New 200 Amp Service

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  #1  
Old 10-09-11, 05:01 AM
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New 200 Amp Service

I have a question in regards to what wire is appropriate. Everywhere that I have researched tells me that 4/0,4/0,4/0,2/0 AL URD is the correct cable to use between the meter base and the building. I have a local electrician that is telling me that I can use 4/0,4/0,2/0 with number 2. Can anyone tell me which of the 2 is correct? There is a good bit of cost difference between the 2 and I want to make sure that it's done correctly. We are actually moving the service from the house to a pole so that it's easier to feed 2 other buildings. I have 3 runs, one is 80 ft, one is 65 ft, and the last is 25 ft. Thanks for any advice.
 
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Old 10-09-11, 07:05 AM
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4/0,4/0,4/0,2/0 AL URD
This would typically be correct for a 3 phase 4 wire wire service with no disconnect at the meter, the 2/0 being a reduced neutral, but if there is a disconnect, there needs to be an additional #2 ground.

I have a local electrician that is telling me that I can use 4/0,4/0,2/0 with number 2.
Assuming you'll have a fusible disconnect or circuit breaker at your pole, this could be correct for a single phase service. The 4/0s are hot conductors, the 2/0 being a reduced neutral and #2 being the ground. You could also use 4/0, 4/0, 4/0, #2. Personally, I don't like to reduce neutrals, but it is acceptable by code.

The above assuming aluminum conductors.

You didn't say, but I am assuming you are saying you want 200 amp service at each building, all fed from the pole. If this is the case, you'll need a service panel at the pole and not just a disconnect. A few more details about the distribution are needed. Is this just one 200 amp service, or 400 amp service, 600 amp or what?
 
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Old 10-09-11, 07:34 AM
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The 4/0, 4/0, 4/0, 2/0 could also be used as two hots with a full size neutral and a 2/0 grounding conductor.

I too would like to know more about this project.
 
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Old 10-10-11, 05:16 AM
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It will be 600 amp service at the pole with disconnects for each leg at the pole. My impression is that we will just come out of the meter base directly to each of the disconnects as a separate feed. Is a distribution device still needed with this? At each building there will be 200 amp service, that is correct.
 

Last edited by geewhz01; 10-10-11 at 05:19 AM. Reason: make correction
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Old 10-10-11, 11:13 AM
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Is this residential, commercial or agricultural? The #4/0 aluminum for 200A is only for a residential dwelling. Any other type of building needs 250 kcmil aluminum conductor to support 200A.
 
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Old 10-10-11, 12:27 PM
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It is indeed for residential.
 
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Old 10-10-11, 05:26 PM
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So....you are paralleling 3 - 4/0 Al conductors per leg to 3 disconnects. I hope your plan involves building a rack for the disconnects or it'll be a really busy pole. I think if I were going to do this, I'd install a 600 amp MLO panel with 1 - 600 amp main breaker and 3 - 200 amp breakers. Assuming you are using direct burial URD, I'd then run 4/0, 4/0, 2/0, 4 like this

4/0 4/0 2/0 4 x 500' Mobile Home Cable # 540-6800J by Southwire Company

Mod Edit: Joe made a typo. It should have been MCB not MLO.
 

Last edited by ray2047; 10-11-11 at 07:41 PM.
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Old 10-10-11, 06:08 PM
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Is this magnetic pick-up or a meter?
 
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Old 10-10-11, 06:25 PM
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Originally Posted by Justin Smith View Post
Is this magnetic pick-up or a meter?
Do you mean, a CT meter or a self contained meter?
 
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Old 10-11-11, 05:43 AM
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It will be a CT Meter.

So a MLO panel rather than separate disconnects? And yes the plan was to build a frame attached to the pole and put a 6X6 about 4 ft away to attach the frame to as well. But if you are saying I could do away with the individual disconnects and put just this MLO panel that sounds easier. Any idea of the cost or a good source for this panel?

Andy
 

Last edited by geewhz01; 10-11-11 at 05:48 AM. Reason: add mlo ?
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Old 10-11-11, 08:25 AM
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Originally Posted by geewhz01 View Post
But if you are saying I could do away with the individual disconnects and put just this MLO panel that sounds easier.
Yeah you can do it all with one panel. As long as there are no more than six disconnects it's okay.

Any idea of the cost or a good source for this panel?
Not cheap, and a local electrical supply house will be the best source. They can also help you with accessories you'll need for the panel like lug kits and hubs.
 
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Old 10-11-11, 07:31 PM
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So a MLO panel rather than separate disconnects?
I replied too quickly. I should have said a MCB panel with a 600 amp main circuit breaker. In my opinion, all residential services should have one main breaker, although it isn't always necessary to meet NEC requirements. If this were a commercial service, I'd go with the MLO panel. and 3 - 200 amp branch breakers.
 
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Old 10-12-11, 01:13 PM
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Just curious, what are you planning on running in the outbuildings that you need 200A per building.
 
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Old 10-13-11, 09:48 AM
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I run a server farm out of one of my buildings. It currently has 100 amps and we are pushing the envelope with it, hence upgrading it to 200. My local jurisdiction now requires 200 amp for new buildings, hence the reason the new building will have 200 amp and never use it.
 
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Old 10-13-11, 10:03 AM
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Now that changes the plan. Definitely do not use an undersized neutral at a data center; in fact it is worth oversizing it. Switching DC power supplies introduce harmonics on the neutral that can actually increase RMS current beyond what you would assume given a particular kVA load. You also might want to talk to the power company distribution engineer about swapping your transformer for a K-rated model which is designed to accommodate the harmonics from the computers.

I would also really encourage you to increase your conductors to 250 kcmil given that a data center is a continous load. Residential design guidelines and equipment are all based on a 80% continuous / 20% peak assumption that is not valid for a data center.
 
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Old 10-13-11, 12:58 PM
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No I don't plan on going with the 1/2 rated neutral, I just didn't understand why the electrician was recommending that. I'm not certain that ga power put a k rated transformer but they did come swap it about 3-4 months ago after I talked to the local engineer. I was having problems with the APC units telling me there was a under current problem off and on about every 5-10 minutes. It took some persuading but they did finally come swap it and the apc's have been happy every since. I've since picked up the 4 aught quad, still waiting on the local city electric to get back with me on a price for a mcb panel.
 
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Old 10-13-11, 01:07 PM
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Originally Posted by geewhz01 View Post
No I don't plan on going with the 1/2 rated neutral, I just didn't understand why the electrician was recommending that.
Most residential configurations would be just fine with the reduced neutral. Big loads like the air conditioner and water heater do not use it so it's usually safe to reduce capacity there to save a few bucks. However, the harmonics issue with numerous PC power supplies makes neutral size important.

It took some persuading but they did finally come swap it and the apc's have been happy every since.
Hopefully they put in a K-rated or at least oversized it enough to not overheat anymore.

If you can configure some or all of your UPSs or PDUs for 240V input, that will go a long way to keeping the load on the transformer balanced.
 
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Old 10-13-11, 05:54 PM
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It is indeed for residential.
In my area this would be a commercial installation. You might even want to consider running a super neutral and getting your service panel with a 200% neutral bar. If this is classed as a commercial service by the power company, you most likely will need a meter socket with a lever bypass depending on local power company requirements. This is not an NEC issue, but a usually a power company rules and regulations issue.
 
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