were prone to nuissance tripping.

If you're running "one heater on each leg", you should use two single breakers rather than a tandem. You can easily make sure each breaker is on a different leg. If you're using a tandem breaker with two potentially unbalanced 110v loads, you can cause problems.

Full size breakers vs. tandem (double) breakers?

39 Replies

CJW8
Explorer
Sep 28, 2016
Just install your tandem breaker but don't put your two heater circuits on it. Move other loads around so that it will be more balanced. It will never be perfectly balanced. Your microwave and coffee maker only run for a brief period of time.
mike-s
Explorer
Sep 28, 2016
ScottG wrote:
mike-s wrote:
ScottG wrote:
A tandem breaker will work just fine for the OP. There is no need to run a space heater off each leg. It just doesnt matter.
It may matter. As he said in his original post - "better for when I'm running my generator." He may have a split-phase gen set.

And that's what I said in another post. If there's a generator or inverter involved then loading matters.
Don't expect us to keep track of all your inconsistencies.
ScottG
Nomad
Sep 28, 2016
mike-s wrote:
ScottG wrote:
A tandem breaker will work just fine for the OP. There is no need to run a space heater off each leg. It just doesnt matter.
It may matter. As he said in his original post - "better for when I'm running my generator." He may have a split-phase gen set.

And that's what I said in another post. If there's a generator or inverter involved then loading matters.
Otherwise, again like I said before, as long as you don't exceed specs it just doesn't matter.
That situation aside, in a case where the micro, and a couple of other large loads are involved it still doesn't matter because there is plenty of current avail. - as long as you don't exceed specs.
mike-s
Explorer
Sep 28, 2016
ScottG wrote:
A tandem breaker will work just fine for the OP. There is no need to run a space heater off each leg. It just doesnt matter.
It may matter. As he said in his original post - "better for when I'm running my generator." He may have a split-phase gen set.
joebedford
Nomad II
Sep 28, 2016
You can see where I've removed the breaker on the left that there is only one bus bar - access to only one 50A leg.

EDIT: it's my plan to install a tandem 15/15 breaker on the left and move the wire off the 15/20 tandem just to the the right of the 50A 2-pole main breaker to one of the two new circuits.
PUCampin
Explorer
Sep 28, 2016
The only time I have seen an issue with tandem breakers is when used with a multi-wire branch circuit (when 2 hots share a neutral). Not likely to see this in an RV, but I had to correct 3 of these when I bought my house so I think of it anytime someone mentions tandems :)
westend
Explorer
Sep 28, 2016
mike-s wrote:
westend wrote:
Not at all. The OP wishes to run two heaters with a 50 amp service. He wishes to balance the loads between the two legs of his 50 amp service.

If the tandem breaker or two single breakers only attach to one leg of his 50 amp service, he is not balancing the load between the two legs.
I don't think he's planning on connecting the circuits for both heaters to the new tandem.

He wants to move the circuit supporting one of the heaters to the other leg. To do that, he can replace an existing full size breaker on that other leg with a tandem, and reconnect the exiting load to one side of the tandem. He can then connect the heater circuit he wants to move to the other side of the tandem. Done - he has the heaters on different legs.
Exactly how I understood it and Joe states (a couple of times). I get it entirely, I took some time to balance the few meager loads in my 50 amp load center, too.
joebedford
Nomad II
Sep 28, 2016
tenbear wrote:
Both my house and my RV use tandem breakers with no problems.
My stick house uses mostly full size breakers in the main 200A panel, but the generator panel uses all tandems - 8 positions for 16 circuits.
westend
Explorer
Sep 28, 2016
Joe,
Do exactly like you planned. You have been dutifully scolded and probably by users that don't have 50 amp service.
joebedford
Nomad II
Sep 28, 2016
ScottG wrote:
A tandem breaker will work just fine for the OP. There is no need to run a space heater off each leg. It just doesnt matter.
As David P wrote, we're making this more complicated than it needs to be.
Why doesn't it matter? I thought load balancing was important. I know each leg is 50A but if I try to run 2 heaters plus a coffee pot and the microwave ON THE SAME LEG it might not work.

Besides, even though the breaker says 50A, my generator's breakers say 25A and 30A.

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Full size breakers vs. tandem (double) breakers?

39 Replies

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