Help! Residential underground splice failed

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newservice

Senior Member
A gereral contractor hired me to splice the ug service so he could build an addition. I used three Illco type splices approved for underground use on each side of the splice, 6 total.. Inspector passed it, poco hooked it up. Contractor then excavated perilously close to the buried conductors and built his garage addition, foundation, footer, poured floor etc.. Now 2 and a half months later, suddenly the home looses power on one leg. (single phase 3 wire.) Voltage on that leg is ~2vac to neutral, other leg is ~120. Have isolated failure to the section I replaced. So plan now is to dig it up, put a box for the connectors on one end, and rout the other directly into the meter.
Question: Is this likely a mechanical failure, or electrical, or both? May never know. I do know my faith in Illco splice kits is shaken, I very carefully torqued each one, made sure the sleeves were right for the moisture protection, etc. :ashamed:
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
A gereral contractor hired me to splice the ug service so he could build an addition. I used three Illco type splices approved for underground use on each side of the splice, 6 total.. Inspector passed it, poco hooked it up. Contractor then excavated perilously close to the buried conductors and built his garage addition, foundation, footer, poured floor etc.. Now 2 and a half months later, suddenly the home looses power on one leg. (single phase 3 wire.) Voltage on that leg is ~2vac to neutral, other leg is ~120. Have isolated failure to the section I replaced. So plan now is to dig it up, put a box for the connectors on one end, and rout the other directly into the meter.
Question: Is this likely a mechanical failure, or electrical, or both? May never know. I do know my faith in Illco splice kits is shaken, I very carefully torqued each one, made sure the sleeves were right for the moisture protection, etc. :ashamed:

Not sure which splice you used, but we have had these (figure1) in some places for more than 15 years with no problems.
You sure they were just shaken and not pulled too hard? Also, the splice could be just fine. A shovel nick in the insulation can cause another bad place in the wire inches from the splices.

http://www.ilsco.com/ProductsDetail...=hoiWcu0AVY7RNKMFKuLjJTPVqxe6Yr/d8hNzPPBi0ks=
 

newservice

Senior Member
That link comes up dead but they are the ones with the allen screws and the rubber plugs. Yeah I too think they were pulled on by a backhoe or something and seperated. I cant imagine that moisture caused them to fail in just 2 months but I will know soon enough. What Im wondering is should I just fix the fault, or redo the whole thing with a hand hole box right to the meter. If they are prone to failure Id redo it, but my first thought is they are fine as long as you dont abuse them by building within inches of them. thanks
Not sure which splice you used, but we have had these (figure1) in some places for more than 15 years with no problems.
You sure they were just shaken and not pulled too hard? Also, the splice could be just fine. A shovel nick in the insulation can cause another bad place in the wire inches from the splices.

http://www.ilsco.com/ProductsDetail...=hoiWcu0AVY7RNKMFKuLjJTPVqxe6Yr/d8hNzPPBi0ks=
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would bet it wasn't a failed splice. I suspect the cable was hit somewhere else. Good luck. Perhaps you can find someone with a cable locator.
 

newservice

Senior Member
I would bet it wasn't a failed splice. I suspect the cable was hit somewhere else. Good luck. Perhaps you can find someone with a cable locator.


Thanks Dennis, yeah locating it isnt a problem thankfully, its only about 40 feet and follows the footer of the foundation perimeter quite nicely unfortunately. Last time Ill let the GC talk me into that. Next time it goes far far away. Despite his promises you know darn well as soon as youre gone they are spinning delivery truck wheels on it, etc etc. Would hope it isnt a failed splice, that will sort of exhonerate me. Anyone else have experience with these splices? And they didnt specificly say Approved for Service conductors, only approved for Direct burial, but whats the diff? 4/0 cables and 2/0 neutral.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Thanks Dennis, yeah locating it isnt a problem thankfully, its only about 40 feet and follows the footer of the foundation perimeter quite nicely unfortunately. Last time Ill let the GC talk me into that. Next time it goes far far away. Despite his promises you know darn well as soon as youre gone they are spinning delivery truck wheels on it, etc etc. Would hope it isnt a failed splice, that will sort of exhonerate me. Anyone else have experience with these splices? And they didnt specificly say Approved for Service conductors, only approved for Direct burial, but whats the diff? 4/0 cables and 2/0 neutral.

I don't think the kit needs to state that it is suitable for service conductors. If it is suitable for direct burial then it would include some service cables as they are direct burial cables.
 

newservice

Senior Member
I don't think the kit needs to state that it is suitable for service conductors. If it is suitable for direct burial then it would include some service cables as they are direct burial cables.

Right! OK, just have to go dig it up and see what gives. Wish I did have one them cable locators that finds the length of the cables, like the Optical Time Domain Refractometer used in fiber. heh.
 

growler

Senior Member
Location
Atlanta,GA
Contractor then excavated perilously close to the buried conductors and built his garage addition, foundation, footer, poured floor etc..


Just make sure they are willing to pay for all this extra work. The contractor probably cut the cable and just cover it back up.


Something to think about. How old is this UG cable to start with? Some of that older cable used by the power company wasn't very good to start with. Some of it started to break down after 25-30 years and give lots of problems.


For a short run like that it probably would had been better to replace the entire run with new cable and sheeve with conduit. You have three splices in each cable but there is no telling how many other splices are in the cable from the past (if it's the old stuff ). I worry more about keeping a good neutral than anything else, you were lucky.
 

newservice

Senior Member
Just make sure they are willing to pay for all this extra work. The contractor probably cut the cable and just cover it back up.


Something to think about. How old is this UG cable to start with? Some of that older cable used by the power company wasn't very good to start with. Some of it started to break down after 25-30 years and give lots of problems.


For a short run like that it probably would had been better to replace the entire run with new cable and sheeve with conduit. You have three splices in each cable but there is no telling how many other splices are in the cable from the past (if it's the old stuff ). I worry more about keeping a good neutral than anything else, you were lucky.

Yeah for sure, he probly nicked it and now wants me to fix it. Already sayin stuff like shoulda done this right the first time . Not happenin. I agree probly better to replace that whole section, if its compromised in one spot theres probly others.
What I put in is new, and the existing was only 10 yrs old. We didnt want to go to the street cause would have to tear up driveway. I'll look into a cable fault locator, not familliar with them other than the OTDR.
 

Hv&Lv

Senior Member
Location
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Occupation
Engineer/Technician
Yes, that's exactly the one, the one on bottom left . You used these before with np then, right?

Correct. If these are the ones you used, I would look for a nick in the wire that has blown out. Like I said before, the bad place could be just inches from the splice. Utilities use these almost daily. In my experience, I have never seen one go bad, it is something else.

If you could find an earth return fault locator, it will pinpoint the fault.
 

kwired

Electron manager
Location
NE Nebraska
A gereral contractor hired me to splice the ug service so he could build an addition. I used three Illco type splices approved for underground use on each side of the splice, 6 total.. Inspector passed it, poco hooked it up. Contractor then excavated perilously close to the buried conductors and built his garage addition, foundation, footer, poured floor etc.. Now 2 and a half months later, suddenly the home looses power on one leg. (single phase 3 wire.) Voltage on that leg is ~2vac to neutral, other leg is ~120. Have isolated failure to the section I replaced. So plan now is to dig it up, put a box for the connectors on one end, and rout the other directly into the meter.
Question: Is this likely a mechanical failure, or electrical, or both? May never know. I do know my faith in Illco splice kits is shaken, I very carefully torqued each one, made sure the sleeves were right for the moisture protection, etc. :ashamed:

I have seen but never used the splicing devices you mentioned. You do have to make sure you use right splicing device sized for conuctor as well as overall conductor diameter. If it does not seal well enough around the conductor or if a cap over the set screws would come off you have a place for moisture to enter and especially if it is aluminum conductor, it will not last long. Same goes for if there is any nicks in the insulation not related to your splicing. "Scotchkote" is a good product to use on nicks. Tape alone on especially aluminum conductor does not do any good. If the contractors pulled something apart it would have quit working right away. If it has been working for 2-1/2 months since the excavation they did not pull anything apart but still could have done some damage and even taped it up or something thinking they would be ok with that.

Don't just go buy a buried cable fault locator unless you plan to use it a lot. You are not likely to find one for less than $2500. I have a used one that I got for much less but happened to be in right place at right time - it came from a POCO that no longer wanted it, and does have some age on it, but it works.
 

kwired

Electron manager
Location
NE Nebraska
I don't think those are direct burial. The one with the heat shrink is not the one on bottom left-- I may be wrong but...

Everything on that page is designed for direct burial. The heat shrink type kits are more forgiving as they have more range to them as far as making a good seal. The other types you must watch even more carefully to make sure the conductor is not too small to seal and also make sure the plug for set screw access is not lost or any plugs for unused ports.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Everything on that page is designed for direct burial. The heat shrink type kits are more forgiving as they have more range to them as far as making a good seal. The other types you must watch even more carefully to make sure the conductor is not too small to seal and also make sure the plug for set screw access is not lost or any plugs for unused ports.

Yep-- those look like polaris connectors and I did not think the polaris ones were rated for ug. Not sure how that is sealed because the page shows the conductors just sliding in as the polaris ones. Perhaps there is some silicone in the sleeve.
 

kwired

Electron manager
Location
NE Nebraska
Yep-- those look like polaris connectors and I did not think the polaris ones were rated for ug. Not sure how that is sealed because the page shows the conductors just sliding in as the polaris ones. Perhaps there is some silicone in the sleeve.

AFAIK they seal just because of tight fit - therefore careful selection is necessary - too loose of fit and you don't have a good seal.

I only use heat shrink products for underground sealing of splices. Never had a call back because of a failed seal on a shrink tube. Seen other products fail, seen heat shrink just inches away from another bad spot in conductors but never a heat shrink itself fail.
 

newservice

Senior Member
"Scotchkote" is a good product to use on nicks. If it has been working for 2-1/2 months since the excavation they did not pull anything apart but still could have done some damage and even taped it up or something thinking they would be ok with that.

.

The fill was very rough, no 2 inches of sand in the bottom of that trench. Am thinking now put it in pipe. Also, in the splice box that Ill be putting in, what type of connectors there? Thanks to all for the feedback very useful.
 

ceb58

Senior Member
Location
Raeford, NC
Yeah I too think they were pulled on by a backhoe or something and seperated.

Backhoes have a way of doing that. I will bet the bad spot is not in the splice but where they skinned the wire.

Yeah for sure, he probably nicked it and now wants me to fix it. Already sayin stuff like shoulda done this right the first time .

That's when I would go to his a** with a LARGE invoice when it is found someone else is to blame for the damage.
 
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