I am re-wiring an old house. It is a small 2 bedroom, 1 bath house. We put in a 200 amp service and need to run a service entrance cable about 20 -25 ft to the inside breaker panel. My question is how big of a gauge wire should we run for the service entance cable. #? 3 conductor with ground in copper. We have 18 -110v outlets, 3 - 220V outlets (Window AC, Kitchen Stove and clothes dryer), 3 ceiling fans with lights, Electric bathroom heater in ceiling. Etc.
Thanks

I'm really not trying to be a snot when I say this, but if you have to ask in this case, you may not be qualified.

I think its one thing to work within a panel. To run service to the panel is another. Don't tighten that connection correctly and you're certain to have a fire eventually.

I'd personally hire a licensed and qualified electrician to run service to the panel.

I know the guys in the know will have some advice...

Acually KP I'm helping an electrician wire my house. I do the grunt work, he does the real wiring. The reason for the post was to just check and see if important things like the service are being done correctly.

I'm sure one of the pros here can confirm the demand need.

First off, a 200 amp service with a panel 20-25 feet away shall have a disconnect outside at the meter location. This can be either a 200 amp breaker, or fuses, in a NEMA 3R Raintite enclosure. Some meter trim come with a disconnect built in together.

Agai, due to the distance, the cable can be a #4/0 XHHW insulation Aluminum 4 wire cable. This is called SER cable. This is a very popular cable. Even thou some aluminum cable is listed to be connected without an anitoxident treatment, "grease" treatment similar to gray lotion, most electricans still use it.

Another important issue is grounding at the panel. The neutral must be isolated from the backbox of the panel and no green or bare grounds shall be connected to it, only branch circuit neutrals. A separate ground bar (terminal strip) shall be bolted to the panel backbox and this is for all the greens and the bare wires, including the bare in the SER cable. Connected in any other way can cause various problems to detailed to go through here.

If you chose copper, and keep in mind, aluminum feeder cable is fine providing it is installed per manufacturers instructions, cable similar to SER cable is not very common, but is available usually by special order.

You may be able to wrestle 2 inch PVC conduit in , and you can use #3/0 copper wire with THHN/THWN insulation, three for the feeders, and a #6 copper ground green wire.

By the way, again due to the distance and the main breaker located outside, the system ground must connect to the neutral out at the meter/disconnect.

This system is usually two eight foot ground rods , spaced 6 foot or more apart, and a wire going the water system. If you have a water meter, the #6 wire may need to connect to both sides of the water meter to jump out the meter, so to speak.

Hope this answers your question.

Friend has a permit,right?

Yes, we have a permit. I'm putting the house up for sale when all of the renovations are complete so the electrical has to be inspected by the city. One thing that has me concerned is the fact that the service cable that the electricians are having me locate and get is #1-3 w/ground copper. None of the supply houses stock this cable. A 200A service is what is required by the city. I would think it would be readily available. In my mind this raises a red flag. Also, the electricians are saying that you size the service cable to the panel inside the house which is under 200A and there will be a 100A breaker on the primary panel outside so that the house can only draw 100A. Thanks for all your input. This is a really great website

Well #1 copper has a ampacity of 150 amps , when used for residential service.

I do need to make a correction, you can use #2/0 copper for 200 amp residential service, I gave you #3/0, which is for all applications other than residential.

Whoever signs the permit, even if the inspector does not catch the mistake, will be held liable for any problems that occur later. So if the #1 does get installed, the permittee will own it.

You as the seller, may be doubly responsible, as the seller of a property with a faulty condition, that you were knowledgeable of and possibly installed or party to.

You may want to check with an attorney for the exact liability exposure.

Make this go away, and install either #2/0 copper or #4/0 aluminum.

The #4/0 Al SER cable is readily avaialbe at every electrical supply house, and every big box home improvement store. So simple to make this all go away.

I am trying to follow what is being installed. City wants a minimum[ of 200 amps, but the main panel is less than 200, then you do not have a 200 amp service. A little difficult to determine exactly what you are installing. I hope I have cleared up any question you still may have.

TK and others, thanks again for your input. Let me try and clarify the situation. The city code requires 200A service at the primary panel outside on new consruction and re-wires so that all residential home are upgraded. I suspect this is driven by the fact that the people that write the city codes are mostly electricians and enfluenced by local electrical contractors and electrical equipment suppliers.
I guess my real question here is, what parameters do you use to determine the size of wire used that feeds the secondary interior panel:

A) the rating of the primary outside panel regardless of any breakers or fuses that would limit it's potential. In this case 200A

B) the rating of the inside secondary panel regardless of any breakers or fuses that would limit it's potential. In this case I believe 150A

C) The potential of the inside panel after considering it's potential that would be limited by the number and size of breakers installed for the circuits installed in the house.

I hope this is a little clearer.

Thanks

Having a little trouble following this. What do you mean by primary panel outside? Does this mean you will have a 200 amp breaker panel outside? Will this contain branch circuit breakers, and then you will have a subpanel in the basement which will be 100 amp?

The inside panel will have an amp rating, I get from your post 100 amp rated. This panel must be protected by a circuit breaker, 100 amp in the outside panel, the wire can be # 3 copper THHN or XHHW insulation or # 2 aluminum XHHW insulation, three wires each plus a ground, lets just keep this at #8 copper to keep it simple.

The outside panel needs to have a 200 amp breaker protectng it.

Is my understanding correct? Does any of this make sense?

Just reading some of this and was curious since it has been said the distance from the meter base to load center was 20-25 feet it required a disconnect at the meter base. If the distance is less than that, is a disconnect still required at the meter or will the main in the 200 amp load center serve for this?

The location of a main breaker is up to the local authority and/or the local utility company. It is intended to be as close to the entrance of the service conductors in to the building as soon as possible. Practicality means that if a meter is outside, and the cable comes in just above the panel and drops down into the panel, there may be approximately 4-6 feet of exposed cable.

The code does not specifically state the maximum amount of cable that can be in the building with out a main outside. Many jurisdications rely on the 10 foot rule established by the code, and will state in their requirements after 10 feet, the main must be located outside, if 10 feet or under the main can be inside.

The reason for the main to be outside if the cable is 10 feet or over is the cable that feeds the panel is unprotected without a main being outside. Imagine a cable coming in from a meter, running 30-40-50 feet through a building, say a basement, and if damaged by a nali, screw, or someone using the cable as a clothes hanger, with no main breaker to trip in the event of a short, would continue to burn.

So, with the question posted stating the panel inside with 20-30 feet of cable exposed, this senario calls for a main breaker outside. A short distance is allowed exposed without a main.

If there is ever any question, default to installing a main outside at or in the meter trim, and you will be covered no matter what.

Fire depts appreciate having a main outside in the event they arrive to a structure fire, they can immediately shut all power off to a building if deemed necessary. If the main is inside, they will not endanger a firefighter to go into a burning structure just to find a main to shut off so they can hose the building with water or prevent the lives lines in the building from shorting and cauisng more damage.

I hope this helps explain the situation. If not get back with more questions.

In a few fires I witnessed, the fireman pulled the meter.

Pulling the meter is clever, and will shut down power to the building, however still dangerous. This will leave the two live line jaws of the meter socket exposed wide open to all personel in the vicinity.

They may do it in certain cases, where a structure is only partially involved, and they deterimine the structure can be saved by flooding that area with water. Hopefully the fire is on the opposite side away from the meter.

Most firemen, I believe, religiously respect electricity. They say it does not mix well with water, another perspective is that electricity mixes all too well with water.

I have had to respond to sites with firemen on site, standing off to the side, waiting for me to make something safe before they would proceed with their task, of course never been a raging fire.

Thanks!

I appreciate the use the main has on the outside by the fire department. Certainly even a home owner or renter could also throw it if an emergency happened inside without any danger to themselves from the electricity. I think it ought to be in the code, if for no other reason than what you have said.

Tom

It is code, like I said, if line is over ten foot, the main must be located outside.

I am re-wiring an old house. It is a small 2 bedroom, 1 bath house. We put in a 200 amp service and need to run a sevice entrance cable about 20 -25 ft to the inside breaker panel. My question is how big of a gauge wire should we run for the sevice entance cable. #? 3 conductor with ground in copper. We have 18 -110v outlets, 3 - 220V outlets (Window AC, Kitchen Stove and clothes dryer), 3 ceiling fans with lights, Electric bathroom heater in ceiling. Etc.
Thanks
You need to run #3/0 or 3ort which is the same term.make sure to mark your neutral,and that you wire the neutral correctly in the meter pan.

[QUOTE=war_animal]you need to run #3/0 or 3ort which is the same term.make sure to mark your neutral,and that you wire the neutral correctly in the meter pan.[/QUOTEthere has to be 3-#3 cables two hot and one neutral.

[QUOTE=war_animal]you need to run #3/0 or 3ort which is the same term.make sure to mark your neutral,and that you wire the neutral correctly in the meter pan.[/QUOTEthere has to be 3-#3 cables two hot and one neutral.
:o :rolleyes:

No I think he means a disconnect style meter socket.There is no real Code article that tells you when a situation requires a disconnect at the socket,I do know that we always used a disconnect type meter socket when the interior panel was located more than 8 feet from the socket.We also used disconnect sockets when the AHJ(the inspector)for the locality required it.Some do and some don't.OK using a disconnect style socket requires you to use SER style cable or 3 conductors and a ground wire conduit because it is illegal to have only one grounded wire on feeder circuit.You need a properly sized equipment grounding wire too on a feeder.To prevent ground loop current one must INSULATE the neutral conductor from the bare ground wire inside the secondary panel.. This is a must.It is also a good idea to drive a ground rod at the disconnect socket and tie the neutral and ground wires at the disconnect meter socket terminals to the rod and any other grounding electrodes that might be present.Okay now snappybob:this is how we do it.. We use NEC Article 220 Branch Circuit and Feeder Calculations.Okay you say you have a 200 amp required by the city.That pretty much tells you what size feeder cable you are going to use period.4/0 Aluminum SER style cable or 2/0 copper SER style cable or THHN wire in conduit.What we usually do derate the neutral wire (which must be white!)one size down so a nunk of 1/0 wire if you are going to usecopper.You will need #4 bare wire from the service disconnect breaker/meter socket combination to the ground rod but you and use #6 bare copper to the interior panel.Can you tell I have done my share of services?No matter what the panel all panelboards are limited to 42 circuits only.You will never find one with more tyhan 42 circuits,again that an NEC article.YOur interior panel is rated for 200 amperes and the rating shall not exceed 125% of 200 amperes continuous load.

No I think he means a disconnect style meter socket.There is no real Code article that tells you when a situation requires a disconnect at the socket,I do know that we always used a disconnect type meter socket when the interior panel was located more than 8 feet from the socket.We also used disconnect sockets when the AHJ(the inspector)for the locality required it.Some do and some dont.OK using a disconnect style socket requires you to use SER style cable or 3 conductors and a ground wire conduit because it is illegal to have only one grounded wire on feeder circuit.You need a properly sized equipment grounding wire too on a feeder.To prevent ground loop current one must INSULATE the neutral conductor from the bare ground wire inside the secondary panel..This is a must.It is also a good idea to drive a ground rod at the disconnect socket and tie the neutral and ground wires at the disconnect meter socket terminals to the rod and any other grounding electrodes that might be present.Okay now snappybob:this is how we do it..We use NEC Article 220 Branch Circuit and Feeder Calculations.Okay you say you have a 200 amp required by the city.That pretty much tells you what size feeder cable you are going to use period.4/0 Aluminum SER style cable or 2/0 copper SER style cable or THHN wire in conduit.What we usually do derate the neutral wire (which must be white!)one size down so a nunk of 1/0 wire if you are going to usecopper.You will need #4 bare wire from the service disconnect breaker/meter socket combination to the ground rod but you and use #6 bare copper to the interior panel.Can you tell I have done my share of services?No matter what the panel all panelboards are limited to 42 circuits only.You will never find one with more tyhan 42 circuits,again that an NEC article.YOur interior panel is rated for 200 amperes and the rating shall not exceed 125% of 200 amperes continuous load.
Well, you may have done your share of these, but much of what you write is incorrect.

There is a code telling that an outside disco is required. The one that says if the panel is too far into the structure, or a local code amendment. The inspector cannot request what has not been written. It's not his call.

"Ground loops" are not an issue in AC building wiring. Not sure where you got that one from.

It is not just a good idea to drive an electrode at a main disconnect. It is a requirement.

You do not need #4cu to a ground rod. A connection to just a ground rod requires no larger than #6cu. Also the correct size equipment ground from a 200A main disconnect to panel is #4cu.

The 42 circuit limit was lifted for the 2011 NEC cycle.

A continuous load is ABSOLUTELY NOT 125% of the panel rating.
A 200A panel is rated for 200A, and 80% of that for a continuous load, or 160A.

And lastly, you are addressing the OP like he is around to read and apply your advice. This thread is from 2005. I think it is a safe bet that this is all done by now. :rolleyes:

Tk Russel wrote "This system is usually two eight foot ground rods , spaced 6 foot or more apart, and a wire going the water system. If you have a water meter, the #6 wire may need to connect to both sides of the water meter to jump out the meter, so to speak."

This is incorrect... Sorry tk but the NEC requires that anything within 2/0-3/0 Copper or 4/0-500 kcmil requires a # 4 Copper wire for a grounding electrode to the water main only if such pipe is copper and in direct contact with the earth no less that 25'( usually you would just hook it up anyway and always jump the meter). Now the ground rods are okay to use with #6 copper wire and must be green or reidentified inside the panel or meter box.

Now to the service question a 2 bedrm house with 1 bath seems quite small for a 200A service. Now I don't know the demand of the house and maybe you want a Hot tub outside (which requires a 200a service) oR you have a lot of electric heat... But 9 times out of 10 an electrician will suggest a 200 a service to get the 17-1800 dollars (Massachusetts price) but in reality 100 or 150 a service will do just fine and also the sizing of the wire tk got it right a 4/0 SER aluminum cable is great and it depends on the disconnect. If it is 25' on the exterior of the wall and penetrating through the house the wire goes directly to the panel ( Usually 10' in wire length) there is no disconnect required. Copper for residential wiring is not needed considering we up here in mass feed 5 unit bldgs with 125 A Panles each with 500 KCMIL Aluminum wires and lasted for 10 years thus far no problems. Hope this helps

... But 9 times out of 10 an electrician will suggest a 200 a service to get the 17-1800 dollars....
No, they will suggest it because it makes little sense in today's world to install a new 100A service, or replace an old 100A with another 100A. Unless of course it is some kind of 800 sq/ft bungalow.
And it makes absolutely no sense to install a 150 when a 200 is only a few dollars more in material and NO different in labor.

Lastly, I feel sorry for you if you can only get $1700 for a 200A upgrade in MA. You are selling yourself short.

So I take it the meter can is 200 amp ready, the riser wire should be 4/O the se cable can probably be 2/O, a 150 amp breaker in the disconnect, and then 100 amp breaker in the pannel. That's a really weird code to retro-fit up too a 200 amp meter, but the city wants their moneys I guess... by the way don't forget your water ground!

Why don't people read all the posts??

This thread has gone from originally 2005, to 2008, to 2011, to Jan of this year. All with the OP not returning since 2005!