Service Disconnect

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  #1  
Old 06-28-05, 01:15 PM
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Service Disconnect

When installing a new 125 amp service to replace an old service that doesn't have a disconnect, exactly what is the procedure?

There is an existing 2 breaker box (2-20 amp breakers) inside the wall directly below the meter. The wires from the meter enter this box thru a 3/4" metal conduit (about 12" long) and there is no disconnect that I can see. Apparently this service is 30 amps but I don't see any indication marked on the box other than the fact that there are 2 20 amp breakers.

Can I install a small 125 amp box with a 125 amp disconnect next to the existing box and then just have the Electric Utility bring in a new 125 amp service and connect it? How would the new service wires be routed from the new meter and what size conduit would be needed? Can the conduit be offset to join the meter and the new box, or would the service wires be routed straight down and then enter the new service panel from the side?

Or, would I need to totally remove the existing box and place the new box directly below the meter? Is this a job I can do - or do I need an electrician?
 
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Old 06-28-05, 04:49 PM
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There's pro's here who will give you the specifics, but I have done several service upgrades and a new service on the several homes I've owned over the years. It's not a simple thing.

The green book - "Wiring Simplified" covers the basics very well, but it is not complete and there are local regulations and power company requirements that may differ significantly. Rex Cauldwell's book, "Wiring a House" has an excellent treatment of the service entrance (IMHO).

My first steps have always been:

1. Contact the power company and learn what their requirements are for a service upgrade.

2. Contact the AHJ (issues building permits and conducts inspections) and learn what their requirements are for a service upgrade.

3. Get a couple of estimates from electricians.

Those three steps should help you determine whether or not you can do it yourself and whether or not you want to.
 
  #3  
Old 06-28-05, 05:00 PM
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Joe.Carrick,

Ok.....where to begin here....First, I will give my humble opinion and take it as you will...

I would replace the service because basically what you are saying is you are thinking of having a new service bought to the house to a new meter base...so many times they wont allow multiple meter bases on a single dwelling.

I would simply upgrade the entire setup and based on your questions I would say this is way over your head to try and attempt yourself without some knowledge of electricity...The simple headaches you will run into trying to get the project inspected could set you in a tail spin.

Now to answer SOME of your questions....

1.) If you are planning on installing a new panel you will want to install a new meter cab also. So you plan might be to subfeed the existing panel ( if possible as it sounds like it came over on the mayflower ) from the new panel but again depends ALOT on the existing panel as I am guessing as small as it is it is not set up to be a sub-panel and might possible have issues doing so.

2.) The question is does YOUR utility company install service to your meter cab...and is it underground or overhead. Are you going to be installing the mast or mast cap if you have overhead service or are they providing it because you certainly can't use what is existing for the new service.

Basically you will have to mount the meter cab on the side of the house and determine if YOU are responsible for the service either piping down or overhead and if overhead are you providing the mast or service head to the connection point?

Have you considered a 200A service versus a 125A service and what are you planning to add in the house that prompts you to increase the service...besides the fact the existing service is very small and I would venture is 70 years old..

Also your disconnects you don't see...are actually the circuit breakers itself in that old installation which is why you do not see a main.

Ok here is one of your questions:
Can I install a small 125 amp box with a 125 amp disconnect next to the existing box and then just have the Electric Utility bring in a new 125 amp service and connect it?
Well....unless you have a UTLY company willing to do more than the usual they will only bring the service to the meter cab and some don't even do that if it is overhead.....you will end up running the mast and service head and so on. Also the pipe being used now most likely will not be sized correctly for the 125A service you want to run so you will have to know what they are providing in order to size what you need.

So even at 1/0 AL which is fine for 125A service...and even if you ventured to downsize the Neutral (1) size...I would still suggest a 2" Rigid Pipe if the support is needed above the roof line...but I dont know that because we need all that information to be able to suggest something...if it is a side mount service head then you can run SE up....and in that case for the money I would simply run 4/0 SE up and put the 200A panel in again if not thru the roof and needing support for the service drop from the UTLY.

OK...alot of information and certainly not all you need as it gets more detailed in the process of grounding which probably is not correct on the older home anyway and you are probably NOT at all going to be able to use the existing meter cab on the house if it is older....you will certainly have to upgrade it....so again in my opinion...

Do an entire service change...you will be surprised it wont cost nearly as much as you think with only (2) circuits in the house and always get a few estimates and the lowest is NOT always the one to go with but in my opinion if you are not familiar with electrical wiring...no book from the mega supply stores will make doing a new service easy for the novice and also their is a time factor....

We usually do this in a matter of a day....cut the power in AM...inspected by 2PM and UTLY company back out to place meter by 4:30 and done.
 
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Old 06-28-05, 07:20 PM
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ElectricalMan,

I was hoping someone would step up eventually, and FWIW my mention of the books was merely a suggestion for Joe to study and understand the complexity of this undertaking, not that the information in any book could guide him through it. I hope I didn't mislead anyone.

You raised every issue that came to my mind (and chose to leave to the pro's) and then some. Your last points really hit the mark though, in my opinion. Safety and Time.
 
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Old 06-29-05, 05:16 AM
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rodek01,

naww....I thought your information was good and will aid in their learning. I certainly could not cover all the aspects of the service change but wanted to touch on the suttle things......
 
  #6  
Old 06-29-05, 06:58 AM
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Thanks for the info. I am pretty comfortable with electrical work, having installed subpanels and done all of the interior electrical work on a couple of homes myself. Working with a panel is not a problem, nor is the installation of a new mast for the overhead service.

I will plan on a completely new service adjacent to the existing with a new meter base and 125 amp panel. The house was built in 1957, so it's only 48 years old, not 70 but that's irrelevant.

Because of the property size and zoning restrictions, this house can't be expanded to more than about 1600 sq.ft. and because there are no major appliance loads - all that stuff is NG - I will not need a 200 amp service.

The existing circuits can easily be connected to a new subpanel at the current location, but this panel is relatively new and probably replaced an old fuse panel. It appears to have been installed within the last 5 years. As you said, it might not be suitable but if not it will be easy to replace.

I'll check with the Utility to determine what they need and go from there. Because we are going to be doing a facelift on the house, cutting the stucco to expose the exterior stud wall is not an issue and the installation of the new mast, meter base, main panel, ground, etc is not a problem. Everything can be done before the day of the changeover.

I might still have an electrician do it, but it's not really that difficult since all the major work can be in place before the meter is installed.

Thanks again for the info and suggestions.
 
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Old 06-30-05, 04:33 AM
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Joe.Carrick,

Sorry...the 70 year old joke was a inside joke since no breakers where around then I don't believe. Anyway, yes , if you can do this beside the original to the point where it is all complete except the final connections since you are redoing the wall anyway and can get into it then you would have an advantage certainly.

Turning the old smaller panel into a Sub-Panel is rather simple in that you are going to feed it from the new panel just want to make sure you are aware the wiring to it will need changing, any existing holes in it from the previous service plugged with approved methods and makeing sure the grounding complies to the updated requirements of today as many times older homes do not have a proper waterpipe ground and it is usually not sized correctly....

I certainly do not want to discourage you if you have the ability...not the intent of the post or forum at all . We just want you to be careful and understand all that pertains so that you can continue to post here in 1 piece....

Let us know how your project goes and best of luck.
 
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