Adding a new sub panel

I live in a 6 year old house that was built with 200 amp service. I have a Murray main panel. I did some work in the basement, added a jacuzzi and 5 rooms and have used all existing slots in the panel. Even those 15/20amp slots that were on a single breakers I have replaced with tandem breakers. I heard installing all tandem breakers for the 15/20 amp circuits was not a good idea because of heat disipation (sp?). My panel is in the basement which stays relatively cool. Now I need to add one more circuit (bedroom ceiling lights) and I'm out of room.

I want to add a sub panel but I have some questions.

How do I hook the subpanel to the main panel? I know, from readin other posts, I need a thick number 2 grey wire but does it get connected to the bottom of the bus in the original main Murray panel? I never seen a configuration with a sub panel hooked up. The sub panel will be located right next to the main at the same height.

Does NEC say I need a Murray brand subpanel?

Would you recommend that I take all of the circuits on the tandem breakers (about 5 of them) I installed for the basement project and move them to the subpanel with the new ceiling lights circuit and replace them with the old single breakers in the main panel from the original construction? I am not having a problem with these circuits.

If I get all the materials, how many hours do you think this project should take a qualified electrician to do? I have all the outlets/switches in the house defined which main panel slot they relate to on the inside cover of the main panel. He/she would have to attach sub panel to poured foundation basement wall, connect main panel to sub panel, possibly on your recomendaiton above, move 5 tandem breakers to subpanel and replace original breakers in main and hook up the new bedroom ceiling light circuit in sub panel. There is not any need to run any wiring or hook up ceiling lights/switches as this has all been done. I don't know if this requires any outside work at the underground utility post.

Thanks in advance for reading all this.

 

How many positions does your existing panel have, and how many of those positions are able to accept tandem breakers?

Answering these questions will tell you if you can or cannot install another tandem breaker.

I would first look to use another tandem breaker. If five tandems are allowed, then six most likely are also allowed.

As for the sub panel idea. No it does not have to be the same brand as your main panel. However, doing so might allow you to interchange breakers. You need four wires from your main panel to the sub panel. The size of these wires depends on the size breaker feeding the sub panel.

The breakers moved to the sub panel might depend on the wire routing. (The wires need to reach the subpanel.) It might depend on what breakers you remove install the breaker to feed the sub panel.

 

'Answering these questions will tell you if you can or cannot install another tandem breaker.

I would first look to use another tandem breaker. If five tandems are allowed, then six most likely are also allowed. '
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I'm not aware of any limitation in my main panel for the number of tandems allowed. I guess I wasn't asking if I should add another tandem breaker to the main panel. I don't have room in the main panel for another breaker.

So to add a sub panel, I add a large multi post breaker in the original main and feed the wire conected to that to the top breaker in the subpanel? Something like the hot water heater or stove breaker?

 

Bob was trying to save you money by avoiding the subpanel. There's nothing wrong with tandem breakers, despite what you've heard. If you would like to explore this idea, tell us the make and model of your current panel.

• A subpanel is connected to the main panel by installing a new double-pole breaker in the main panel. It is wise to plan the subpanel while you still have two spaces left in the main. If you don't have two spaces, then you'll either need to make room by using more tandem breakers, or you'll need to move two circuits from the main to the sub. This isn't usually too big of a deal if the sub will be right next to the main.
• The size of the wire depends on the size of the breaker you put in the main to protect it and the rating of the subpanel. 6/3 on a 60-amp double-pole breaker is very common for a subpanel. You can use #2 and a 100-amp breaker if you need to, but it's usually not required.
• You do not need a Murry subpanel just because you have a Murray main panel.
• I recommend you leave the existing tandem breakers alone.

 

My main breaker panel is Murray LC220PC.
Model 16 Type 1 enclosure
Murray Type G panel board
20 total slots, 10 to a side

Is there a limt to the number of tandem breakers I can have in this panel?

Also, the sticker on it says this;
Sum of breaker ratings conected to any one stab must not exceed 200amps.

What does that mean?

I wil probably go with adding a subpanel but does anybody know what type of Subpanel I can get that uses the same breakers as this main panel? I have a bunch of single pole breakers left over from adding my tandem breakers and I'd like to use them.
I'm thinking of a panel that I can add at least 6 single pole breakers into. I searched the internet for Murray subpanel and didn't come up with anything apparent.