New electrical service in house.


  #1  
Old 05-09-07, 06:35 PM
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Red face New electrical service in house.

Hello folks,

My wife and I just bought our dream home after 3 years of searching and looking at a whopping 250+ houses. Now that we are in our abode, I have been thinking about adding a 3rd service onto our house. The upstairs has one 200 Amp service and the basement has a 100 Amp service. It looks to me like the downstairs was rented out before.

I am trying to add another 200 A service just to my garage. I have a ton of shop type equipment that I would like to run at home and I CAN, but right now I have a 20A circuit feeding the garage. Once my compressor, lights, and dust collector are all on... the breaker trips. Now THAT is annoying. I also have a welder that takes 100A @ 220V.

I have ran into a few setbacks though. For one, the power company will only run one drop onto a building here in WV. Multiple meters are not the problem, but putting a new drop on the other side of the house (while it would be very nice) will not be supported from the local power companies aspect. Which forces me to rethink my project a bit.

I want to do this correctly and I am not caring about the cost as long as it is done correctly and safely. (Don't get me wrong cost IS an issue, but I am able to do 90% of this myself.)

I guess I need some advice.

The current setup on the house has the old style ceramic connectors that bolt directly onto the fascia and side of the house. I want to upgrade this to a mast style connection. Does anyone know if I am putting multiple meter boxes on the house (there is already 2) if I have to put a mast for each meter, or do I just need one mast coming in?

Next question, because I will be running a cable from one end of the house to the other (about 120') Should I be using 4 oght or 2 oght for 200A? Also I am going to run the entire cable in 2" PVC conduit up the wall and through the attic into the garage. Is this the safest method to do this?

The plan that I have includes:

Changing out the current connection to a mast style connection, run the power cable through conduit through the attic, add a 200A disconnect outside of the meter box, upgrade the current 100A box to a 200A box, (including the incoming wiring). Are there any flaws to my thinking? I am looking for criticism here. I'd like to know what I'll be up against.

As a final note here, I have talked to the power company and the inspector and I was told that adding a 3rd power box would not be an issue.

Thank you for your time.

- Josh
 
  #2  
Old 05-09-07, 06:51 PM
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How a "service" is run is pretty much up to the local AHJ and the power company.

It is highly unlikely that either the AHJ or the power company will allow the service conductors to run through the attic. Service conductors are required to be protected by fuses or circuit breakers as close as practicable to where the conductors enter the premises.

I'm having a bit of difficulty envisioning your present arrangement and your proposed arrangement. If you could post some pictures on a photo-hosting site and post the URL here it would help.

Power companies in my area would charge separately for each meter and that includes any minimum and/or customer service charge. I think you would be better off with a single meter and connecting the various panels as sub-panels. One way, if you have the space for additional 240 volt circuit breakers in your existing 200 amp panel would be to have a 100 amp breaker serve the existing 100 amp panel and an additional 100 amp breaker to serve the garage/shop via another sub-panel.

Another way would be to install your mast and service conductors to a new 200 amp panel and from this feed the existing and proposed panels. The new panel would be considered the service and all the other panels would be sub-panels.
 
  #3  
Old 05-10-07, 09:02 AM
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It sounds to me like the project will actually involve combining the two existing services into a single 300A or 400A service with subfeeds to each of the two existing panels and one to the proposed subpanel at the garage. My personal opinion is that a 400A service is not a do-it-yourself job. For this part, I would recommend getting estimates electrical contractors.

All of this actually depends on a demand load calculation for house, garage and each existing panel. This calculation is used to determine how much of your present electrical capacity is used by the home and how much you can add (outbuildings, power tools) without overloading the service. This calculation can get complicated, but we can help you ballpark it if you're interested.
 
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Old 05-10-07, 09:26 AM
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If my understanding is correct, the new service equiptments will include three 200 amp meter-sockets, and three Service Dis-connecting Means, each rated at 200 amps.

The first concern is the ampacity of the Service Entrance Conductors, which are the conductors between the utilty connection and the meter-sockets.

You do not calculate the ampacity of the Service Entrance Conductors by the sum of the ratings of the Service Dis-connects, i.e., 200 + 200 + 200 = 600 amps. The calulation is done in accordance with relevant NEC Articles.

POSSIBLY 400 amps Service Conductors will be required, which for a single-phase Service is 400 MCM conductors, Table 310.15 (B) (6).It' s possible that the ampacity of the Grounded Service Conductor ( the "Neutral") can be a lesser ampacity because the 100 amp welder load do not impose a load on the Neutral, provided the reduction is Code-compliant.

Next is selecting a Wiring Method for the Service Entrance Conductors, which would be either a PVC or metallic raceway.

"Tapping" the 200 amp meter-socket conductors to the 400 amp (?) Service Entrance Conductors is best effected using a Metal Wireway, or "trough".

You will need to install a new Grounding Electrode Conductor which is best connected to the Grounded Service Conductor inside the wireway. The ampacity of the Service Entrance Conductors will determine the size of the GEC.

All of the metallic surfaces of the Service equiptments must be effectively "Bonded" together.

The three "Feeders" which extend from the "Load" side of the Service Dis-Connects must each include a Equiptment Grounding Conductor.

Please note I have not adressed any aspects of the installation of the Feeder Conductors, with the exception of the EGC's.

Good Luck, and Learn & Enjoy from the Experience!!!
 
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Old 05-10-07, 11:34 AM
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You don't need a separate meter for your garage unless you have some reason the bill that power separately. You only need a breaker in you main panel to feed the garage.
 
  #6  
Old 05-11-07, 06:55 PM
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Ok, I have pics:

See if you can get a better idea of WHY I want to do what I am talking about.

Joed - I weld headers and roll cages and also powder coat. I want this billedseperately so I know my usage for this so I know how to bill

I want to upgrade to a mast (because of the cleanliness and to update things properly)

I also have been told that the colored breaker panel and the smaller panel can be combined (which might be nice)

It IS a mess

:: Warning 56K users ::

http://s180.photobucket.com/albums/x...teKnight_2007/

Any thoughts on these pics?
 
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Old 05-11-07, 07:06 PM
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Sounds like it's time to call a licensed electrician. Changes will require a permit and inspection.
 
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Old 05-12-07, 09:38 PM
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Why not get a whole separate service to the garage with its own drop?


Yes, replace at least that Sylvania/Zinsco panel.
 
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Old 05-13-07, 04:30 AM
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I agree with ibpooks.

Do a demand load on the new feeder to the garage, and the existing home. Use those numbers to determine the total size serivice you need.

Have one large service installed then run feeders to sub panels where needed.

In this setup you can run the feeders to the garage in the attic space. Since they are not service enterance and will be protected by a fuse in the main panel.
 
 

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