What is your preferred method for laying cable in a trench? In Norway we use a chain with lift fittings, swivel, master link and operating chain. See it in this video : Although it not quite legal to lift like this with people hanging on to the drum to control the spinning it's the preferred method here. Will that be legal in the US? The reason for asking is that I work on a new tool that handles cable drums without any hands near the drum and in that case I wonder if there could be a market for it in the US.
Most of the cable put in around me is put in plastic pipe ,a lot is also incased in concrete
So then you are winching the cable through. And if its not going in pipes but directly into the trench as shown in the video, how do you normally do this? And I forgot to put a link to my new project, here it is: http://www.jack-pack.as/multigrab-general-info.html It's a drum handler that dont require any help from coworkers, it's operated by the excavator operator or crane operator all alone.
I would say it's been over 20 years since I've seen direct bury cable put in
Wow, is that the standard way of doing such a job in the US?
I live in a highly populated area,out in open country I don't know if they direct bury
Rarely do we put any direct bury in, most everything goes in conduit nowadays. I can only think of two jobs in the last few years I did with direct bury... 1. a 600' primary power trench where the owners wanted phone dropped in the same trench and the 3" conduit and 1 1200' secondary power trench that had armored triplex dropped in off the back of a truck with a 6' spool on it, they just drove alongside the trench and slid it in... a lot quicker(cheaper) than using a large tracked machine.
Nice setup with the swivel link Clue . In my area utility companies use Truck mount reel http://www.altec.com/products/cable-handlers/handler/rl9/ Trailer mount https://www.felling.com/trailers/public-utility-2/utilit-cable-reel-public-utility/ Dozer mount with plow . http://www.bronrwf.com/en/products/add-on-utility/specifications/static/hs-ii http://www.alliedsystems.com/News/cableplowing.htm
I have just finished a 3 D print prototype in a 1:10 scale, see it here:
Cable is defined as what? Here, voltage cable whether primary, or secondary needs protection from stones, or frost. SOP is a ditch, I use 46" deep. 6" of smaller than 1" goes under the conduit. It is covered with enough sand or crushed to cover 6" deep. typically this calls for 16" total sand depth. Then the ditch is covered. This yields 36" of cover above the conduit. Cable is pulled in with rope after excavation is covered. For this, we make do with human strength, or hydraulics to suspend a reel on an axle of aluminum conduit, I've used the same one for many years. To pull, we use either a capstan winch on a 1956 Power Wagon, or three or more people to pull. A rare project of communication cable is done direct burial, but I seldom see it in the past 20 years. A conduit can get cable replacement year round. Direct burial replacement in winter is a big ordeal. Willie
Sorry for my late reply, but I travelled to vegas for the conn/expo Well I'm not sure if I understand you guys correct. Are you pulling big sized power cables through a conduit? What about high power cables? Here we use conduit for the most with fiber optic cables. Some times we pull bigger power cables through a conduit when crossing a busy road, other than that it's all direct buried. I'm not an electrician, but I have been explained that such cables needs all the cooling it can get from the soil it's buried in. Telephone cables are also for the most direct buried, thats the way we do it here.
Yes, most of the time big power cables, small power cables, etc. are all pulled into conduit around here. Sometimes very large conduits or multiples. Ease of repair or replacement and extra protection from rocks and rodents are reasons I have seen cited. It doesn't cost a whole lot more to do it this way it seems to me.
I see. Is that in the big cities only or also on the outskirts?
Like Norway, VT gets frozen ground. In the area I live we occasionally have open winter periods. When we don't have snow, frost goes deep into the ground. I've seen the ground frozen 7' deep. I like conduit deep to limit the range of temperatures it is exposed to. 3' deep, conduit temperatures range from 20 F to 60F. Shallow conduit will range from 0 to 80F. PVC shrinks a lot in cold. Glued joints, or in some cases the conduit itself can break from the stress of contraction. I've buried a lot of conduit in 48 years. I take great pride that I've never replaced an underground line I put in. I have replaced numerous ones others installed. There's always somebody looking for a quicker, cheaper, easier way to install underground wiring. Most of these result in cable replacement in the future. With a proper conduit job, new cable could, (should it ever need replacement, but conduit makes it less likely) be replaced easily, even in winter. I reject the heat argument. Properly sized cable will not overheat, conduit, or not. Willie
In the National Electrical Code, there is quite a significant allowance for higher amperage for conductors buried directly in earth over conductors in conduit in earth, but only in the above 2000 volts charts. So there is significantly better heat dissipation for direct bury. (The allowance does not extend to low voltage wires probably because they expect us hillbillies don't know how to use charts or something like that) Still they don't usually direct bury high voltage because the lower cost of installation (using smaller wire) would be offset by higher repairs in the future.
Only service lines from the main to the home are direct buried here, everything else is directionally bored with conduit.
Around here the POCO requires 4" conduit from the transformer to the panel with extra long sweeps and I think a mandrel pull, only then will they pull in wire or maybe you pull the wire, don't remember now. Anything they will have to maintain in the future is required to bombproof. As for ripper laying, well, you can lay HDPE conduit off a coil, sometimes with cable already installed, but the stuff is like a coiled snake to work with because it wants to form back like it was on the reel. So unless you have a lot of stuff to plow it doesn't really make sense. They did a fiber optic conduit project here a few years back that crossed 10 or more counties mostly following county roads, and it was done with a lot of this ripping and HDD'ing so I have seen it done at least that time but most utilities here are overhead instead.
Here, the rules are iron clad, no exceptions, you will be held to the letter of law! Sometimes. I could not slip anything past the power company enforcers. I see so many F Us I believe they look the other way most of the time. What it is that motivates them to look the other way? I speculate. Fact is; if I care about my reputation, and my customer, I install underground I believe will last. Deep keeps it away from extreme temperature swings, retired Joe-Bob with his 10 HP compact diesel backhoe planting posies, and the odd concrete truck. Surrounded in sand protects from rocks. Conduit offers me the luxury of replacing the cable later. Anything less serves only bean counters, not economists. Willie
Thanks for all the replys. I was i Vegas for the Con/expo, much great stuff to see there and no computer time I have watched some youtube videos of ripper laying. I can say so much that this will never work here in Norway. Wherever we try to dig there will be boulders or/and rock 90% of the time. So we excavate a trench and make a 4" sand bed for the cables and then cover with 6" of sand before backfilling. Here is a video I found on youtube of ripper laying direct buried cables. I just don't understand how they can do it this way, the ground is full of sharp stones. That cable is doomed in my opinion. See it here:
Note the OP stating it was a government job, and they opted for direct bury because it was cheaper. We'll see.
Yes I noted that, but anyway no good
I once did electrical work on buildings for a contractor who grew a good business building both overhead, and underground phone lines. In my earliest knowledge they plowed in phone cable up to 200 pair. It was done with an International TD 15 (15 metric tons) crawler with a vibratory plow pulled behind. They would plow until the plow wouldn't move, dig a hole with a backhoe to relieve the obstruction, and continue. I feel the logic was so much money was saved plowing it in, they could afford to do it twice. I also believe the bean counters at the phone company were concerned for project numbers under scrutiny from stockholders. It'd be somebody else's problem to explain replacement costs years too early. This of course was 48 volts DC that it operated at. Little safety concern. In those days, phone line carried only voice, not as much a crisis if it failed. In those days 50 pair was usually buried from town (1000 people) to town. Those pairs carried 1 conversation at a time. The owner died a couple seasons ago. The prime mover of the company sold at auction in the $4,... range. I was licking my wounds for not attending the auction. A functional TD15 for less than $5,000.
I still see a lot of direct bury power in residential subdivisions. The last new residential street we put in over a year ago was direct bury. We installed the conduit for the road crossings but the rest of the primary lines to the transformers were direct buried. Road Crossing in conduit. Bedded the line with 57 6" above and the rest was dirt. Commercial is a different story. This is 2 - 5" conduits from the power co's pull box to a three phase power pad, one is for cable and one is a spare. Bedding the 5" conduits in 57 stone. The way the laws are here is that we can run commercial primary conduit from the power company's pull box to the transformer pad. We can install this portion as it's owned by the power company up to the pad. An electrician has to run the secondary from the pad to the building as this is owned by the building owner. The power company pays for the wire to the pad and the owner pays for the secondary from the pad to the building. I found a little niche of value engineering for the clients I work for in locating the transformer pad as close to the building as possible. Utility Lines Construction Services aka Asplundh installs all the residential primary and secondary underground power in my area. There trucks are outfitted with a knuckleboom crane to lift the wire spools and I've seen them use a backhoe to lift the reels for laying cable in the trench.