IROB required between buildings

[Snowmonkey]

I have been asked to install a 25 pair cable in plastic conduit underground from the middle of one building to another building 700 feet away. Is the irob required? I assume the irob is fuse protection on the copper pairs.
Also the main building where the partner system is located will have 20 sets and the far building will have 8 sets is there any problem with this setup?

 

[franke]

Should work fine with some caveats. I would use a shielded, gel filled 25 pair cable. Also, the NEC requires that you have a primary protection device at each end of the 25 pair (in addition to your IROB's, which are considered 'secondary' protection devices. Make sure you ground each end of the 25 pair.

Depending on your location and where the plastic pipe is going to be located you will want to make sure that it is buried deep enough to avoid damage, i.e. below the frost line, water saturation (from heavy rains), etc. Generally, 2-3 feet below ground level is sufficient. If your going under a driveway or parking lot, you'll also want it deep enough so it doesn't get cracked or crushed by the traffic on top.

You may also want to add one or more pedistal/pullboxs to ease the installation and if necessary, repair.

Finally, make sure your PVC is sufficiantly large enough to handle the cable plus puller.

franke

 

[telprog]

I would use outside burial cable, and yes you should put entrance protectors on both sides.

A trusted source for years.

http://www.tel-programmer.com

 

[jlshelton]

Partner ACS recommends wiring runs of no more than 1000 feet for system telephones; with the buildings 700 feet apart, plus wiring inside each building, you will be close to the limit on loop length. If you can choose the 25-pair cable, select one with heavier wire gauge - i.e. avoid 26ga wire for this installation.

If you do use shielded cable, soon after installation, hook up a clamp-on ammeter around the ground wire at one end and see how much current is flowing between the two buildings. You can also do some other tests - you want to avoid a situation where you are creating a new ground loop that introduces a lot of hum or worse.

 

[toolman18]

Don't forget about one call, you should alway's have utilities located before you dig anywhere.