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pcampbell 02-26-2008 01:56 PM

Do I need a new box?
We have an old "Murray" box with 12 regular size slots. I read something in another post asking about having only 1 bar for both neutral and ground. We also have that. Is that a concern? We are going to be doing a new kitchen shortly and I anticipate 4 new homeruns at least.

I am wondering if there is any reason we need a new box.

Is there any limit to, or disadvantage to running "half" size breakers? If there is not, by splitting up 4 full size into 8 half size we'll get the four new circuits.

On a side note, is it against code to have multiple supplies running into a single breaker? I noticed the previous owners have done this on a few of the breakers.

Please excuse my ignorant terminology.

CowboyAndy 02-26-2008 02:02 PM

You can only use the slim or double breakers if the panel is rated for it. What is the exact model of the panel?

It is against code to run 2 wired to 1 breaker unless the breaker is rated for it.

Are you remodeling the kitchen yourself?

pcampbell 02-26-2008 02:15 PM

Thanks for the reply. It is a Murray LC112DS. Apparently this was replaced by Siemens LC1224B1100 according to

I am hoping the panel is rated for it (???) because we had a licensed electrician come in to add an outlet and he added a slim breaker.

How might I figure out if the breaker is OK to run 2 wires into it?

We are still figuring out who all will be doing different aspects of the kitchen job. I would consider doing the electrical work myself if I am sure it's done correctly. It would also have to pass inspection.

Stubbie 02-26-2008 02:27 PM

There is no problem using tandems or in the case of a GE panel half size breakers. As long as the panel accepts them you can install them. The breakers that install in the panel should be listed on the spec sheet inside the cover door. One thing to watch is panels have a maximum number of circuits allowed, so do not try to install a non ctl circuit breaker if the panel says it doesn't accept 1/2" or tandem single pole breakers. Some breakers will allow two branch circuit hot wires to attach to the breaker. One manufacturer that allows this is square d, most that do will have a compression plate that looks like wire goes on each side of the screw.

Stubbie 02-26-2008 02:36 PM

Also a kitchen has several requirements by the NEC as to branch circuits and receptacle placement are you familiar with these? If not we can help you with that cause you will never pass inspection otherwise.

The single neutral bar in your panel is fine. What size utility service serves your home ?

pcampbell 02-26-2008 03:12 PM

Thanks again!

I am only familiar with that I need separate circuits for each dishwasher disposal, fridge and microwave, then at least 2 more circuits for the counter outlets which have to be every 4 feet (?). I think we would have a total of 4 counter outlets (small kitchen).

We have 100 amps to the house. We are pretty low on the energy usage in general. All CFL bulbs. The new appliances will all be Energy Star. We use about 300kw/h a month, but I'd guess half of that are computers (60 watts *4 machines * 24 hours a day * 30 days) for my job. I.e. low constant wattage. I'm guessing it would take using a lot of killer appliances to pull 100 amps. Maybe washer/dryer, blow dryer, coffee maker, toaster, A/C, fridge, dishwasher and microwave all at once. It would be a feat alone to get those all going simultaneously. Maybe a few teenage kids would help (we're far off from that!!). We do have gas clothes dryer, water heater, range, home heat.

Stubbie 02-26-2008 03:38 PM

1 Attachment(s)
Kitchen. GFCI protection is required for all receptacles that serve countertop surfaces in a dwelling unit. Itís not required for receptacles that serve built-in appliances that do not serve the countertop such as dishwashers and kitchen waste disposals.

Two or more 20 amp small appliance branch circuits shall be required to supply receptacle outlets in the kitchen, pantry, breakfast room, dining room area. However, a receptacle for refrigeration equipment can be on the small appliance branch circuit.
The small appliance circuit cannot supply appliances such as disposals, dishwashers, hood fans, or lighting outlets.
Not Supply Other Outlets. The two 20 ampere small appliance circuits required in Section 210-11(c)(1) for these areas cannot supply any other outlet(s). This means that the kitchen light cannot be connected to the small appliance receptacle circuit.
Exception No. 1: Clock Outlet. A receptacle solely for an electric clock can be connected to the small appliance circuit
Exception No. 2: Gas Fired Appliances. Receptacles for supplemental equipment and lighting on gas-fired ranges, ovens, or counter-mounted cooking units can be connected to the small appliance circuit

Kitchen Countertop Receptacles, Two Circuits Required. 125 volt, 15, or 20 ampere receptacles used for countertop surface appliances in a dwelling unit kitchen must be supplied by at least two 20 ampere circuits [210-11(c)(1) and 220-16(a)]. These small appliance branch circuits can supply receptacles in the kitchen as well as the pantry, breakfast room, dining room, or other similar areas where food is likely to be served.
Kitchen and Dining Countertop Receptacle Location. In kitchens and dining rooms of dwelling units, receptacle outlets for counter spaces shall be installed according to (1) through (5) below. GFCI protection is required for all 125 volt, 15, and 20 ampere receptacles that supply kitchen countertop surfaces [210-8(a)(6)].
(1) Wall Counter Space. A receptacle outlet must be installed for every kitchen and dining area counter wall space 12 inches or wider. Receptacles must be installed so that no point along the counter wall space is more than 2 feet (measured horizontally) from a receptacle outlet.
(2) Island Countertop Space. This Section mandates only one receptacle outlet to be installed at each island countertop that has a long dimension of 24 inches or greater, and a short dimension of 12 inches or greater.
(3) Peninsular Countertop Space. This Section mandates only one receptacle outlet to be installed at each peninsular countertop that has a long dimension of 24 inches or greater, and a short dimension of 12 inches or greater.
(4) Separate Spaces. When breaks occur in countertop spaces (ranges, refrigerators, sinks, etc.), each countertop surface is considered a separate counter for determining receptacle placement.
(5) Receptacle Outlet Location. Receptacle outlets shall be located above the countertop, but not more than 18 inches from the countertop surface. Receptacles shall not be installed in a face-up position in the work surfaces or countertops and they must not be located on the sides of cabinets

pcampbell 02-27-2008 02:40 PM

Thanks - Am I reading this correctly that the fridge and gas range may use the same circuit as one of the two required for counter top outlets?

In which case I need 4 new homeruns:

existing circuit can power some outlets, and fridge and gas range
1 new for more outlets to meet 2 circuit requirement
1 new dedicated for disposal
1 new dedicated for microwave
1 new dedicated for dishwasher

Are you all able to determine if my box is indeed rated for tandems by the model #? Again I would hope that if my licensed electrician did it, then its OK!

Stubbie 02-27-2008 03:09 PM

1 Attachment(s)
Yep, that is close enough. Don't forget the 20 amp branch circuit requirement for the minimum 2 small appliance circuits.

As for your question about 1/2 size can you clarify or post a picture of your panelboard. Murray to my knowledge has 'tandem breakers as shown below' designated MH-T but I am not aware of any 1/2'' breakers for a murray panel. Murray tandems are full size but two single pole breakers in one case. Does the old panel list the breakers it will accept? If the electrician installed a non ctl breaker meaning one that does not have the rejection feature so it can't be installed in a panel not rated for them he was incorrect in doing that.

LawnGuyLandSparky 02-27-2008 03:12 PM

Inside the panel door should be a label indicating the number of circuits your panel is designed for. It may be 12, it may be 16, 20, or 24.

If your panel is already fully loaded at this point, and considering that you have a gas range, water heater, heat, and clothes dryer, and you already have some circuits doubled up onto breakers, I would suggest that you upgrade to a 40-circuit panelboard.

This is known as a "lower 1/2 upgrade." I've done this a few times where the load of a home is not really large, but the need for additional circuits is beyond the size of some older, 100a panels.

Due to the negligable cost difference, I'd install a 200amp rated panel with 40 spaces. Ignore the 200a main breaker and instead install a 100 amp main in 2 of the 40 circuit spaces, and backfeed it. This will allow you to have a total of 38 circuits on a 100amp service without going through the expense of upgrading the entire outdoor portion, yet allows for that to be done in the future as well, if needs be.

HouseHelper 02-27-2008 03:15 PM

The Siemans panel you listed is approved for tandem breakers in all slots, so if it is a direct replacement for the Murray, then you may use them.

Many electricians (myself included) combine the disposal and dishwasher on a single 20A circuit so you may only need three circuits. ;)

Stubbie 02-27-2008 03:26 PM

I would agree with lawnguy that it sounds like your service is adequate but your panel just does not provide enough spaces for what you need. That being said if the panel accepts tandems you may use them. However doubling branch circuits on one breaker should be avoided IMO.

You have a murray panel that doesn't necessarily mean that it will accept tandems like its siemens replacement.

pcampbell 02-27-2008 04:12 PM

2 Attachment(s)
Here's the panel and the inside door. I guess I am confused as to what you say when you say "accept" makes me think that if it isn't allow to have them, they won't physically fit but not sure if that is the case. I had a licensed electrician put in the #4 and would very much hope he would have told me if this were not allowed.

220/221 02-27-2008 05:30 PM

"Accept" means that the bus (where they plug in) is configured in a "V" pattern to accept the breaker.

A standard twin wont fit on a bus that isn't "slotted" to accept them (unless you tamper with the breaker)

I'm not a fan of twin breakers and only occaisionally use them.

If you are adding several more circuits just change the panel to accomodate them with full sized breakers and maybe leave a couple of extra spaces.:thumbsup:

Stubbie 02-27-2008 06:51 PM

1 Attachment(s)
The wiring diagram shows no tandem orientations. Based on that diagram this panel will not accept them. It would be my guess that the electrician either used non ctl in the top left (thats not a murray) or he modified the murray tandems installed in the right hand column by breaking out the rejection tab so they would fit the panel. I also notice the space dividers removed where the tandems are installed except the upper left. Normally to install a tandem you would not have needed to do this.

IMO you either need a sub or hang another panel.

This is a diagram of a Murray LC12/24B1100 which shows as the model # indicates 24 circuits if all spaces are tandems. If it said LC12B1100 generally this means the panel has 12 spaces and only full size single poles can be used for a total of 12 circuits not considering double pole breakers.

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