Dumb electrical question of the day

[kpendlet]

Hello all,

I recently passed the electrical inspection on my shop and the power company has done their thing (installed a new transformer, trenched/buried cable, installed meter panel, etc.). Now I need to connect the meter panel to the service panel inside the shop. I have done a lot of wiring of nearly every type, but I have never messed with service cable. What cable do I need to buy and how do I connect it in the meter/service panels - pics would be awesome ? Thanks for indulging my ignorance.

 

[Charles (in GA)]

Cable rated as SE (Service Entrance) or one of several other ratings, of a size for the amperage you are running. I hope you use a combination meter and disconnect switch outside. You really should have had everything done before the code inspection, I'm surprised they passed you.

NEC Table 310.15(B)(6) specifies conductor size and type for 120/240V 3 wire single phase dwelling services and feeders. Here is the link to the exact same code book I am looking at. You want page 70-141

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=7005SB

You don't say if you are going some distance and will need a jacketed cable, or if the inside and outside panels are back to back with conduit connecting them. I put mine back to back and went to Home Depot and bought about six feet of the twisted "mobile home" cable. It is four wires twisted together designed for direct burial. One is smaller than the others and marked with a green stripe, the gound, and one will have a grey or white stripe on it, the neutral. If you have an outside disconnect switch, then you need to take four wires to your breaker panel and the neutral and ground bars must be electrically separated. If you do not have an outside disconnect and will be using the main switch in the breaker panel for a service disconnect, then you need to take three wires inside, the ground and neutral being one combined wire, and the two bars in the panel must be connected together.

Charles

 

[swgray]

Hello all,

I recently passed the electrical inspection on my shop and the power company has done their thing (installed a new transformer, trenched/buried cable, installed meter panel, etc.). Now I need to connect the meter panel to the service panel inside the shop. I have done a lot of wiring of nearly every type, but I have never messed with service cable. What cable do I need to buy and how do I connect it in the meter/service panels - pics would be awesome ? Thanks for indulging my ignorance.

Why would they inspect it before you've put the wiring in place? Even if the meter has a disconnect, don't they look at the wiring inside the building in
Georgia?

I have to have all the connections from the meter to the breaker panel and on to all devices before inspections are passed. Before the power company even think about getting power to the meter.

 

[kpendlet]

Why would they inspect it before you've put the wiring in place? Even if the meter has a disconnect, don't they look at the wiring inside the building in
Georgia?

I have to have all the connections from the meter to the breaker panel and on to all devices before inspections are passed. Before the power company even think about getting power to the meter.

Well, that's a good question. All of the wiring was in place inside of the building. The only thing that was not in place was the connection from the breaker panel to the meter. The county inspector not only passed my electrical inspection, but also gave me a C.O. before the power company even came out. He mentioned that thay normally don't issue a C.O. until after the power compnay does their thing, but in my case he did it. I guess he liked the what he saw. I'm sure that's not how it's normally done (I hope not), but that's what happened with me. I wasn't going to argue as my permit was about to expire.

 

[kpendlet]

Cable rated as SE (Service Entrance) or one of several other ratings, of a size for the amperage you are running. I hope you use a combination meter and disconnect switch outside. You really should have had everything done before the code inspection, I'm surprised they passed you.

NEC Table 310.15(B)(6) specifies conductor size and type for 120/240V 3 wire single phase dwelling services and feeders. Here is the link to the exact same code book I am looking at. You want page 70-141

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=7005SB

You don't say if you are going some distance and will need a jacketed cable, or if the inside and outside panels are back to back with conduit connecting them. I put mine back to back and went to Home Depot and bought about six feet of the twisted "mobile home" cable. It is four wires twisted together designed for direct burial. One is smaller than the others and marked with a green stripe, the gound, and one will have a grey or white stripe on it, the neutral. If you have an outside disconnect switch, then you need to take four wires to your breaker panel and the neutral and ground bars must be electrically separated. If you do not have an outside disconnect and will be using the main switch in the breaker panel for a service disconnect, then you need to take three wires inside, the ground and neutral being one combined wire, and the two bars in the panel must be connected together.

Charles

My panels are back-to-back. By outside disconnect do you mean breaker switches inside the meter box cover? If so, then that's what I have. However, in the inside panel the neutral and ground bars are combined. So I assumed that I needed 3 conductor service cable - 1 for each power bus and one for the neutral bus. Does this sound correct?

Thanks for the replies...

 

[swgray]

Well, that's a good question. All of the wiring was in place inside of the building. The only thing that was not in place was the connection from the breaker panel to the meter. The county inspector not only passed my electrical inspection, but also gave me a C.O. before the power company even came out. He mentioned that thay normally don't issue a C.O. until after the power compnay does their thing, but in my case he did it. I guess he liked the what he saw. I'm sure that's not how it's normally done (I hope not), but that's what happened with me. I wasn't going to argue as my permit was about to expire.

If there is a service disconnect at the meter it might not be too bad, I guess. If the meter is installed, it should also have power to it. That's not good, unless there is a disconnect.

Its best not to be playing with larger wires (or around them) while they're live. It's something called "arc flash", its also something I've seen discussed here.

A few links about it:
http://www.squared.com/us/services_support/squared_services.nsf/unid/4AC1B98211D7A2AA862570840068FA1A/$file/arcflashsafetyFrameset.htm

http://www.mt-online.com/articles/0204arcflash.cfm

http://www.alliantenergy.com/docs/groups/public/documents/pub/p015092.hcsp

 

[swgray]

My panels are back-to-back. By outside disconnect do you mean breaker switches inside the meter box cover? If so, then that's what I have. However, in the inside panel the neutral and ground bars are combined. So I assumed that I needed 3 conductor service cable - 1 for each power bus and one for the neutral bus. Does this sound correct?

Thanks for the replies...

3 conductors is correct. Do you have the ground rods in place an connected already? If not, you should get them in, too.

My previous reply took me awhile, I was checking the links to be sure they were still active.

 

[Charles (in GA)]

My panels are back-to-back. By outside disconnect do you mean breaker switches inside the meter box cover? If so, then that's what I have. However, in the inside panel the neutral and ground bars are combined. So I assumed that I needed 3 conductor service cable - 1 for each power bus and one for the neutral bus. Does this sound correct?

Thanks for the replies...

If you have a switch outside in the meter panel that disconnects all power beyond it, this is the SERVICE DISCONNECT. Leaving the load side of the SERVICE DISCONNECT will be the two hot wires (ungrounded conductors), the neutral (grounded conductor) and a separate ground wire. The Neutral, the ground wire and the bare #8 or #6 (depending on service amperage) solid copper wire (required by code) that goes to the ground rod(s) all meet at one point in the service disconnect panel. The "breaker panel" inside, is technically a "lighting and appliance panelboard" and will have a ground bar that is bonded to the metal box or housing and a neutral bar that is NOT bonded to the metal housing, and if it has a jumper strap over to the ground bar, it should be removed. This installation requires four wires, the two hots on the two lugs of the buss bars, a ground wire on the supply lug of the ground bar, and a neutral wire on the supply lug of the neutral bar.

For non-licensed DIY electrical types and even electricians, I HIGHLY recommend owning the following two books.

Charles Millers "Illustrated Guide to the NEC: Based on the 2005 National Electrical Code"

http://www.amazon.com/dp/1401850685/?tag=atomicindus08-20

and the National Electric Code of 2005

http://www.amazon.com/dp/0877656231/?tag=atomicindus08-20

You can, of course, purchase the NEC 2005 directly from the National Fire Protection Assn, www.nfpa.org if you wish.

Doing home wiring without these books is impossible I've concluded, and in many cases even professional electricians will give you incorrect info as the code has changed over the years and they may not be deeply familiar with the current code.

You can also consult the NEC at the following link. You wil not be able to copy, print, save or otherwise store the info you view, but you can at least read it, from the source. I recommend Miller's book as the code by itself is huge, confusing, and cryptic, Miller provides a through and detailed explaination of what the code covers in both residential and commercial installations. It is very useful in putting you into the right place in the Code itself to read further.

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=7005SB

Please note, I AM NOT a licensed electrician and the advise you have recevied here is worth exactly what you paid for it.............. notta.... zip.... nothing........ Don't believe anything you read on the internet unless you can confirm it from other reliable or accredited sources................

Charles

 

[Aceman]

3 conductors is correct. Do you have the ground rods in place an connected already? If not, you should get them in, too.

He needs 4 conductors, not 3. He has installed a meter main outside making the inside panel a subpanel. You must float the neutral. Where I live the grounding electrode system must be installed before you can get a service inspection.

Kpendlet, make sure to remove the jumper between the grounding and neutral bars. Also, there shouldn't be a screw bonding the neutral bar to the panel. If this panel is existing you most likely will need to separate your neutral and grounding conductors. The size of meter main breaker feeding the subpanel along with the subpanels buss rating will dictate your wire size.

 

[kpendlet]

He needs 4 conductors, not 3. He has installed a meter main outside making the inside panel a subpanel. You must float the neutral. Where I live the grounding electrode system must be installed before you can get a service inspection.

Kpendlet, make sure to remove the jumper between the grounding and neutral bars. Also, there shouldn't be a screw bonding the neutral bar to the panel. If this panel is existing you most likely will need to separate your neutral and grounding conductors. The size of meter main breaker feeding the subpanel along with the subpanels buss rating will dictate your wire size.

First, I want to thank all for the replies - it's very helpful and I appreciate all the comments. Secondly, Charles I agree that I need to do my homework and not rely on what I read here. However, based on what research I have done so far, the advice is pretty darn good.

I took another look at my breaker panel tonight and the power company must have removed the jumper between the neutral bar and ground bar - 'cause it ain't there anymore. You all were right about that. So, 4 conductors are needed - I understand that now. I guess the next step is refer to the book(s) mentioned before I attempt playing with something that can kill me. Thanks again.

 

[Junkman]

I would think that the very first thing that you need to do is see it they did complete the hook up to the pole, or just finished the preliminary work until you finish your side, and then they will come back and finish the hook up at the pole. I have seen where the power company will pull the wire through the conduit, and get everything set, but not do the final connection to the transformer until the meter socket is connected to the main panel. In your case where the meter socket has a disconnect below it, then they might have made the connection to the pole, assuming that you are competent to hook up the wires from the disconnect to the main panel. Personally, I hate putting my hands into any panel that is live. When I have to work on my panel in the cellar, I kill the power at the main disconnect at the meter, and then use a flood light that is running on my portable generator for light. I feel much safer knowing that if I were to touch a main lug wire, that my life isn't going up in smoke is a flash of a nanosecond. If they did make the connection at the pole, I am certain that they will come back and break the connection for you so you can safely hook the main disconnect to the panel. They don't want to see any one get electricuted.... especially a home owner doing his own work..

Since no one mentioned it, if you are using the aluminum cable, you have to put the black paste on it that prevents corrosion. Don't know what it is called, but they will know at the electrical supply house. The one that I use has small packets that will do about a half dozen wires. It is 50 cents a pack, and goes a long way. I like it because the big can will be lost by the next time that I need it....