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Old 03-04-2009, 04:47 PM   #1
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Underground 240v single phase residential supply


I am posting this thread as I am getting conflicting information from members and it is probably my failure to give the facts correctly. So here are the facts:
I live in RURAL Northern CA and our power company is going to provide a Power drop to my Pole.
It is my understanding that they will terminate their steel lines to my pole head, which they will connect to my copper conductors running inside the 2" conduit which runs up the to the pole head connecting to my meter which THEY will insert after a "County sign off" into the 200Amp-8 space-8 circuit Outdoor meter breaker which I have set next to the pole.
I then have a 185ft trenched 3" conduit leading to the utility room which houses the 225A Main Lug loadcenter.
I have been told for that distance at 200A service I will need 4/0 copper.

My question is how many conductors and what size do I run through the 2 inch conduit running up the pole to the what ever its called, where I will get the 'hand off' from the Power Co and how many conductors and what size do I need to run through the conduit to the Main lug loadcenter 185 feet away( from the meter on its pedestal.
Given that I get termination at the pole head then my total distance will be 185ft plus 25 feet pole to pedestal so total is now 210 ft. Perhaps this will mean even bigger Cu size than 4/0 though it seems crazy not to mention $$$$
Any help much appreciated.
Thank you
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Old 03-04-2009, 05:00 PM   #2
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Underground 240v single phase residential supply


Quote:
Originally Posted by DIYALLTHETIME View Post
I am posting this thread as I am getting conflicting information from members and it is probably my failure to give the facts correctly. So here are the facts:
I live in RURAL Northern CA and our power company is going to provide a Power drop to my Pole.
It is my understanding that they will terminate their steel lines to my pole head, which they will connect to my copper conductors running inside the 2" conduit which runs up the to the pole head connecting to my meter which THEY will insert after a "County sign off" into the 200Amp-8 space-8 circuit Outdoor meter breaker which I have set next to the pole.
I then have a 185ft trenched 3" conduit leading to the utility room which houses the 225A Main Lug loadcenter.
I have been told for that distance at 200A service I will need 4/0 copper.

My question is how many conductors and what size do I run through the 2 inch conduit running up the pole to the what ever its called, where I will get the 'hand off' from the Power Co and how many conductors and what size do I need to run through the conduit to the Main lug loadcenter 185 feet away( from the meter on its pedestal.
Given that I get termination at the pole head then my total distance will be 185ft plus 25 feet pole to pedestal so total is now 210 ft. Perhaps this will mean even bigger Cu size than 4/0 though it seems crazy not to mention $$$$
Any help much appreciated.
Thank you
Are you on the 2008 code cycle?
If so, you need a 4 wire feed. If not, then you MAY be able to get away with a 3 wire feed. However, the 4th wire we are debating about is going to be a 4awg copper per nec 250.66. 200 feet of 4awg, less than $1 per foot. My strong recomendation, for the cost, ($300 for a 500' roll of 4awg wire), Just run the ground and be done with it. You will (may) need additional 4awg wire for bonding things like your water pipe to your electrical service, gas pipes, ufer ground. You will need to connect ground rods at each structure as well, 6 awg can be used, but just buy a spool of 4awg, and use it for your panel ground as well as for your ground rods and other grounding needs.

Per NEC 310.14(b)(6) for 225A service you need 2/0 copper. This does not take into account voltage drop, you will likely want to upgrade in size to account for the distance. Going up to 3/0 will more than likely be completely adequate in the real world unless your planing on running a very heavy close to maxed out load all the time. (are you going to run one of those monster instant electric water heaters, or a huge heat pump?, if so, consider 4/0, I think larger is unnecessary, some may disagree)

The 2 hots and the neutral should be the same size (some cases allow the neutral to be smaller, but I would check with your inspector before downgrading the neutral size at all, I am not sure if this is directly addressed in the nec or not.) , the ground, as I stated needs to be no larger than 4awg.

Does that help with some of the confusion?

Jamie
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Last edited by jamiedolan; 03-04-2009 at 05:05 PM.
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Old 03-04-2009, 06:07 PM   #3
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Underground 240v single phase residential supply


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Originally Posted by jamiedolan View Post
Are you on the 2008 code cycle?
If so, you need a 4 wire feed. If not, then you MAY be able to get away with a 3 wire feed. However, the 4th wire we are debating about is going to be a 4awg copper per nec 250.66. 200 feet of 4awg, less than $1 per foot. My strong recomendation, for the cost, ($300 for a 500' roll of 4awg wire), Just run the ground and be done with it. You will (may) need additional 4awg wire for bonding things like your water pipe to your electrical service, gas pipes, ufer ground. You will need to connect ground rods at each structure as well, 6 awg can be used, but just buy a spool of 4awg, and use it for your panel ground as well as for your ground rods and other grounding needs.

Per NEC 310.14(b)(6) for 225A service you need 2/0 copper. This does not take into account voltage drop, you will likely want to upgrade in size to account for the distance. Going up to 3/0 will more than likely be completely adequate in the real world unless your planing on running a very heavy close to maxed out load all the time. (are you going to run one of those monster instant electric water heaters, or a huge heat pump?, if so, consider 4/0, I think larger is unnecessary, some may disagree)

The 2 hots and the neutral should be the same size (some cases allow the neutral to be smaller, but I would check with your inspector before downgrading the neutral size at all, I am not sure if this is directly addressed in the nec or not.) , the ground, as I stated needs to be no larger than 4awg.

Does that help with some of the confusion?

Jamie
Jamie, thank you so much for your reply, I called the Building Dept half an hour ago and apparently I CAN go with three wire all same size, two hots one neutral and in addition ground the Outdoor meter breaker with Cu Rod and also ground the Main Lug loadcenter with a 2nd Ground Rod.
So it seems as though the ground will not be needed within the conduit with the other conductors?
BUT he said for the 210 feet run from the hand off at the weatherhead on top of the pole to the Main lug loadcenter that for the proposed 200A service it called out 250kcmil wire.
Huge I know, but unless I can find an electrical engineer to sign off on a smaller wire size I will probably have to go for a 125A service as this was calculated out at 1/0 copper.
I will have No forced air heat in the home or Air con, Propane will heat water and cookstove top. The only Big Amperage draw item being a steam generator 50A plus a Sauna 40A ( run separately) Electric oven, Fridge Dishwasher regular lighting and circuits for light use appliances.
What do you think on the wire size?
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Old 03-04-2009, 06:30 PM   #4
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Underground 240v single phase residential supply


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Originally Posted by DIYALLTHETIME View Post
Jamie, thank you so much for your reply, I called the Building Dept half an hour ago and apparently I CAN go with three wire all same size, two hots one neutral and in addition ground the Outdoor meter breaker with Cu Rod and also ground the Main Lug loadcenter with a 2nd Ground Rod.
So it seems as though the ground will not be needed within the conduit with the other conductors?
BUT he said for the 210 feet run from the hand off at the weatherhead on top of the pole to the Main lug loadcenter that for the proposed 200A service it called out 250kcmil wire.
Huge I know, but unless I can find an electrical engineer to sign off on a smaller wire size I will probably have to go for a 125A service as this was calculated out at 1/0 copper.
I will have No forced air heat in the home or Air con, Propane will heat water and cookstove top. The only Big Amperage draw item being a steam generator 50A plus a Sauna 40A ( run separately) Electric oven, Fridge Dishwasher regular lighting and circuits for light use appliances.
What do you think on the wire size?
This is a dwelling right...

200A service: 2/0 CU or 4/0 AL
225A service: 3/0 CU or 250 kcmil AL
This is on table 310.15(b)(6) unless CA amended this out of their code...

Volt drop does not need to be calculated per NEC but it does recommend only allow 3% volt drop.

Do yo have a metal water pipe, or is it PVC
If you have a metal underground water pipe this needs to be bonded to the grounding system, and will replace one of you ground rods.
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Old 03-04-2009, 07:30 PM   #5
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Underground 240v single phase residential supply


Quote:
Originally Posted by DIYALLTHETIME View Post
Jamie, thank you so much for your reply, I called the Building Dept half an hour ago and apparently I CAN go with three wire all same size, two hots one neutral and in addition ground the Outdoor meter breaker with Cu Rod and also ground the Main Lug loadcenter with a 2nd Ground Rod.
So it seems as though the ground will not be needed within the conduit with the other conductors?
It sounds like they are allowing you to run a 3 wire feed, so then you would just run hot, hot neutral. However, like I mentioned before, in the scheme of things, running the ground is a fairly minimal cost. But either way, you still need ground rods installed at every structure (including that first meter / panel post).

Quote:
Originally Posted by DIYALLTHETIME View Post
BUT he said for the 210 feet run from the hand off at the weatherhead on top of the pole to the Main lug loadcenter that for the proposed 200A service it called out 250kcmil wire.
Huge I know, but unless I can find an electrical engineer to sign off on a smaller wire size I will probably have to go for a 125A service as this was calculated out at 1/0 copper.
250kcmil is big, I had to look it up, it is 4 sizes bigger than 3/0. Have you asked them how they arrived at needing that large of a service when the NEC says that 2/0. is fine for 200A service?

I think 3/0 is around $3/ft X 3 wires X 210 feet = $1890. (so running a ground wire or not is going to be a fairly trivial part of the cost). You might want to consider running aluminum. It's not as malleable as copper, and needs a bit more care when terminating it, but it is often cheaper. You need to use a larger aluminum size than copper.

Quote:
Originally Posted by DIYALLTHETIME View Post
I will have No forced air heat in the home or Air con, Propane will heat water and cookstove top. The only Big Amperage draw item being a steam generator 50A plus a Sauna 40A ( run separately) Electric oven, Fridge Dishwasher regular lighting and circuits for light use appliances.
What do you think on the wire size?
I'd stick with 3/0 & 200A service (if they will allow it). If...

your baking a roast (40A)
run the steam generator (50A)
while dishwasher is running (15)
Lights & misc small appliances are on (25A)

With 125A service, your dancing around the tripping point, (above numbers estimates, but I think you get my point) I'd not want to be that close to maxing out my service.

Jamie
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Last edited by jamiedolan; 03-04-2009 at 07:36 PM.
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Old 03-04-2009, 08:54 PM   #6
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Underground 240v single phase residential supply


Dear Jamie
yes, it is a dwelling, a home and nothing more thank you so much for quoting the code, and, well I do not know if California has changed this code as it would certainly help me to find out, would you know where I could look.
As I have already purchased Outdoor Meter Breaker and Load center etc it would be nice to think I could get an electrical engineer to sign off this job on 3/0

Our Building permit is what they call here a Rural Owner Builder permit (ROB) it is not as stringent as city planning as many people are Solar and we all have our own Springs wells and take care of our own Septic and refuse etc.
Thank you for your time
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Old 03-04-2009, 09:08 PM   #7
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Underground 240v single phase residential supply


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Originally Posted by DIYALLTHETIME View Post
Dear Jamie
yes, it is a dwelling, a home and nothing more thank you so much for quoting the code, and, well I do not know if California has changed this code as it would certainly help me to find out, would you know where I could look.
As I have already purchased 200A Outdoor Meter Breaker and 225A Load center etc it would be nice to think I could get an electrical engineer to sign off this job on 3/0 Cu

Our Building permit is what they call here a Rural Owner Builder permit (ROB) it is not as stringent as city planning as many people are Solar and we all have our own Springs wells and take care of our own Septic and refuse etc.
Thank you for your time
Another stupid Q ... What advantage is there in running the #4 Ground along with the three conductors in the conduit to the house if the Meter panel on pole and Load center at end of conduit run are each grounded with a Cu Rod?
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Old 03-04-2009, 09:13 PM   #8
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Underground 240v single phase residential supply


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Another stupid Q ... What advantage is there in running the #4 Ground along with the three conductors in the conduit to the house if the Meter panel on pole and Load center at end of conduit run are each grounded with a Cu Rod?
What is your advice on the conductor specification that I will purchase as I see USE UEW and many others?
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Old 03-04-2009, 11:04 PM   #9
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Underground 240v single phase residential supply


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Another stupid Q ... What advantage is there in running the #4 Ground along with the three conductors in the conduit to the house if the Meter panel on pole and Load center at end of conduit run are each grounded with a Cu Rod?
A separate ground wire keeps a clear fault path for minor power surges, and appliance failures that may rely on a ground connection. The neutral can serve this same function, but it also carried your return current. It is thought it is safer to keep the ground (fault path) clear (no return current on it, it is a line only use as a ground).

Ground rods should be call lightning rods or something else, because the only thing they really are good for is to dissipate the energy for a very high amperage short or a direct hit by lightning.

Jamie
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Old 03-04-2009, 11:06 PM   #10
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Underground 240v single phase residential supply


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What is your advice on the conductor specification that I will purchase as I see USE UEW and many others?
You will want single strand, thhn / THXN or similar. USE / ser is normally like romex and is in a jacket, that is not what you want.

Jamie
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Old 03-05-2009, 06:27 AM   #11
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Underground 240v single phase residential supply


I did not read much of these threads at all. Too much info and too confusing.

I wanted to ask though. Why a disconnect on the pole?
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Old 03-05-2009, 09:25 AM   #12
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Underground 240v single phase residential supply


I haven't gone through all these post yet either. But I think I have the simple understanding of it.

1.) Your 210 feet from the point of connection to the utility.

2.) Your dwelling is set up on a utility 'distribution point' or farm pole. Meter is located on the pole with a 8 space service equipment rain proof panel located adjacent to the pole.

3.) A "feeder" is then ran from the service equipment to your home/dwelling to a mlo panel rated at 225 amps.

First thing is what was your load calculation? (see below) This should have been done to determine the minimum service your dwelling requires. the load chart shown is load calculation...using the optional method...this will give you a shot at the actual demand of your service. You size your feeder accordingly or you can size to anything above the calculation. The service entrance and feeder must be sized to the calculated load nothing more and nothing less.

If your load calculation is 150 amps slapping a 225 amp load center and running 225 amp rated feeder to it may be needless overkill and costly for no gain. My understanding is your guessing at 200 amps for the feeder.

Advice....don't guess

Second you say the local authority is allowing a 3 wire feeder soooo run a 3 wire feeder if your getting this information from your local codes people. They are simply following the outside feeder rules of article 225 and 250.32 for grounding and bonding. So don't worry about code cycles like 2008.

For a calculated 200 amp minimum service at 210 feet you need 3/0 copper or 250 kcmil aluminum allowing for a main service entrance and feeder with 3% voltage drop given the utilities stated point of service voltage. You will bond the neutral at both the service equipment and the dwelling panel. Keep things simple and run 3 conductors all the same size. Code will allow a reduced neutral but make the necessary calculation to determine its size.

Note: You are required to have a main disconnect at the dwelling... an mlo panel by itself will not get it.

Third go out to the service equipment by the meter.. how are you feeding the dwelling? .. with a breaker in that 8 space panel?.... and how big of a breaker is it or will it be? Will the service equipment handle the size breaker you will need for the main feeder?

Or are you using feed thru lugs at the service equipment?

Do you intend to feed other buildings from the service equipment out at the meter or a pole light or anything? If not there is no reason for this type panel and a stand alone disconnect with overcurrent protection is all that would be required. It must be sized to the service amperage.

I am assuming the service equipment has a main breaker in it?? Or it may be an mlo on a 6 disco rule.
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