Two runs of URD triplex in one conduit

[hotwiretamer]

Give me your pros and cons. Is it allowed at your Utility? Have you installed it without them knowing? Paralleled or for seperate loads?

[Pootnaigle]

Ummmmmm we only put one run in a single conduit. I spoze if it was temporary 2 would be ok. But we always just used one in each conduit.

[topgroove]

I've seen it done, but I think its a bad idea. In our line of work you always have to look out for the next guy. Someday someone might have to isolate it or repair it. All of our underground secondary is direct bury. We use duct going under roads and driveways and the individuall services are customer owned.

[duckhunter]

Seems like too big a chance for confusion. I guess if one were a run of 1/0 and one a run of 4/0 it wouldn't be a big deal.

[T-Man]

For a three phase secondary, you want to run all three phases in the same conduit so the EMF of each phase is balanced. (one cancels the other) On parallel runs running three "A" phases in one conduit for example would heat up and be a fire hazard. Each conduit should have an A B and C Phase in it.

If you ran two seperate single phase secondaries in one conduit the heat of one overloaded service could affect the other, if one burned up you would have to pull both to make repairs, as pulling one thru over another would be a nightmare.. . .not a good idea in my opinion

[heelwinch]

I don't see it as being an issue if it is a parralled service.... other than that i really don't see why it should be allowed.... unless maybe it's under a road where they have installed a sleeve for two houses or something along those lines.

[freshjive]

sh*t Groove! All direct buried? I work for the same company as you and we put all of our stuff in conduit and are pulling out most direct buried stuff as we move along..Some really old stuff from the old 2800 delta community that we ended up buying from the town in the early 80's is still out there, but very even very little of that now is direct buried. We had a 23kv sub-transmission line that was put in in 1971 go on us about 2 months ago, and wouldn't you know....Direct buried...It just seems like a very lazy way to run your wire..Easier, without a speck of doubt, but messy and innefective if you happen to get a pinhole and some water dribbling on it which will happen eventually if its direct buried...

[topgroove]

yeah I hear ya... If it was my choice every bit of URD would be in duct. with switch gear and powercons everywhere. But here in the west everything is direct bury except for three phase primary customers .What a pain in the ass it is to thump faults and dig up and splice. We still have a ton of submerceables, try troubleshooting them under three foot of snow:( how bout the non-loadbreak elbows:mad: Funny thing is there is never any rebuilds for all the crap in the ground here. Alot of stuff built back in the sixties is neglected and forgotten. flickering light calls are a pain too. we've got hand holes in the really old subdivisions that are only about a foot in diameter where you can bareley get the blocks out of the hole.

[topgroove]

Yep... about eight years ago we switched to primary that has that thick PE covering that covers the concentric. Before that we used the cable that had the concentric exposed. We've found that in some of the older URD developments the bare concentric is getting eaten away. God only knows what they used for fill in some of these places.

[hotwiretamer]

Yep... about eight years ago we switched to primary that has that thick PE covering that covers the concentric. Before that we used the cable that had the concentric exposed. We've found that in some of the older URD developments the bare concentric is getting eaten away. God only knows what they used for fill in some of these places.

We have been replacing direct buried unjacketed cable for years now with jacketed. If you have the ditch open, why wouldn't they want to throw conduit in it? Plastic is pretty reasonable!

[topgroove]

I totally agree... conduit is the way to go.

[T-Man]

Don't mean to poop on anyones parade, but if you have a cable in Plastic conduit and for some reason it faults in the tube. Do you pull in a whole new cable? How would you find the faults location if your Aqua Tronics or Ditch Witch harp can't see the current leaving the fault? If you use radar and find the fault that way. . .how do you cut into the duct not being able to test the cable de-energized first so you don't nick a hot line by mistake? Then once the cable fault is exposed, aren't you supposed to install a neutral bond before you cut the damaged cable so neutral current can pass without making you a path? How much conduit do you need to remove for that operation?
With all the directional Boring that is going on nowadays would conduit still be the answer?
Sorry, I'm "Old School" I like it in the ground where I can find and fix it, However I do like the newer jacketed cable to save the concentric neutral from going away.
But. . .. . alas. . . .I'm retired and this is of no big deal to this old cocker. . .LOL:D

[hotwiretamer]

Don't mean to poop on anyones parade, but if you have a cable in Plastic conduit and for some reason it faults in the tube. Do you pull in a whole new cable? How would you find the faults location if your Aqua Tronics or Ditch Witch harp can't see the current leaving the fault? If you use radar and find the fault that way. . .how do you cut into the duct not being able to test the cable de-energized first so you don't nick a hot line by mistake? Then once the cable fault is exposed, aren't you supposed to install a neutral bond before you cut the damaged cable so neutral current can pass without making you a path? How much conduit do you need to remove for that operation?
With all the directional Boring that is going on nowadays would conduit still be the answer?
Sorry, I'm "Old School" I like it in the ground where I can find and fix it, However I do like the newer jacketed cable to save the concentric neutral from going away.
But. . .. . alas. . . .I'm retired and this is of no big deal to this old cocker. . .LOL:D

Yes T-man, we do replace the whole run if it faults. If someone bores into it, or digs it up with a backhoe or what have you, we repair the conduit and replace the run. The company sends the contractor the bill for it! There is nothing worse than setting up to pull new cable after it has gone bad, finding out that somebody has put a splice in the cable and repaired the conduit. Those splices don't have a lot of tensil strength! Then there you are trying to find the spot in the conduit that was repaired so that you can fix it and pull in the new.

[MI-Lineman]

Don't mean to poop on anyones parade, but if you have a cable in Plastic conduit and for some reason it faults in the tube. Do you pull in a whole new cable? How would you find the faults location if your Aqua Tronics or Ditch Witch harp can't see the current leaving the fault? If you use radar and find the fault that way. . .how do you cut into the duct not being able to test the cable de-energized first so you don't nick a hot line by mistake? Then once the cable fault is exposed, aren't you supposed to install a neutral bond before you cut the damaged cable so neutral current can pass without making you a path? How much conduit do you need to remove for that operation?
With all the directional Boring that is going on nowadays would conduit still be the answer?
Sorry, I'm "Old School" I like it in the ground where I can find and fix it, However I do like the newer jacketed cable to save the concentric neutral from going away.
But. . .. . alas. . . .I'm retired and this is of no big deal to this old cocker. . .LOL:D

Yeah borin is great! Especially when they go through old abandoned fuel station tanks!:rolleyes: Or through an old concrete and re-rod dumpin ground! I've dug up more sh!t that was recently bored in then stuff direct buried or in conduit. We, which actually rarely happens, pull in new stuff through the conduit here when it goes bad.

Plus, have any of you noticed the new foam core conduit? If ya look at the end you can see a white line all around the middle? That bein the foam core! An excavator told me it doesn't support enough wait or isn't strong enough to hold up against frost heaving? BET IT'S CHEAPER THOUGH!:rolleyes:

[LEAFMAN]

We had two runs of 3/0 alum in one duct, one went bad and damaged all of them. If they were in seperate ducts, we might have been able to isolate the bad one and not dig it up at 4am in shitty weather. On new stuff we use seperate ducts.

[MI-Lineman]

I guess I would have to wonder though about 3 phase pad mounts and the conductor lengths??? We have to make sure all the legs are of equal length to prevent one from overloading so it seems havin more than one conduit on a parallel run would make it a little trickier no??

I've seen parallel runs direct buried burn each other up so what's the difference if it's in conduit? It'd be easier to pull out of a pipe than dig it up?

[hotwiretamer]

Ya, Parallel 3-phase runs in one conduit is probably a bad idea. I was just talking about single-phase. We will run parallel in one conduit when we need to upgrade the conductor size if the conduit is large enough. It beats digging up streets and driveways in a lot of situations.

[T-Man]

Ya, Parallel 3-phase runs in one conduit is probably a bad idea. I was just talking about single-phase. We will run parallel in one conduit when we need to upgrade the conductor size if the conduit is large enough. It beats digging up streets and driveways in a lot of situations.

I can see using conduit under streets and driveways even parking lots and patios, but a directional bore can also solve some of those problems if you have time to set up and get r done.

On service faults we needed to get back in fast, we would run coreflo with service wire in it, up a near by tree or light pole and over to the house with a staple under a shingle to tie off to and somehow turn the service into a temp Overhead to bridge the road or drive etc. You have to have the right conditions to tie off the temp but it would work where you needed to get the power back for a well pump, furnace in cold weather, or whatever in a hurry while a heavy crew could come in and make permanent repairs taking the time they needed to do so. We also used that "EZ Restore Transformer" we talked about in another Thread.

[hotwiretamer]

Here's what we use for temp driveway crossings:


3450

[Highplains Drifter]

I can see using conduit under streets and driveways even parking lots and patios, but a directional bore can also solve some of those problems if you have time to set up and get r done.

On service faults we needed to get back in fast, we would run coreflo with service wire in it, up a near by tree or light pole and over to the house with a staple under a shingle to tie off to and somehow turn the service into a temp Overhead to bridge the road or drive etc. You have to have the right conditions to tie off the temp but it would work where you needed to get the power back for a well pump, furnace in cold weather, or whatever in a hurry while a heavy crew could come in and make permanent repairs taking the time they needed to do so. We also used that "EZ Restore Transformer" we talked about in another Thread.


T-Man, I believe you have less faults when using an underground duct system. The conductor is not subject to rocks, gophers and tree roots. I see it used more in the “NO FROST ZONES” of the country. With places that have three foot of frost you would have to bury it as deep as the water lines.

[T-Man]

T-Man, I believe you have less faults when using an underground duct system. The conductor is not subject to rocks, gophers and tree roots. I see it used more in the “NO FROST ZONES” of the country. With places that have three foot of frost you would have to bury it as deep as the water lines.
In Wisconsin we have frost for sure but on average or according to spec. we bury secondary at 28" and Primary at 34" so frost is not much of a problem if everything is working right, easier to get to in frost if we have to. We are supposed to use bedding sand in the trench but not sure that is aways done. Common faults are dig ins, defective splices,and knicks in the cable jacket on installation which allows water and minerals to work on the aluminium causing it to disolve. Lightening can put pin holes in the cable and then the above will occur over time also. So a conduit would help but the cost of replacing a whole run of wire and a section of damaged conduit could be a good bit. And tearing up an older landscaped yard is heartburn for some customers and very costly to repair or replace.

This is a good discussion and I think it boils down to what philosophy each company takes. I think your method works for you and we adopt ours, neither is better, just what each company feels works for them and their customers. It shows the young ones on here that there are more than one way to skin that cat (sorry cat lovers that was not meant as baiting)

[Highplains Drifter]

Give me your pros and cons. Is it allowed at your Utility? Have you installed it without them knowing? Paralleled or for seperate loads?


Nobody has said what size duct they are installing two runs of conductor. I think the correct term for underground service wire is tri lay and quad lay where triplex is aerial conductor. Some utilities do not have their underground secondary and service conductors twisted or triplexed. I think the reason for this is to help dissipate the heat, also it is conducive if one of the conductors becomes bad one can pull out the bad conductor and pull in a new one. This is more cost effective then replacing the whole run.

[Highplains Drifter]

In Wisconsin we have frost for sure but on average or according to spec. we bury secondary at 28" and Primary at 34" so frost is not much of a problem if everything is working right, easier to get to in frost if we have to. We are supposed to use bedding sand in the trench but not sure that is aways done. Common faults are dig ins, defective splices,and knicks in the cable jacket on installation which allows water and minerals to work on the aluminium causing it to disolve. Lightening can put pin holes in the cable and then the above will occur over time also. So a conduit would help but the cost of replacing a whole run of wire and a section of damaged conduit could be a good bit. And tearing up an older landscaped yard is heartburn for some customers and very costly to repair or replace.

This is a good discussion and I think it boils down to what philosophy each company takes. I think your method works for you and we adopt ours, neither is better, just what each company feels works for them and their customers. It shows the young ones on here that there are more than one way to skin that cat (sorry cat lovers that was not meant as baiting)



With an underground system that is run completely in conduit one never places a splice in the duct. All wire pulls are from vault to vault and the conductors are terminated together in the vault or meter panel. The conductor goes directly from the reel into the conduit so there is less chances to have nicks in the jacket verses direct burial.

[hotwiretamer]

Nobody has said what size duct they are installing two runs of conductor. I think the correct term for underground service wire is tri lay and quad lay where triplex is aerial conductor. Some utilities do not have their underground secondary and service conductors twisted or triplexed. I think the reason for this is to help dissipate the heat, also it is conducive if one of the conductors becomes bad one can pull out the bad conductor and pull in a new one. This is more cost effective then replacing the whole run.

I'll be damned Highplains, I have to say that I've never heard the term "Tri Lay" or "Quad Lay". We have always just called it URD Triplex, or Quadruplex. We rarely use any form of secondary/service cable other than Try or Quad, always twisted.

Normally it is 4" for 4/0 or 350. We've managed to install parallel 4/0 in 3" in a pinch!!

We put single runs of 4/0 in 2" conduit for years, now engineering is calling for 350 on most jobs/upgrades. We install mostly 4" for our secondary these days, just in case we have to parallel later!

[Pootnaigle]

All we ever used was also twisted. But never to my knowledge did we ever run more than one run in any conduit.Standard size when I left was 2.5". services also had seperate conduit for each run,I've seen several with 3 or 4 runs thus 3 or 4 seperate conduits.Also when its a customer owned svc and is installed by the electrician they follow the same procedure, Ive seen as many as 6 all in seperate conduit and using large copper come up in a single transformer.I dont see any advantage to parallelling it in one conduit other than saving a few bucks on the conduit. It will elongate the outage for repair, possibly damage the other conductors, and make us say bad words when we realize whats gotta happen to fix it.

[T-Man]

With an underground system that is run completely in conduit one never places a splice in the duct. All wire pulls are from vault to vault and the conductors are terminated together in the vault or meter panel. The conductor goes directly from the reel into the conduit so there is less chances to have nicks in the jacket verses direct burial.

Drifter, all our underground conduit system downtown is exactly as you say here, We were talking about direct burial in the burbs being in conduit. . .or I thought that's what we were talking about.

[climbsomemore]

If you follow the NEC... Pipe fill is all about heat disapation. Pack a conduit full of wires and you can't get rid of the heat--- and the cable fails early.

Therefore... if 6 or 8 (or more) conductors will take up the correct amount of volume offered in a given diameter of conduit.. your ok.

I worked for a inside contractor many years ago... who estimated a lot of industrial work. He found that his costs and profits were better if he used smaller conductors in parrellel (stock items) than if he ordered larger conductors. To slash labor costs... he'd size pipe so he'd instal ONE large conduit instead of several to the same load.

The inspectors in that area always signed off on his work.

On the utility side.. we have pulled multiple singles into one large duct on manhole systems for years.

Service in pipe vs DB

If your frost line is deep... you will have a lot of wire frozen that cannot be removed from a conduit unless you can find a way to thaw it out.

From my experience... URD secondary wire just doesnt fault as often in pipe. Primary faults rarely damage the plastic conduit either... so once a replacement is called for one has to pull the old wire and pull new in.

Of course... a dig in will require withdrawl of the conductor and repair of the pipe.

Like a lot of other things in the electrical business how we do things is about balancing "how much it costs' with "electrically correct" vs the expected life span of the equipment. Every estimator or engineer can come up with a different "right" solution for any specific problem.

[MI-Lineman]

If you follow the NEC... Pipe fill is all about heat disapation. Pack a conduit full of wires and you can't get rid of the heat--- and the cable fails early.

Therefore... if 6 or 8 (or more) conductors will take up the correct amount of volume offered in a given diameter of conduit.. your ok.

I worked for a inside contractor many years ago... who estimated a lot of industrial work. He found that his costs and profits were better if he used smaller conductors in parrellel (stock items) than if he ordered larger conductors. To slash labor costs... he'd size pipe so he'd instal ONE large conduit instead of several to the same load.

The inspectors in that area always signed off on his work.

On the utility side.. we have pulled multiple singles into one large duct on manhole systems for years.

Service in pipe vs DB

If your frost line is deep... you will have a lot of wire frozen that cannot be removed from a conduit unless you can find a way to thaw it out.

From my experience... URD secondary wire just doesnt fault as often in pipe. Primary faults rarely damage the plastic conduit either... so once a replacement is called for one has to pull the old wire and pull new in.

Of course... a dig in will require withdrawl of the conductor and repair of the pipe.

Like a lot of other things in the electrical business how we do things is about balancing "how much it costs' with "electrically correct" vs the expected life span of the equipment. Every estimator or engineer can come up with a different "right" solution for any specific problem.

If you're close to a hot water supply and ya still got you're cooler on the truck that'll work! At least it did once but we had to be quick about it?:D

What I think you're sayin is if ya follow what the recommendations for how many conductors in a certain sized conduit is you'll be fine? If that's what you're sayin then I totally agree? That's all factored in to conduit sizin just look in the "Uglys!"

Where the hell you been anyways? Oops! Never mind that's off topic?:eek::o

[climbsomemore]

If you're close to a hot water supply and ya still got you're cooler on the truck that'll work! At least it did once but we had to be quick about it?:D

What I think you're sayin is if ya follow what the recommendations for how many conductors in a certain sized conduit is you'll be fine? If that's what you're sayin then I totally agree? That's all factored in to conduit sizin just look in the "Uglys!"

Where the hell you been anyways? Oops! Never mind that's off topic?:eek::o

We thawed a underslab run with a Hotsey Steam cleaner machine in Indiana one year... made a mess... just forced steamy hot water for hours intil the ice broke loose.
I have heard that you can heat steel pipe with live voltage... but hooking up 100 of 4" Ridgid to 120 volts and letting it cook seems iffy to me... my foreman swears they did it more than once.
Letting a "lineman" work in a steel mill was pretty common back when work was good....

[CHICAGO HAND.]

With an underground system that is run completely in conduit one never places a splice in the duct. All wire pulls are from vault to vault and the conductors are terminated together in the vault or meter panel. The conductor goes directly from the reel into the conduit so there is less chances to have nicks in the jacket verses direct burial.

Drifter, all our underground conduit system downtown is exactly as you say here, We were talking about direct burial in the burbs being in conduit. . .or I thought that's what we were talking about.

We have specs for duct splices. I have built a couple before. With a damaged cable and duct you make the splice and then repair the duct without having to pull out and in and then splice at both ends.

[hotwiretamer]

You have to use a specially rewired transformer to do it. I forget the connection right now but it is a similar situation to an arc welder. Actually an arc welder works to thaw metallic pipe. You can heat conductor with it but too much and the plastic insulation will melt.

You can use a transformer as an arc welder.

I'm sure glad I live in the desert. I never gave much thought about wire freezing in the conduit! That's definitly not a problem in the southwest. You guys are crazy for living in that frozen tundra!! I hate URD out here, so I know I would hate it twice as much in the winter there!!

[MI-Lineman]

I'm sure glad I live in the desert. I never gave much thought about wire freezing in the conduit! That's definitly not a problem in the southwest. You guys are crazy for living in that frozen tundra!! I hate URD out here, so I know I would hate it twice as much in the winter there!!

Why? If ya locate the fault fast enough the ground will be thawed where it's at makin for easy, sloppy, soupy, diggin!:rolleyes:

Actually it does suck!:o But it's a livin!!:D

[hotwiretamer]

I was in Arizona once in late October. It was over 100 degrees. I couldn't get enough water into myself. How the heck do you take care of a Deer, Elk or Moose in that temp??

The linemen had covers over the manholes trying to use an air conditioner in the vault. Does it ever cool off in Phoenix??

At least I can dress for cool weather for comfort. How can anyone stay comfortable at 110????

You get them HEAT STORMS there like in Cali??? Where damn near every transformer cooks the oil out?? :)

Worst thing I experienced was no rivers, at least normal blue ones. You have either gravel or raging brown torrents just looking for their next victim.


I guess all places have their attractors, Eh?

Sarcastic mode definitely used.

Actually we only deal with the extreme heat about 3 to 4 months of the year. The other 6 to 7 months it's damn nice!

I live west of Phoenix on the Arizona/Cal. boarder, right on the Colorado river. That river is actually still pretty blue! This time of year is a real bitch sometimes because it is extremely hot. Where I live hear in Lake Havasu our temps are normally warmer than Phoenix, in fact it is the hottest town in the state a lot.
We have summer monsoons that reak havoc on our system, but I can deal with the heat and a monsoon a lot easier than the cold. I guess everyone picks there own poison.
My hats off to you ice and snow lovers!

[hotwiretamer]

Here you go CL, proof not all rivers in Az. are "brown"!

The job sucked because it was URD, but the view never gets old:


3471

[Highplains Drifter]

Actually we only deal with the extreme heat about 3 to 4 months of the year. The other 6 to 7 months it's damn nice!

I live west of Phoenix on the Arizona/Cal. boarder, right on the Colorado river. That river is actually still pretty blue! This time of year is a real bitch sometimes because it is extremely hot. Where I live hear in Lake Havasu our temps are normally warmer than Phoenix, in fact it is the hottest town in the state a lot.
We have summer monsoons that reak havoc on our system, but I can deal with the heat and a monsoon a lot easier than the cold. I guess everyone picks there own poison.
My hats off to you ice and snow lovers!



I might have to stop by your house so you can actually show me how blue that river is! I tend to migrate towards the big Q…..:cool: