Yes, that was what I was getting at, if the insulation on the aluminum was nicked, I was thinking water and the elements could slowly corrode it to the point it couldn't handle a large load, but may work fine under a light load. But I was only speculating, I really don't have any real world experience with this potential scenario.
Troubleshooting residential
- Thread starter Ramman556
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
That's what happens with every compromised- or open-neutral condition: the voltage imbalance is dependent on the current imbalance.
kwired
Electron manager
- Location
- NE Nebraska
Seems to be much bigger issue with underground than with overhead wiring.
POCO's have bare aluminum ACSR for primary conductors and those take the elements as well as an ACSR bare grounded conductor on secondary lines. Connections need special attention but just exposing the conductor doesn't cause much for trouble as long as it remains in free air.
I agree with you, in fact the OP never said if it was a drop or a lateral. I was thinking service lateral in all my comments
kwired
Electron manager
- Location
- NE Nebraska
I've been finding and fixing underground faults for 35ish years. Other than when physical abuse happened such as excavating equipment hits a line or they drive a steel post into it, copper almost never has much problems, aluminum however oxidizes away until there is nothing left. You bad spot on aluminum is usually pretty obvious once you uncover the conductor, will be nothing but aluminum oxide where there once was aluminum.
My best guess is it starts deteriorating at the damaged spot in the insulation, keeps eating away at the conductor lessening the cross section at that area. Essentially making that spot a lot like a fuse link. As you add load it operates a little warmer, which also probably helps speed up oxidation at same time.
Can't say I ever run into situation where there is reduced volts because of resistance though. That "fuse link" still has relatively low resistance just can't carry as much current as the full sized conductor but has little linear length to it so not like reducing a 4/0 to a #10 for several feet, we just talking inches most the time which is no different than placing a fuse link in the circuit. These usually fail with no warning just like a fuse link would when it opens.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Fertilizer seems to eat aluminum up, I used cast aluminum bell boxes for driveway lights at a gas station, they were constantly spraying fertilizer on the grass, and after a couple of years, the boxes were basically dust! LOL! Probably what oxidizes the aluminum underground when it gets nicked.
Thanks, awesome perspective. I wasn't sure what the symptoms would be exactly. Didn't know if it would be like a fuse blowing, or a voltage drop.
ptonsparky
Tom
- Occupation
- EC - retired
You may have some low voltage with no load that drops again when you load it up.
kwired
Electron manager
- Location
- NE Nebraska
When that happens the conductor basically has already deteriorated all the way through, usually won't carry any significant load at all though. LED lights, those might work to some extent as long as total load is no more than maybe 50-100 mA.
Is that slang for a big load bank?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yep.
kwired
Electron manager
- Location
- NE Nebraska
I think there is a particular model or product line with that name.
Bad advice to call poco without doing due diligence while your there.
I have made many electricians look bad to customers because they called the POCO and didn't look quite far enough.
ptonsparky
Tom
- Occupation
- EC - retired
I agree, do not call them until you know the problem is on their side and/or you cannot do further testing without disconnect.
Then be there when they are.
A hand held hair dryer or milk house heater is all you need for load unless you want to see the connection smoke.
Little load bank. Goes in the base.
Hairdryer or heat gun works just as well.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I agree, check everything before you call.
But on the same token, I have made a few lineman look bad, when they have said nothing was wrong on their end when a customer had called them before me. When I show them the problem is beyond the customer side. That's usually because they only "looked" at a weatherhead connection, or transformer connection from the ground. When I showed them the measurements I took and where, they then will dig deeper and find it's one of their connections.
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