Power line going to workshop is too low?

[John K Jordan]

Have seen plenty of underground dug up for repairs. Takes awhile to find the problem, sometimes have seen the crew out for more than a month, was in early 2000's in a subdivision built in 70's. They have been in my subdivision a couple of times for repairs and adding extensions. Originally installed in the 90's. Don't lose power for very long, sometimes a large area.

My underground high voltage line blew out once. I was headed out to photograph a wedding when it failed and when I got back in a few hours they had made the repair and were filling in the trench.

underground_elect_repair.jpg

The utility had equipment that pinpointed the location. The problem actually was a pinpoint - I've got the short piece they cut out and spliced and the only thing visible is a tiny pinhole in the insulation.

JKJ

[Ben Helmich]

Honestly, underground utilities really should be the goal almost everywhere because they are significantly more resilient to weather events. I don't get it why aerial remains so prevalent in areas constantly whacked by hurricanes, etc., but the poles and wires just keep getting replaced over and over and over. In those areas, that's gotta already be costing more than burying them once and for all. Around here, it's trees that largely cause disruptions.

It’s waaaaay more expensive to do underground. This comes up in Houston after every hurricane. The good news is that the bad outages don’t happen very often. After Ike all the problem trees came down. It will take another 20 years or so for them to be a problem again. If two bad hurricanes hit close together, the second wouldn’t have the problem trees to blow over.

[Jim Becker]

Oh, I agree it's expensive to get the utilities underground. No question about that. At least relative to a short term decision. Longer term, especially with increasingly volatile weather patterns...the better play may be to suffer higher cost up-front to reduce cost (and outages) later. It's a balancing act.

[Travis Conner]

I think underground power is fine unless you live by the water. Everytime the water comes up on the land you can almost guarantee the power is going to go out. I guess it gets to those little transformer boxes sitting on the ground.

[Travis Conner]

Had an electrician look at it. He said it was fine since no traffic goes under it.

[Charlie Velasquez]

Had an electrician look at it. He said it was fine since no traffic goes under it.

Get the city inspector or Authority Havng Jurisdiction to check it, or take a pic with a length reference and take it in.

Just the fact that YOU can walk under it means that pedestrians can traverse under it. That and specs for attachment height for your masthead, including the drip loop means minimum of 10’.
I would not trust your electrician.

[John Stankus]

Honestly, underground utilities really should be the goal almost everywhere because they are significantly more resilient to weather events. I don't get it why aerial remains so prevalent in areas constantly whacked by hurricanes, etc., but the poles and wires just keep getting replaced over and over and over. In those areas, that's gotta already be costing more than burying them once and for all. Around here, it's trees that largely cause disruptions.

I can tell you exactly why. Cost. Back around 2003-2004 I was working in an advanced technology group at Nortel Networks. The ballpark was about $5 per foot aerial vs $100 per foot buried. This was for telecom infrastructure, power was probably a bit more.

At the time, I was the Nortel rep to one of the MIT Media labs industrial advisory boards and had quite the challenge of convincing them of the infrastructure cost to rewire (Install fiber) service to every home. The business models need to account for the real costs of the infrastructure. Some of this is why you see fiber installs going slow, and the innovation of shallowtrenching like google fiber is using. They did the shallow trenching in my neighborhood this summer. I can’t wait for the availability, since the copper plant is in such sad shape.

John

[Matt Day]

If it’s 7’ off the ground you’d be able to touch it, unless your less than 5’6”.

[Daniel O'Neill]

Seems like a good idea to go underground but it's really expensive. Additionally, all utilities on the pole have to go underground. Payback in our area is 33 years when resident pays a few thousand to switch their service. Air is an excellent at distributing heat away from the wires while dirt and pipes are not. Some larger duct banks actually have cooling. The companies definitely know the ROI both ways.


If humanity was good at long term thinking we'd have balanced budgets, but politicians & CEOs seem to think only about the next election and quarter. Not bashing not trying to be political just trying to surmise why a power company would not do something for their long term benefit. (put lines underground)

[Travis Conner]

I lived in a neighborhood with underground power, the power always went out just long enough to reset everything. Now I live in an area with what I believe is mostly overhead power lines and we don't have any of that bs. I don't see how underground power where lots of flooding occurs is a good idea.

[Jim Becker]

It's mostly about wind, Travis. Wind is the primary issue in the south and you add ice to that in the northern climates. I agree that underground has its own issues with things like flooding, but that "should" be accounted for in how it's installed. But we all know that best intentions are not always honored in that respect.

[Daniel O'Neill]

Sounds like the wire was going bad. Underground is subjected to a lot more moisture (water) in the conduit and will cause faults all over the place. If the wire is in conduit that is. Some of the old guys like to direct bury which allows for the splice Jordan had above but then the only way to fix a truly bad wire is to re-trench. 6 of one 1/2 dozen of the other. In a world where labor is usually the biggest cost, making it easy for the linemen to pull new wire fast via conduit is likely the way to go in most situations. Plus less yard/tree damage. Overhead has a lot of maintenance costs people don't see but certainly not conduit full of water Inside the transformers & vaults there is a gravel pit to try and dissipate that water and original civil engineering should mitigate 100 yr flood elevations so I'd say in most of the country you should be good. Additionally, underground wire is rated for wet locations. Also, wind as Jim mentioned & trees & birds & squirrels... and Kites that get loose. (We had to hire a helicopter to clear a 138kV line)

I lived in a neighborhood with underground power, the power always went out just long enough to reset everything. Now I live in an area with what I believe is mostly overhead power lines and we don't have any of that bs. I don't see how underground power where lots of flooding occurs is a good idea.

[John K Jordan]

Electricians have mentioned every underground conduit somehow gets full of water, no matter how well the conduit joints are sealed. Apparently water hurts nothing. The conduit is for protecting the insulation from physical damage.

[Travis Conner]

I live by the water now Jim and everytime we have a hurricane and the water comes up 4ft or so I can guarantee the power will go out. I'm not sure if the transformer (green boxes) are going under water or what, but they usually have it back on in 2 or 3 hours. I do believe their is a 240/120 transformer box right next to the bulkhead in my neighborhood so that means it's about 4ft above the canal. lol

[Frank Pratt]

Electricians have mentioned every underground conduit somehow gets full of water, no matter how well the conduit joints are sealed. Apparently water hurts nothing. The conduit is for protecting the insulation from physical damage.

That's what this electrician says too. The wire that's pulled in there is made for wet locations & in a hundred years will show no ill effects, as long as the insulation hasn't been damaged.

We had a 400A underground service feeder fail after just 3 years. It was 4 conductors of 750 MCM RW90 aluminum in concrete encased 4" PVC conduit. It's pretty big stuff; the wires are about 7/8" in diameter. What happened is that the guy drilling post holes for a garbage enclosure thought he's go ahead to do it without getting locates done. Then when the auger hit the concrete, he just kept pounding away at it until the tip of the auger went through the concrete, conduit, and pierced 2 of the phase conductors.

The conduit was full of water & 3 years later it did its job & the power went out. One of the conductors still had continuity, but was badly swollen & on its way out. The other had the insulation burst wide open & the aluminum strands had all turned to white powder. It was an expensive repair, with the feeder being 100M long and the restaurant was closed over a week because of it.

I saved that chunk of wire & keep it on my wall of shame in my office.