Catenary wire- How to Support for Cat5 or RG59 cable

[Numb-nuts 1]

I just did a job this week, the first time I actually installed galvanized wire-rope to carry cables from one building to another and installed the wire rope myself. In the past (2 times) I actually paid a contractor to install these catenary wires but the guy I use has had an accident and can't do them anymore. Fortunately, the distance was just short of 7 meters. I may use 5mm galvanized wire rope since the distance of the next one has doubled and I used 4mm rope on the first one. The wire rope maker was very helpful in advising me.

 

I knew that tensioning the wire rope required a turnbuckle, and that a means of securing the rope at both ends was required. At both ends, I started with a galvanized staple, one was secured to a brick wall with 4 x 2.5 inch no7 screws. The other end was secured to a lamp-post on the site (privately owned) using sticks all adhesive and a 13mm stainless steel band kit. Like a 3m jubilee clip with several buckles that you make your own size band clip. Then I attached the turnbuckle to the staple using a shackle and a few spacing washers to keep the turnbuckle at the center of the shackle. (Actually, most of the washers in the packet ended up on the floor at the base of the ladder.....oh well). I measured the distance to the other shackle shackle ad deducted half the adjustment of the turnbuckle in this case 50mm. You specify length of wore ropes from bearing point to bearing point. I didn't want to buy a swageing tool (crimping) since they are about £60.00 or $100US and I would rarely have need of it. The wire rope arrived and it was tough getting it to tension up enough to hook it onto the turnbuckle, but once I had done this, it was simply a matter of holding the wire rope loop in my right hand and taking a slot type screwdriver through the turnbuckle rotation until the wire is taught enough to support a couple of wires without sagging. I have the first cable up and it's solid as a rock, but it does slope a little. When I measure the height of the staple on the wall, I hadn't noticed that the ground level was slightly higher than that at the base of the post. Fortunately, the post was secured with a stainless steel band which can be undone and slid up the post a little until level. Just looks a bit more professional.

 

The first one I did took me about 4 hours, the second one has only taken 30 minutes but I have yet to install the wire rope as I haven't ordered it yet. I have yet to measure the distance which is more than twice the length of the first one. I have realized I will need to use two turnbuckles or I stand no chance at all of pulling the wire onto the hooks at each end. I only realized this after installing the first wire rope. I will post photos of the various components and setup I used next week as I have been too busy to photograph the work yet.

 

Below is a picture of the stainless steel banding kit I bought and used at the lamp posts. These kits are readily available on ebay but I bought mine fromAbbey Clamps UK.

 

I am welding up special mounting brackets this weekend which I designed myself. They consist of a galvanized steel plate and pieces of 1 inch square box section welded along the long dimension of the plate. The gap between the box sections will be at least 4 inches (100mm) and this is where the junction box and the cameras will mount. There are two cut out slots in the box section to allow me to pass the steel banding through before it goes around the post and is then tensioned up. I will use two bands to hold the plate to the post which is a strange triangular shape and made from reinforced concrete. I was advised NOT to drill into the lamp post as there are live electric cables inside, (high Voltage).

 

JUST A POINT TO MENTION ABOUT HEALTH AND SAFETY, ALWAYS WEAR EYE PROTECTION AND GLOVES WHEN HANDLING WIRE ROPE

 

Edited February 24, 2014 by Guest

[ilk 0]

A couple of points.

 

We buy our wire in 100m reels, cut to length ourselves and teminate with a thimble and two 4mm U bolts at each end.

 

When you install allow for the expansion/contraction effect caused by variations in temperature. (we have seen fixing failing as the catenary wire was pulled too tight.

 

Another issue will be the use of solid core cables on catenary. The movement of the suspended cable due to wind will cause solid core cable to break so either use purpose designed cable or cables with multiple strands (ie URM70 coax or CAT5E designed for patch leads).

 

Of course the overall sheath should be designed for external use with UV resistance.

 

Ilkie

[Numb-nuts 1]

A couple of points.

 

We buy our wire in 100m reels, cut to length ourselves and teminate with a thimble and two 4mm U bolts at each end.

 

When you install allow for the expansion/contraction effect caused by variations in temperature. (we have seen fixing failing as the catenary wire was pulled too tight.

 

Another issue will be the use of solid core cables on catenary. The movement of the suspended cable due to wind will cause solid core cable to break so either use purpose designed cable or cables with multiple strands (ie URM70 coax or CAT5E designed for patch leads).

 

Of course the overall sheath should be designed for external use with UV resistance.

 

Ilkie

 

Thanks for that Ilkie it's very helpful. If I do get a few more like this I will indeed buy the wire rope in bulk (100m) and my own swaging tool (like a bolt cropper) and wire cutter. I was NOT keen on the clamps you mentioned but was aware of those, they just seemed too much trouble and a little untidy compared to aluminium (aluminum) ferrules. I was going to order stainless wire but the cable maker advised that I should use galvanized. I thought there might be an issue with the cable moving so I have placed a junction box at both ends (on wall and special mounting plate) and joined the cable with jelly splices remembering to keep the twist as much.

as possible.

 

I fully take your point about using stranded conductor cable as it stands more chance where wind moves the cable.

Solid cable only has to suffer a single conductor fracture and BAM you've lost your signal or suffer a voltage drop.

I have never seen outdoor patch cable but I haven't been looking for it before. I'm certain somebody must make it.

 

as for allowing for temp change and expansion-contraction movement, I installed the wire in really cold weather and will release some tension after loading the cable onto it. Thanks for mentioning that. You obviously have a significant number of this type of job under your bel whereas I have only had a couple, but I think having done a couple I will be significantly more confident about doing them myself.

 

Hand swaging tool and cutters and aluminium (aluminum) (wire rope ferrules) below.

 

[Numb-nuts 1]

Here are some images of the resulting work.

Before any smart-alec comments on the cables, yes I know they are way too short, I made a miscalculation and have now replaced them leaving way more cable to form a drip

 

 

[ssnapier 0]

This is cool, I generally prefer to use cable clamps like this:

 

 

The only thing about these is that you need to put tension on the cable with a come-along, so it is not for everyone.

[Numb-nuts 1]

I've not seen those before. I am thinking that installing a galvanized wire rope, to support external grade (or direct burial cable)

is sufficient for my purpose. Of course start to use more than two cables across the wire rope and it starts to look a little messy and untidy. In such a case I think I'd run a single cat5 to carry 4 signals and use a local electric spur to provide mains power and then transform to either 24VAC or 12VDC locally. I wouldn't feel comfortable carrying mains power over a wire rope, I think there may be too many dangers to risk it. Yes I know power companies do it all the time but they have years of technical expertise in such things I am just a self taught technician.

 

The cable you show in your pics, does it have a support wire inside to protect the conductors from stretching?

It would certainly be a convenient solution if the conductors are UTP.

Thanks for your input.