Thread: Service entrance conductors, mismatched size at rthe mast head.

Good Afternoon,

What is the appropriate action when the wires coming from the transformer are smaller than the wires going to feed the main panel. For instance the wire going to the panel is listed on its sheathing as a 3/0 copper. The panel (fuse/edison base) manufacturers rating is at 200 amps the actual main fuses themselves cannot be seen nor is there any evidence of their ampacity rating and the wire coming from the T/F is smaller than a 3/0 and is stranded AL ...see pict

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The conductors coming from the transformer may be rated differently because they are out in the open air where heat can dissipate more readily.

To add to Johns comments, the conductors in the triplex are under the control of the power company and are sized using a different set of rules.

To add more .. the connection is not easily seen in your photo and that connection to the drip loop of the service entrance needs to be appropriate for al to copper. That connection in your photo is normally made by the power company. The triplex (service drop) from the transformer likely has a bare messenger wire with the two ungrounded insulated conductors wrapped around it. The bare stranded (messenger) is also serving as the neutral. It should all look similar to the attached drawing ( provided by google images).

Great info thank you very much. John, Jim and Roger.

So if there is a problem or concern with the conductors coming from the T/F, I could recommend that those issues be addressed by the City/County, or should I say by a licensed electrician and leave it to him/her to offer that recommendation?

Anything before the splice in Roger's diagram is the utility's responsibility - no one else has control or say over it.

Originally Posted by Eric Barker

Anything before the splice in Roger's diagram is the utility's responsibility - no one else has control or say over it.

Please expound further if you don't mind. Do you mean to say that if there is a problem with the utility side, there is no course of action. Will an electrician get involved.
What would you tell the client about corrective actions to the utilities side of the splice?

As the wires prior to the splice belong to the utility they would be the ones to handle any issues with them. What problem are you trying to address?

I would be more worried about the 19 or twenty 30 amp fuses in that panel. Than the wire coming from the transformer to the meter loop I do not really see a problem with.
I would call for further evaluation by a Qualified Master Electrician for just the fuses. Then let him handle any other problems found.

Originally Posted by Bruce Adams

I would be more worried about the 19 or twenty 30 amp fuses in that panel. Than the wire coming from the transformer to the meter loop I do not really see a problem with.
I would call for further evaluation by a Qualified Master Electrician for just the fuses. Then let him handle any other problems found.

Bruce,
That I did do...The majority if not all the wiring was undersized for the fuses. There was no labeling, a panel that the nameplate rating on it is 200 amps, a 3/0 (300 amps) copper coming into the panel and an unknown sized main disconnect. It makes me wonder what is being fed from the transformer on a 2/0 AL wire.
This is a 1970's home with wall space heaters, gas furnace electric a/c split, water heater, Dryer hookup and a stove with 1200sf living space if that.
Thanks Bruce, I agree with your statement

Originally Posted by Jim Port

As the wires prior to the splice belong to the utility they would be the ones to handle any issues with them. What problem are you trying to address?

Jim,
Just before the splice, where the wire has a bend in it, the sheathing is deteriorated enough to have caused cracking and has subsequently exposed the conductor in several areas within a 24" section of the wire. In some cases I have seen the messenger wire, as Roger calls it, has broken strands like it had been cut or rubbed enough to cause damage like cutting of the strands.
I have in the past recommended an electrician consult on avenues of correction. I sometimes want to give the client more to go on than just that.
Thanks

First, you want to note what/where (exactly) is the utililty co. responsibility and what is the responsibility of the home owner. Next, make sure to clarify what you are responsible to report/inspect. If there is a problem w/ the "utility side of things", for sure note that the utility should contacted to evaluate the situation. There you are covered and have helped the home owner.

Hey Dave, I think it's time to buy a new camera...those pictures are BAD!

Originally Posted by Robert Dalga

Hey Dave, I think it's time to buy a new camera...those pictures are BAD!

That inspection was where broke it. I was just looking at the posts for digital camera ideas. Yea it is a piece of junk. WW special. Any ideas, I'm game.

What I believe I see is a 3/0 CU (according to you) attached to a #2 aluminum triplex conductor as someone has stated. Here is where things get tricky. We ( I work for a power company full time) are not under the NEC for this wire. Any wiring from those connections back toward the meter is under NEC regulations. Wiring under the NEC must be calculated per article 220. There are derations taken into account in the load calculations for sizing the service entrance cables, along with the feeder and branch circuits. The power co. is regulated to a point under NESC. and takes into account conductor in free air, with further derations, along with the fact that very rarely, if ever will the residence pull 1/2 of the load that the service is sized for. If you think the insulation is cracked, or broken on the utility side, you can suggest that the homeowner call the utility and have a service tech. come look at it. If it needs to be replaced, chances are, it will be replaced with new #2 alum triplex.

Originally Posted by Tony Cole

What I believe I see is a 3/0 CU (according to you) attached to a #2 aluminum triplex conductor as someone has stated. ..(section removed by me)........... If you think the insulation is cracked, or broken on the utility side, you can suggest that the homeowner call the utility and have a service tech. come look at it. If it needs to be replaced, chances are, it will be replaced with new #2 alum triplex.

Thanks Tony, I appreciate the input.