Residential electrical service

[Hv&Lv]

The power company I work for in Nevada 2/0 AL is the minimum conductor size for services. There should be an engineer you can contact at the company to verify their requirements

so you guys don't use #2 or 1/0 triplex?

 

[kwired]

so you guys don't use #2 or 1/0 triplex?

Or even #4 or #6 for some limited load services?

 

[dgutshall]

so you guys don't use #2 or 1/0 triplex?

We do have some smaller 50 amp services at rv parks with #2 if approved by engineering. As of this year they switched to 2/0 as the minimum conductor size. It does get extremely hot in the summer 120+ and we have a lot of new bigger solar systems being added. That is just here of course most likely different elsewhere.

 

[Hv&Lv]

We do have some smaller 50 amp services at rv parks with #2 if approved by engineering. As of this year they switched to 2/0 as the minimum conductor size. It does get extremely hot in the summer 120+ and we have a lot of new bigger solar systems being added. That is just here of course most likely different elsewhere.

Ok. Makes sense now. I was thinking ALL wire, OH included.

We use #2 for limited services, and basically the same chart for our UG services

 

[xformer]

Hi Augie,

That's what is confusing me.

The lineman seems to say the underground feed from the transformer to the meter is Duke property (meaning performing conductor sizing using the utility's codes), but I get the impression from the NEC the conductors are my scope and I have to basically use the above chart.

I think the reason is because the NEC tries to keep the "fire in the wire" on the outside of the structure. I have often explained to people that if the poco wants to run a 200 amp service with speaker wire they can. They are the utility and fall under different guidelines as been mentioned in other posts. They also might have different insulated conductors which allow for higher ampacity. Just my $.02

 

[dgutshall]

Ok. Makes sense now. I was thinking ALL wire, OH included.

We use #2 for limited services, and basically the same chart for our UG services

The city here actually requires it all to be underground now. We are in a long process of taking all the older overhead underground at our expense

 

[LarryFine]

A few years ago, I added a second 200a panel to a 200a residential service for a tankless water heater that required four 40a circuits. The POCO said the existing underground wires would not be upsized.

 

[kwired]

I think the reason is because the NEC tries to keep the "fire in the wire" on the outside of the structure. I have often explained to people that if the poco wants to run a 200 amp service with speaker wire they can. They are the utility and fall under different guidelines as been mentioned in other posts. They also might have different insulated conductors which allow for higher ampacity. Just my $.02

Overhead conductors are in free air and therefore do have higher ampacity as a general rule.

One thing that can be a problem is conductor length. Some POCO at times will have a customer on end of a long run of overhead and even though the size conductor they use is fine ampacity wise, it experiences some pretty noticeable voltage drop during starting of AC compressor or other motors.

 

[garbo]

Hi,
I'm in Orange County Fl. I wish to upgrade my main panel (outside next to the meter) from a 125 amp to a 175-amp service.
The service entrance cable from the transformer to the meter is 1/0 aluminum direct burial cable (60-foot transformer to meter).
The power company's lineman that verified the size tells me that should be fine for a 200-amp service.
(I have an EC license (inactive) but I'm an automation guy and not familiar with all the codes involved.)

Trying to calculate from the code it seems like I will be limited to somewhat less than a 200-amp service.
When I hire an electrical contractor to do an upgrade. what is the maximum service the EC's engineer is going to allow on this existing 1/0 alum cable?
(Power company has approved a 200-amp service as far as the load on the transformer)

Andy

Unfortunately the Ultility companies do not have to follow the NEC and almost always underside their wires. I installed a 100 & 200 amp service in a hundred foot long 3 story downtown building that was feed with 60 year old rubber & cloth #6 gauge copper wire. This size wire is generally only good for 60 amps . They refused to replace the wire saying its the correct size because being its an underground service the dirt keeps it cooled. Never came across a panel with a 175 amp main circuit breaker so would go with a 200 amp service.

 

[hillbilly1]

I changed a service out many years ago, on a store that had a 400 amp single phase service. They were doubling the size of the store out the back, so the existing service was dug up and temporarily moved out of the way. 4/0 aluminum with 400 amps on it.(service was amazingly balanced) Voltage would drop to 100 volts at peak load. Wire was toasty warm! Changed the service to 1200 amp single phase, (owner did not want to pay for three phase gear) poco wanted to just do parallel 4/0 to the new service. Met with the engineer, and got him to upgrade to three parallel 350 kcmil.

 

[garbo]

I changed a service out many years ago, on a store that had a 400 amp single phase service. They were doubling the size of the store out the back, so the existing service was dug up and temporarily moved out of the way. 4/0 aluminum with 400 amps on it.(service was amazingly balanced) Voltage would drop to 100 volts at peak load. Wire was toasty warm! Changed the service to 1200 amp single phase, (owner did not want to pay for three phase gear) poco wanted to just do parallel 4/0 to the new service. Met with the engineer, and got him to upgrade to three parallel 350 kcmil.

You were very lucky to get them to upgrade thier wires. I installed a 800 amp three phase service where I tried arguing with PECO ( Now a part of EXELON ) . They only used 4/0 aluminum to feed the 800 amp service and to add insult to injury they tapped off a pole transformer that already had a 200 & a 600 amp service. Of course the pole transformer burnt out within a month or so and same undersized replacement transformer think only lasted 6 months. They told me that it cost them a lot of money to energize transformers but told them injection molding shop that had the 800 amp service runs 24/6 and the place with the 600 amp service ran 16/6.

 

[hillbilly1]

You were very lucky to get them to upgrade thier wires. I installed a 800 amp three phase service where I tried arguing with PECO ( Now a part of EXELON ) . They only used 4/0 aluminum to feed the 800 amp service and to add insult to injury they tapped off a pole transformer that already had a 200 & a 600 amp service. Of course the pole transformer burnt out within a month or so and same undersized replacement transformer think only lasted 6 months. They told me that it cost them a lot of money to energize transformers but told them injection molding shop that had the 800 amp service runs 24/6 and the place with the 600 amp service ran 16/6.

The owner wasn’t backing down, he was blowing at least one to two ballasts a day. They did blow the transformer a couple of months after the service was energized, which was during the summer with all of the A/C’s kicked on. That transformer also had the owners house ran off it.