Service entrance conductor

[Paul W. Abernathy]

lol........hard to understand when you say 120V and 80A.......

Always use 120/240 and Total Amps..lol

Also much easier to say in the original post...about the 500kcMil that it feeds (2) 200A panels for 400Amps...lol.....

In this case the 500 KcMil is very normal and seen almost all the time and installed in most cases by the POCO....we use Utly down here but I like the sound of POCO better..lol

[Jay Moge]

o.k..... call me IGNINT, but what's POCO?

[gmartin2]

Power Company?

[Jay Moge]

Originally Posted by gmartin2

Power Company?

oh......thanx.

[Doug Edwards, CMI]

Not to be confused with "Pogo" sage of the swamp.

[Bob Badger]

It has been mentioned but it bares repeating.

In my opinion HIs should not even concern themselves with service conductors under the control of the power company.

How do you know what conductors are under the NEC and what conductors are under the utility?

It has to do with the location of what is called the Service Point

Service Point. The point of connection between the facilities of the serving utility and the premises wiring.

Now for overhead services 99% of the time this service point is the splice at the weather head.

For underground services 99% of the time the service point is the line side terminals of the electric meter.

That applies even in areas where the electrician has to install the conductors from that meter to the utility.

BUT...each power company and state utility commission can have there own rules, the only way you can be 100% certain of the service point is to check with the Utility commission.

It is not unusual at all for the power company to run a conductor that is 50% the size of the conductor that the electrician is required to run.

DO NOT BE CONCERNED WITH THIS.

The power company knows what they are doing and if this smaller conductor under their control was to fail they will be out to fix it at no cost to the homeowner.

I installed an 800 amp service in a 30 unit apartment building, it connected to what I would call 200 amp power company service conductors, that was 15 or 20 years ago and as far as I know it is still fine.

How?

Easy, the 800 amp service in this building required by the NEC service calculations is grossly over sized. The power company knows this, they use demand histories to determine what will be sufficient.

[Jeffrey R. Pope]

Originally Posted by Bob Badger

In my opinion HIs should not even concern themselves with service conductors under the control of the power company.

When you're speaking of the size of the service conductors, I agree completely.

However, when we see deteriorated or damaged conductors, or conductors wrapped around tree branches (or other obvious safety concerns) we should certainly report the condition.

[Bob Badger]

Originally Posted by jpope

When you're speaking of the size of the service conductors, I agree completely.

However, when we see deteriorated or damaged conductors, or conductors wrapped around tree branches (or other obvious safety concerns) we should certainly report the condition.

Yes I agree, all safety concerns should be reported.

I guess my point would be is that the size of the power company's conductors is not a safety issue.

[Paul W. Abernathy]

lol....BOB...I see you have a new haircut..thehehehe....

[Bob Badger]

Originally Posted by pabernathy

lol....BOB...I see you have a new haircut..thehehehe....

Yeah, it fits my personality better.

He is also Tattooed on my shoulder.

[Paul W. Abernathy]

lol......

The comment on the 800A service is correct in that we see this all the time. Now take a new electrician in the field and they see this smaller 4/0 service coming down to a Aux. Gutter and then hiting a bank of meters and so on....and then the electrician ( green one mind you ) and walks in and sees the size conductors needed on the so called "OUR SIDE" of the job....they freak out....

Just takes time to understand them and know that POCO ( Utly ) work on their own rules and regulations.

[Timothy J. Gardner]

Bob,

An illustation to your overhead se cable size point.

tg

[Bruce A. King]

Some heat pumps cause some dimming of the lights when they first turn on.
This can be more noticeable at night for obvious reasons.

Some of the hvac makers have had complaints on this. It is many times due to long runs from the transformer to the house and even with 500 kcmil feeders.

Anyone have any good data on this surge current stuff?

[Bob Badger]

You already have the jest of it.

The instant power is applied to a motor you have what is called locked rotor current. All that means is the powers on but the motor is stationary.

The current immediately jumps, typically to about 6 times the full load amps. So if you have a heat pump with an FLA of 20 the starting load will be in the neighborhood of 120 amps. Unless the transformer is reasonably close you will see the lights dim for a moment till the motor is up to speed, the start up current drops almost as quickly as it rises. However incandescent lights are very sensitive to voltage fluctuations and our eyes are very good at seeing it.

The best, pretty much only fix short of moving the transformer is the installation of a 'soft start' on the heat pump. Instead of a contactor applying full voltage all at once a soft start will apply the voltage slowly which limits the high start up current.

Once you get into bigger motors 'across the line starts' are pretty much imposable as the start up currents effect the rest of the electrical system to severely.

The company I work for had to do a hard start of a 500 HP motor that had a FLA of about 525 amps so the Locked rotor would be in the area of 3000 amps. Long story short the power company paid us a visit and was none to happy with us. We effected good size area of RI.

[Greg Fretwell]

That service point picture does a good job of demonstrating the NESC side vs the NEC side. That looks like #2 triplex on the drop and 4/0 on the SE.
The #2 triplex is pretty much all you ever see on a dwelling here. It doesn't matter if it is a single wide trailer with a 60a service or a 4000 square foot McMansion.
FPL did a sweep 20-25 years ago and swapped them all out from the 3 separate strands on insulators. Everyone got the same thing.