Service Entry Relocate-wire sizing questions

Users who are viewing this thread

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
Hi all,

I'm not an electrician, but have done a lot of electrical projects, including upgrading electrical services. So, a project of this size and complexity doesn't scare me. I am the homeowner and live in Wyoming and will be acquiring a permit from the state of Wyoming for this project (based on the adopted 2020 NEC). I've reached out to the inspector with my plan, and they are far less than cooperative.

The power company is supportive of my project and have offered 4/0-4/0-2/0 wire for free. But, I feel this wire size is significantly undersized and will result in a significant voltage drop over this distance. I'd rather purchase the correct sized wire and never regret it. This will be my forever house.

Attached is my design and my wire size calculations (L1, L2, N, and G). Does anyone have the skills to confirm my work? Or direct me to a place that can?

Many thanks!
 

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,412
Points
113
Location
IL
No attachment. 4/0 (0000) AWG is really big, so you must be going a long distance. If you are isolated from neighbors, would the electric company put the transformer close to your house?
 

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
Meter Base Relocate Project



Purpose:

The current power pole and associated mounted meter base and the pole guy wires are in the way and impede a recently constructed RV parking pad. I want to relocate the meter base to the edge of the property so it is out of the way.



Need:

I don’t need a stamped engineered design package. I’m simply looking for confirmation that my wire sizing/design is correct. Or, if they are not correct, what should the wire sizing be?



Questions:

  • What size of conductors (L1 and L2), neutral, and ground wire is needed for Alternative 1?
  • What size of conductors (L1 and L2), neutral, and ground wire is needed for Alternative 2?
  • Are there any other alternatives that would be viable while meeting parameters?
  • I’ll be using a direct bury wire. Would you put it in conduit as well?


Parameters and Design Criteria:


  • In the future, there will be a 100-amp branch service that will go to a future barn located either 450’, or 550’ or 670’ away depending on future selected build site. The 100-amp branch service may come off the meterbase or the 200-amp load center located on the southeast corner of the house.
  • There is an external main load center/breaker box on the southeast corner of the house. There are currently direct bury cables from the meter base on the pole that feed this which then in-turn feeds subpanels and circuits in the house. Similarly, the relocated meter base will feed this main panel.
  • The electrical service being relocated is 200-amp, single phase.
  • I want less than 3% voltage drop from meter base to house.
  • Underground service entry wires will be aluminum for cost savings.
  • Current actual voltage at the house as measured is 121 volts and 243 volts.
  • I will likely use 600V URD triplex aluminum wire with an added ground. RHH/RHW-2 XLP USE-2 cable is another option, but tends to be a little more expensive.


Alternative Service Entry Wire Routes:

  • Alternative 1 has a 200’ wire run that is direct from the new proposed location to a load-center/breaker box on the side of the house.
  • Alternative 2 has a 250’ wire run that heads northeast 40’ from the new proposed location then up the driveway to a load-center/breaker box on the side of the house.


My numbers:

  • Use 600V aluminum URD triplex wire with 350 KCMIL (L1 and L2) and 4/0 for neutral. This should cover either alternative wire route and still be under 3% voltage drop.
  • I figure the ground cable should be 1/0 aluminum to stay consistent with the NEC requirement to upsize the ground wire due to the oversized conductors.
Link to site layout picture: https://postimg.cc/qg5tMZXW
 
Last edited:

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
The site layout picture is in the link in the post above. I couldn't get a pic to post without an error? I downsized the file size too.
 
Last edited:

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
No attachment. 4/0 (0000) AWG is really big, so you must be going a long distance. If you are isolated from neighbors, would the electric company put the transformer close to your house?
The power company won't do that. This is a rural property, and they will only relocate a pole mounted transformer in-line with the current overhead transmission wire. Unfortunately, this will either put the new pole mounted transformer in the/my way or in a very small hay field/paddock that has livestock and would make it incredibly difficult to cut hay. As cush, the wire run will be 200-250 feet from the transformer/meterbase to the exterior load center on the southeast side of the house.
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Your questions can't be answered without an NEC load calculation. Even that will be an overestimate of the actual current on the service entrance conductors. If you size your 200A service conductors for 3% VD with 200A of current, you will be wasting money on aluminum.

Cheers, Wayne
 

Onokai

Member
Messages
128
Reaction score
11
Points
18
Location
Arcata,Ca
I can sugget at least a 200 amp home service panel and your barn will need anouther 100 amp service as a minimum . That 300 amp service and that a minimum. The load needs to be figured and the wire run -you can look up the 300 amps x length of wire run for your answer on google via the NEC code book.Oversize is always best-put it underground in conduit as well.
 

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
Thanks everyone. So, I did the load calcs. That was very good advice. Thank you. Here is the link to my load calculations. I think I'll be fine with a 200A service. So, what are your thoughts on both the service size and the wire sizes in my design layout?

Again, many thanks!

Load Calculations: https://postimg.cc/vxWgrRbb
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
On the load calcs:

- The loads that are not part of the dwelling unit, like the future shop, probably the RV pad and chicken/rabbit house, maybe the stock waterer, should not be part of the dwelling unit calculation. I.e. you don't get to use the 40% demand factor for loads above 10kW on those loads. [This is maybe a little bit of a gray area, where to draw the line between dwelling unit loads and non-dwelling unit loads.]

- So you need to do one load calc for the dwelling unit, and a separate load calc for the other loads, and add them together for your total service load. That's going to reduce your dwelling unit load but push the total service load over 200A.

- Say your load ends up as 150A for the dwelling unit and 120A for everything else, for an NEC calculated load of 270A. You could get a CL320 meter main with two 200A disconnect breakers, and use one for the dwelling unit, the other for the non-dwelling unit loads.

- But even in that scenario a reasonable number to use for voltage drop is going to be 150A or 200A. The service would never see 270A.

- For 200A @ 200', and 3% VD at 240V, 300 kcmil Al would be required. While for 150A @ 200', 4/0 Al would suffice. So you might just want to accept the free 4/0 Al the POCO is offering.


Cheers, Wayne
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
PS I think using conduit is likely a good idea for protection, although that may vary by local conditions.

So I would suggest paying now for an oversized conduit that would allow for future expansion, but accepting the free 4/0 Al the POCO provides. Then if you ever find that you have voltage drop issues or expand your needs, you can replace the 4/0 Al conductors relatively easily.

Cheers, Wayne
 

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
PS I think using conduit is likely a good idea for protection, although that may vary by local conditions.

So I would suggest paying now for an oversized conduit that would allow for future expansion, but accepting the free 4/0 Al the POCO provides. Then if you ever find that you have voltage drop issues or expand your needs, you can replace the 4/0 Al conductors relatively easily.

Cheers, Wayne
Thanks Wayne. All good info and advice. With the 300 kcmil AL wire, what size of AL ground would that require? Would it be a 1/0? Thanks again.
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
These are service conductors, right? So there's no EGC, just two hots and a neutral.

Cheers, Wayne
 

Onokai

Member
Messages
128
Reaction score
11
Points
18
Location
Arcata,Ca
I would take the 4/0 wire and oversize the condiut as Wayne suggested. The 2 200 amp panels sound right as well-they m,]ake 225 amp panels as well. I wish I had one as I have outgrown my 200 amp panel in 20 years
 

RLrobinhood

Member
Messages
46
Reaction score
0
Points
6
Location
Wyoming
These are service conductors, right? So there's no EGC, just two hots and a neutral.

Cheers, Wayne
Not technically service conductors. These will be conductors between the meter base at the edge of the property and the main panel on the side of the house. So, I believe I'll need to have a ground conductor and then bond at the meter base.
 

wwhitney

In the Trades
Messages
6,532
Reaction score
1,822
Points
113
Location
Berkeley, CA
Not technically service conductors. These will be conductors between the meter base at the edge of the property and the main panel on the side of the house. So, I believe I'll need to have a ground conductor and then bond at the meter base.
If it's a meter base only, no. But if it's a meter base with a breaker (meter main), then you are correct.

Cheers, Wayne
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks