I have an old GE TM1010 panel which only two spaces available from the same hot bus bar. My question is would I be better off installing two tandem breakers in order to free up a space for a 30A double pole CB or to install a subpanel.

Specific info:

House is just under 2000 square feet. The main service is 100A. It has gas stove/oven, gas hot water heater and lighting/receptacle breakers are an even mix of 15A and 20A CBs. The central A/C fed off a dedicated 40A breaker in the main SP. The main SP is located at the front of an attached garage and the laundry room where the dryer in question is located at the rear (approx 10-12 feet). My original plan was to replace 2 15A and 2 20A breakers with tandem breakers so as to obtain access to both hot bus bars to install the 30A double pole breaker as there will be no further additions to the home. However I wonder if adding a subpanel would be better.

Read the fine print on your panel. It will give a limit on how many poles you can use in it. Count your breakers. If you can add more poles, the tandem breakers is the way to go.

You should be able to move one existing breaker to one of the spare slots to give you two slots on both legs.

On a 2K sq ft house, 100 Amp max, I suspect that you should call an electrician or several and talk about bringing you up to the 250 Amp service.

Unless you are very skilled with electricity, you had better let a licensed electrician do the work. The biggest safety concern would be pulling the meter while the work is done.

If you do not do this properly we could all get to send your family flowers and condolences over their loss. :).

Just out of curiosity, how old is the house and wiring?

Thanks. The house and wiring are about 20 - 25 years old. The box says it will accommodate 20 poles and at present has 18. So I presume the least complicated way is to replace some of the circuits with tandem CBs.

Thanks. The house and wiring are about 20 - 25 years old. The box says it will accommodate 20 poles and at present has 18. So I presume the least complicated way is to replace some of the circuits with tandem CBs.

Stop right there! If you are considering doubling the load on a breaker by connecting two circuits to one breaker, you are asking for a fire. Not to mention that you will immediately be in violation of code.

If you are talking about pure tandem (one breaker above the next breaker) that's fine. Or better yet, 2 breakers one lever that turns both off at the same time. I need to get a book out to see what's actually available.

Also, consider the amperage draw of the new dryer as opposed to the old dryer because you may need to pull a larger cable. Like a 10/3 or an 8/3 depending on the amperage you now need.

Wiring that's 20 to 25 years old deserves a look see to make sure it is still safe

Moving a breaker is a good move to allow access to both poles(phases). Be sure that the breaker you move is not part a multicircuit, or neutral can be overloaded. Look for a lone circuit to relocate.

There is no such thing as a250 amp service. There is 100, 200, and 320 amp. Since most of your major appliances are gas, the 100 amp service you have will accept a 30 amp circuit just fine.

Cable installed 25 years ago should be BX or Romex, and I would not be concerned with any issues. What type of cable do you have?

I am not sure where donf thinks you mentioned doubling circuits on a breaker, I don't see that you stated anything like that.

I assume you need to install a new cable for the dryer as there is not one now.

tkrussell,

Thank you for correctly putting into words as I have not done such a good job of it. You are correct in that I would be putting in an all new dedicated 10-3 cable for a new electric dryer. Currently the wiring in the house is Romex/NM wiring. I am not sure what stratmando was referring to when he mentioned "Be sure that the breaker you move is not part a multicircuit, or neutral can be overloaded. Look for a lone circuit to relocate." It looks like if I were to relocate 2 15A or 2 20A CBs to a tandem CB elsewhere in the panel, I would gain access to both bus bars needed to install my double pole 30A CB.

Til TK gets here, You can have 2 circuits share 1 neutral, but they have to be on opposite phases. It has a cancelling affect on neutral. If 1 circuit draws 10 amps and other circuit draws 12 amps, then neutral will draw 2 amps. The difference of the 2(subtract smaller one from the larger draw).
If they are mistakenly on same phase, then neutral would be carrying 10 + 12 amps=
22 amps. If you have romex, it would usually be done with 14-3 or 12-3, black, red, white, and your bare ground.
Just check that the breaker you want to move has a lone neutral(follow the wire on that breaker where it exits panel to see what is with it, if it just has a neutral and ground with it, you are OK. Any red with it, may have to move different breaker, the other bottom breaker?

TK,

I did not read that he was going to attach two circuits to one breaker, I wanted to make sure he did not do that as a method of consolidating breakers to free up a breaker.

The 250 Amps service, was a typo. Brain moving faster than fingers.

However, if you see me putting erroneous info, please whack me over the head. At best, I'm experienced at electricity and electronics but lousy on the code. I will always defer to a lic. Electrician.

OK I will, I keep a large piece of 500 MCM copper handy as a billy club, as most electricians do. Easy to explain to law enforcement that this is not a weapon, just some wire left over from a job.

Try to be as accurate as possible, I or others may not always catch every mistake, error, or bad advice. Thousands of people look at this website, and one error can be taken and put into action and result in a big problem for someone.

As far as advising everyone to hire a pro, good advice, but seldom heard. People will continue to do their own work, and are allowed by law in many states, as long as they only work in their own single family home, and apply for permits and inspections, if required.

I personally think that anyone that visits Home Depot, Lowe's, etc and buys electrical materials, or for any other licensed trade for that matter, show a license or certificate before purchase , but that's not going to happen, so I need to deal with it and give the best advice I can to prevent loss of life and property.

I hope everyone reads my Read This First sticky note before proceeding, wish I could make it mandatory. I really hate seeing fire apparatus and ambulances at people's homes.

At least those that ask questions here I have to assume are aware of the danger and are asking questions. I worry about all those that think they know and don't ask.

Jzarcone, follow Stratmando's advice about being careful of arranging breakers and circuits in the panel, add the 2 pole 30 amp CB and your good to go. Be sure to use a 4 wire 30 amp dryer outlet and cord.