Thoughts on tandem breakers?

[Phil Thien]

(1) Panel has five spaces left.

(2) My power needs in the shop are very simple. Two 110v circuits are all I need at this time. One would run a shop vac, which would be running when I operate my contractor's table saw, my small jointer/planer, my small bandsaw, etc (all of which have 2.5" ports).

(3) I'd sorta like to save four panel spaces (two on each side) after using the tandem. I'd use these four for two future 220-volt circuits (possible tool upgrades).

(4) Read "On the Internet" that tandems heat and false trip more often.

Should I use the tandem (I have already purchased but can return), or should I get two 15-amp breakers and switch to the tandem when I go with the larger tools?

The heating/false tripping thing is a concern. If it is true, I'd use two breakers. If it is Internet nonsense, I'd prefer to use the tandem.

[Jim O'Dell]

We have several of them in the panel for the house. 3 of them mounted next to each other. I've not seen a problem with them tripping in the 6+ years we've lived here. I doubt that they would sell them if they were a big problem. Even though they may not be as preferred as the regular single breakers, I'd say use them. Jim.

[David Helm]

+1 with what Jim said. I've had tandems in my main panel for years and have never had a trip.

[Phil Thien]

I don't think I can use one anyway.

My panel is a Siemens G2424MB1100CU.

According to this document:
http://www.kirbyrisk.com/woeb/datash...70_176_194.pdf

I have 24 spaces and I can have 24 circuits.

So even if a twin breaker would fit, I'd still not be able to exceed 24 circuits.

I have three 220-volt breakers now, but I imagine they each count as two circuits, right?

Edit: Yeah, the document says "full size breakers only," too. Oh well.

We have an electric clothes dryer and an electric range. Their days are now numbered.

I know, I know, I can run a sub panel. But the main is only 100-amps, and it is pretty new, too (9 years old). I should have asked for more than a 100-amp service. I had kinda assumed at the time he was going to put a 200-amp service in. I'm not complaining, I think he installed what he thought was a suitable service and he did beautiful work and gave me an outstanding deal.

Amazing how a small house can eat 24 spaces in no time, though.

That kitchen remodel was really a panel killer.

[Justin Freund]

100A is still a lot. Figure out how much power you actually use. Chances are its not close to 100A unless you're making hot water, have the AC on, drying a load of laundry, using all burners and the oven, and are vacuuming at the same time. If you're out in the workshop, you probably aren't using a lot of power at the same time inside the house. If you get rid of the electric appliances, you're even better off. I bet you can put in a sub without any issues.

[Rollie Meyers]

I don't think I can use one anyway.

My panel is a Siemens G2424MB1100CU.

According to this document:
http://www.kirbyrisk.com/woeb/datash...70_176_194.pdf

I have 24 spaces and I can have 24 circuits.

So even if a twin breaker would fit, I'd still not be able to exceed 24 circuits.



Edit: Yeah, the document says "full size breakers only," too. Oh well.

Your options are change the panel or add a subpanel or lose some appliances but a 12 or 16 space loadcenter would be cheaper then new appliances.

[Jim O'Dell]

I'm thinking out loud here, so this might not even be possible. Can you tag on at the meter and run to another panel? Or rather is there a special meter set up that allows for 2 panels, It wouldn't be a sub panel this way, but would just be another main panel with the need for it's own grounding rod. Call your electric company and see what the possibilities are. Explain that you need to run more power and would prefer not to have to change out the main panel. Jim.

[Phil Thien]

I'm thinking out loud here, so this might not even be possible. Can you tag on at the meter and run to another panel? Or rather is there a special meter set up that allows for 2 panels, It wouldn't be a sub panel this way, but would just be another main panel with the need for it's own grounding rod. Call your electric company and see what the possibilities are. Explain that you need to run more power and would prefer not to have to change out the main panel. Jim.

I doubt it, as the wires to the meter are sized based upon the load center. So if I ran two panels from the meter, I could overload the wires.

[Phil Thien]

Your options are change the panel or add a subpanel or lose some appliances but a 12 or 16 space loadcenter would be cheaper then new appliances.

My current 220-volt circuits include: 40-amps for the range, 30-amps for the dryer, and 20-amps for the A/C. I have no idea what those appliances actually draw. But I'm a worst case scenario kinda guy.

So would a subpanel be a wise thing to do? That is, if we're having a heat wave so the A/C is running a lot, and my wife decides to cook dinner and do laundry at the same time, I wonder how much of that 100-amps I'm using already? I'm not even including the TV the kids are watching, the computers they are using, the lights they have on, etc.

Then if I decide to rev-up the DC and start the table saw and start cutting 2" thick stock, I may possibly hit that 100-amps, no?

[Jim O'Dell]

Phil, if you are talking about the wires from the pole to the meter, I'd check with the power company. Somehow I doubt that they would set that wire by what load center the house was going to have. I bet it is sized for 200 amps at least. Now if you are talking about the wires from the meter to the panel, yes that would probably be true. But IF you can tag on at the meter before the wires go to the existing panel, then that wire gauge would not matter. Jim.

edit: Maybe this will be a little clearer: If there is a meter box that has dual lugs for 2 panels. Make more sense?

[Bruce Wrenn]

Phil, why not shift some of your current loads (general lighting, small appliance circuit, etc to tandem breakers and free up a couple of spaces. Be sure and NOT put both small appliance circuits on the same breaker though. You could then use "multi-wire branch circuits" to supply both two 110, and a 220 circuit using a two pole breaker. You will have to run a neutral, along with two hots. Remember that the feed to the stove is sized for ALL the elements to be on at one time. How often does this happen? All the machine tool circuits in my shop are multuiwire branch circuits, except for the air compressor, and welder. If you have gas, or oil heat, along with a gas water heater, then your 100 amp panel is more than adequate, IMHO

[John McClanahan]

I would use the tandem breakers now. If you do have issues, (I doubt you will) you will have time to decide what to do before you need the extra spaces in the breaker box.

If possible, try not to gang heavy use circuits, like kitchen and bathroom on the same tandem breaker. That will reduce the chance of breaker heating.

Personally, I have never experienced problems with tandem breakers.

John

[Phil Thien]

If you have gas, or oil heat, along with a gas water heater, then your 100 amp panel is more than adequate, IMHO

That is good to know.

I should be able to read the load on my 100-amp service by checking the meter. I won't be running the A/C any more this year probably, but next summer when my wife is cooking/doing laundry on a Saturday w/ the A/C on, I can check the meter and figure out how much power I'm using, right?

And then I can determine whether I want more than 100-amps before upgrading tools.

There is no hurry. It isn't like this sort of upgrade is around the corner. Just trying to keep my options open.

[Phil Thien]

I would use the tandem breakers now. If you do have issues, (I doubt you will) you will have time to decide what to do before you need the extra spaces in the breaker box.

Did you see my post where Siemens says this panel is good for 24 breakers and 24 circuits? I think I'm stuck at 24 circuits.

BTW, not that it matters any more, but Siemens makes TWO twin 15/15 breakers.

They make a Q1515U:
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

And also a Q1515NC:
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

The one that ends in NC says it is for "replacement purposes only."

Again, not that it matters any more, but does anyone know what the differences are between these, where the -U would be used and where the -NC would be used?

I gotta admit that this stuff is kind of captivating. I've been reading books and the NEC and stuff and I find it all very interesting.

[Rollie Meyers]

The OP's panel cannot accept twin breakers the panel is made for full size breakers only , & the use of twin breakers that will fit, non-CTL breakers made for panels built prior to 1968, is hack work.

A subpanel fed off the main panel would work,double taps off the meter can will not...