Splitting Service in Duplex

Old 07-16-08, 10:52 PM
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Splitting Service in Duplex

Hi All Need Some Info,

I am currently remodeling a duplex in Southern NJ. The duplex used to be one a single service, gas and electric. I currently do not have the upstairs apartment rented and I have the place gutted. I already seperated the heat and now it is time for the electric. I am a degreed electro mechanical engineer by trade so I have a pretty good working knowledge of electric circuits. However, I am lacking knowledge of electrical codes. I was going to purchase the current NEC book but can't find one for under $50. So I figured I'd get just as good info from you guys, so here it goes:

I already have the permit to do the work. In NJ you can do your own electric on a multi family home as long as you are the home owner, and you live in one of the units. To get the permit I drew up several schematics of all the circuits, wires, etc... The local inspector approved the drawings so I'm good there. However in the schematics I did not detail how the service entry is going to be set up. I need to know what is code and what is not regarding the service entry. First question being where can I put the main breaker? Can it be put in a closet? Can it be put on an exterior wall? Can it be put on an interior wall? What is the difference between a main breaker, a load center, and a main lug??? What are my options to get the service to the panel in the first place??? For instance, say the new meter is placed at exterior ground level. The service will come from the poll to my house, then "drop" down to the electric meter. What next? Can the service line immideatly come into my basment and then up the exterior wall on the inside of my house to the second floor main breaker? Or would I have to go from the meter directly back up the exterior of the house and then punch into the second floor apartment main breaker? For both of these options what do I have to do regarding the wire? What size, and does the wire have to be in any kind of conduit?

I want to do the most of the work myself. But I think I'm gonna hire an electrican to finish the work from the drop to the meter. I should really hire an electrican to run everything from the drop to the main breaker, but electrican's are so damm expensive that even if it takes me a week to get this right its still cheaper.

I have several other questions, but I just wanted to start off there. Any information is greatly appreciated.


Old 07-17-08, 12:44 AM
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For the duplex apartment set up the codes are the same as single family homes are unless your local codes do show up diffent.

Bathroom mantory GFCI and decated circuit { 20 amp }

Kitchen Receptales min of 2 circuits 20 amp full GFCI'ed and the Kitchen lighting circuit have to be sperated from countertop circuits

Dinning room can tie to kitchen circuit { if your place have that }

IIRC The New Jersey is on 05 code { they should be on 08 code pretty soon but check with your building inspector for latest code verison }

Bedroom have to be AFCI'ed

No breaker box in cloth closet.

No bare luminarie in cloth closet.

Now for the metering set up this will get little tricky IMO I rather have electrician to deal with that part due the NEC and local code may come up and with overhead drop down to the meter box then if you have one breaker box in basement that fine but for upstair you will need a disconnect switch right below the meter itself or have disconnect switch in basement right next to your exsting breaker box. { this part is very circital due the local code and NEC codes}

The size of breaker box will very dependet on the load demand caluations this is the only legal way to determed the size of breaker box and btw per NEC code the min main breaker size is 100 amp.

You think the Electrician is expensive ?? not really with good trained electrician can do the task and have good anknowage with codes and many time it will jusify the cost.

You can call the electricians for the estames and make sure they are bidding simuair situaton almost like apple to apple if ya get my drift. ask 3 Electrical contractors to see where ya at.

and yes of course new ground rods also.

Humm before I forget this.,

The common 6/12 rules on most rooms the 6/12 refered to the mesurement on the wall receptales you can start the mesurement from the door and work it way down like at first receptale at 6 feet from door then next one about 12 feet apart there on but normally I space them little more tighter than that I useally use 5/10 spaceing unless something will required tons of plugs then I will change arrangement.

But the Kitchen all bet is off they used 2/4 rules there.

If any room you plan to have ceiling fans make sure you get fan rated box and also use 12-3 or 14-3 NM the reason why I suggest that so one wire is used for fan while other wire is use for light which it is common for me do that because not all fans have remote control on it. { of course two gang wall switch box there also }

humm For the Landry room area it kind pretty tricky there I know some duplex apartment do have two set of washer and dryers but the way it set up one group of washer and dryer run from downstair apartement while other group of washer/dryer from upstair apt so that mean you have to bring down the washer and dryer circuit to the basement unless you have landury room upstair that will be little diffrent.

hope that will cover most of details here for now., I am sure there is other members will chime in with more info also.

Yes there is electrical code book in Libary centre you should have one there.

Old 07-17-08, 02:27 AM
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To add to what Marc has already said, the Code requires the unfused service cable inside the house to be "as short as practical". Most times this means that the meter is mounted back to back with the panel on an outside wall. Since you already have service to the building the Code requires the services to be grouped. This may require an exterior disconnect be set next to the existing service. Ask your inspector.

Have you considered just feeding the second unit off the existing service?

A main lug panel just has lugs to land the wires. It does not have a way to turn it off at that panel and is not what you want for your application unless there is a breaker or disconnect ahead of it. . A main breaker panel has a breaker that controls all the branch circuits in the panel. A load center in a house is typically a panel with a main breaker.

The panel will require a working clearance of 30 inches wide by at least 36 inches deep, floor to ceiling. Think of a refrigerator box. The panel does not need to be centered in the 30 inch width. The does needs to open at least 90 degrees. No breaker can be higher than 6' 7" to the center of the operating handle.

The panel cannot be in a bathroom either.

Last edited by pcboss; 07-17-08 at 07:12 AM. Reason: added breaker height note
Old 07-17-08, 08:47 AM
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$50 is not a bad price given your savings over having someone do it who knows the requirements. In other words, penny-wise, pound foolish.

Check your library for "Electrical Wiring Residential" by Ray Mullin. It probably costs more than $50 but it's a good, detailed primer.

There is also a link somewhere at the top of this forum to the online NEC, although that's pretty hard to navigate until you have the applicable citations .... maybe from the inspector's correction order.
Old 07-17-08, 09:32 AM
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Originally Posted by nicstefa View Post
I was going to purchase the current NEC book but can't find one for under $50.
The NEC itself is a bit of a dense read anyway. Check out Wiring Simplified for about $10, or Wiring a House by Rex C. Both of these take a more task oriented approach to the code than the verbose listing of rules you'll find in the NEC.

You can view an online preview copy of the NEC here: http://www.nfpa.org/aboutthecodes/Ab...&cookie_test=1

First question being where can I put the main breaker? Can it be put in a closet? Can it be put on an exterior wall? Can it be put on an interior wall?
In the main panel of course! :-) I think the other posters have adequately answered panel position.

What is the difference between a main breaker, a load center, and a main lug???
The load center is the large metal box which contains the breakers, a.k.a. breaker panel, fuse box, etc. A main breaker load center is one which contains a large breaker to limit the current for the entire service, usually 100A-200A. All of the branch circuit breakers are "downstream" from the main breaker. A main lugs only panel is a load center which does not contain a main breaker -- the feeder wires bolt directly onto the panel lugs. An MLO panel is used where main breaker protection is provided further upstream in a different panel within the building. For example, you could have a meter/main combo outside which is a box that has both a meter socket and a main breaker. This could then feed an MLO panel inside the house.

For both of these options what do I have to do regarding the wire? What size, and does the wire have to be in any kind of conduit?
Most jurisdictions allow either plastic or metal conduit, or service entrance (SE) cable. Personally, I always use conduit as I do not believe that exposed SE cable is protected well enough. If the service drop is adjacent to a driveway, metal conduit or schedule 80 PVC is probably required for protection from damage.

The size of the conductors will be determined by the amperage of the service(s). You calculate the required amperage by doing a "demand load calculation". Either of the books I mentioned cover the procedure as do a few websites if you search Google. The minimum service size is 100A.

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