Do we need armoured cable for CCTV?

[missmimi 0]

Hi everyone,

 

We have to lay cctv cables across the street with part of the cable to be buried underground. I was told that we need to use armoured cable. Do we really need armoured cable? Usually we will use RG59 and powercable in PVC conduit piping burried underground. Is this combination able to withstand being buried underground?

Why is there a need for armoured cable?

Please help...

Thanks!

[Guest]

Hi everyone,

 

We have to lay cctv cables across the street with part of the cable to be buried underground. I was told that we need to use armoured cable. Do we really need armoured cable? Usually we will use RG59 and powercable in PVC conduit piping burried underground. Is this combination able to withstand being buried underground?

Why is there a need for armoured cable?

Please help...

Thanks!

 

Standard cable (coax or CAT5) should not be installed underground as moisture will comprimise the sheath over time.

 

Ducts do not prevent water getting to the cable.

 

There are specific types of over sheathing that are designed for underground use which does not need to be armoured.

 

Armoured should be used where there is a possibility of physical damage and this type of cable normally has waterproof oversheath (check this).

 

You will still need to also do your cable design in relation to length depending on the circuits to be transmitted in the normal way.

 

Hope this helps

 

Ilkie

[jeromephone 6]

I agree with ilk even in conduit you will get moisture and regular cable will soon fail. Direct bury is what we use as it will hold up even if the conduit gets water in it.

[tweak'e 0]

you can get flooded underground cable easy enough. its just silicon filled to stop water traveling through it. however i would always put it in conduit of some kind. direct burying of cables, especially under roads/driveways, the road tends to compact down and the cables get crushed or broken.

[rory 0]

Ive had some regular RG59 in standard PVC under a driveway now for years and its still good .. but a street I imagine is a whole different story. I guess if I had easy access to direct bury Copper Coax Cable then I might had done it different but .. gotta work with what you have sometimes

[Soundy 1]

We've got installations in gas stations running RG59, station wire, 18/2, 18/4, and/or Cat5e, all basic CMR/FT-4 rated for a variety of camera and intercom purposes, all through underground EMT, and have never to my knowledge had a problem with any of it (other than a Bobcat operator shearing the intercom lines during a site renovation, requiring a complete re-wiring of those runs). This is all by customer spec, the customers being two of Canada's major oil companies, so if that spec is good enough for their engineers...

 

As with Rory's experience though, those are basically "driveway" installations, not under streets... then again, they're all in EMT, which is FAR from sealed along the length, whereas properly assembled and glued PVC should be pretty water-tight along its length.

[WRS_Mark 0]

I worked for years in residential excavating where we would trench the power, phone line and coax to houses. Everything from the property line to the house was buried under 8"-12" of sand, warning tape placed over top and then back filled. The coax being used was the cheapest crap out there and I don't recall ever seeing an issue with it unless it was damaged during installation.

 

For roadways, we would simply run the same cable through conduit. That had more to do with our winters here where you could see 8'-10' of frost pounded under the road and the coinciding heaving.

[hardwired 0]

I always try to run direct burial type cable, in PVC conduit. Here, at least, even properly installed conduit always seems to have some moisture in it. If you have a conduit in place, you have more options for later repairs and possible upgrades/additions (fiber, etc.), compared to having to dig again later..

 

Go a little larger, and throw in a extra pull string, too, if you want to be really nice. (how come it seems like no one ever does that for us, though?)

 

Some of you have probably had the fun of trying to break out the poured in sealant in gas station conduit fittings to add cables, haven't you?

[Soundy 1]

Some of you have probably had the fun of trying to break out the poured in sealant in gas station conduit fittings to add cables, haven't you?

 

I worked with one guy who almost broke his nose trying to get that stuff out... had the coax wrapped around a hammer handle pulling on it trying to get the last chunk out, when the wire snapped and the hammer whacked him in the face. Bahahaha!

[jeromephone 6]

I should have said we run the direct bury in conduit. Larger conduit is always better and leaving a string makes adds much easier. In MI we also have to deal with frost as in a roadway it may be 4 feet in the ground. We were on a job where someone left a coax in the bottem of a manhole it rained and the standard coax wicked the water right up about 6 feet of cable in a couple of days. I can't think the cost difference in the cable prices is worth taking a chance.

[bpzle 0]

We have 500 plus sites with conduit running all over parking lots for the past 15 plus years. All we use is standard cheap 22/4, cheap rg6, cheap UTP, and cheap 18/2 running to all types of equipment. I might add the parking lots see very heavy traffic. Everyday a min of 1500 cars, a few dozen semis, and lots of delivery trucks. No problems at all. Just like high voltage... if it's in properly installed conduit and the cable wasn't damaged during install it's fine.

 

Terminations and splices, however are a different story. Obviously you need to enclose and protect these with more than just conduit.

 

Case and point:

I had the pleasure of troubleshooting some strange problems on one site. I eventually found where some donkey ran out of 25 pair, spliced more on and left them in the conduit, unprotected and wrapped in a ton of electrical tape. It took 4 years before there were problems, but it eventually surfaced.