telecomm wiring next to high voltage
telecomm wiring next to high voltage
(OP)
Is it acceptable practice to route telecommunications lines adjacent to high-voltage distribution lines in an underground duct bank?
This particular situation involves a 7200 volt primary electric cable in 4” pvc conduit, serving up to 150 kVA of load. In the same trench, in another 4” pvc conduit, are a number of Cat 6 cables carrying data and phone. The conduits are separated by 4” to 6”, and run next to each other for 500’. Will the high voltage primary cause any interference on the data lines?
This particular situation involves a 7200 volt primary electric cable in 4” pvc conduit, serving up to 150 kVA of load. In the same trench, in another 4” pvc conduit, are a number of Cat 6 cables carrying data and phone. The conduits are separated by 4” to 6”, and run next to each other for 500’. Will the high voltage primary cause any interference on the data lines?






RE: telecomm wiring next to high voltage
Please let me know of any concerns I should be aware of. It just seems that the 60-hz hum would affect computer network wiring.
RE: telecomm wiring next to high voltage
Cat-6 cables have twisted pairs specifically for the purpose of minimizing electromagnetic interference.
Also, Cat-6 runs should be limited to 100 meters between devices. Beyond this distance the signal loss can be great enough to cause equipment malfunction.
If you have the money to spend, fiber would be the way to go as far as eliminating the distance and interference problems - if you don't mind spending a couple thousand for that 500 foot run.
RE: telecomm wiring next to high voltage
More separation is always better. Shielding of both the high voltage and CAT 6 cables will also help. Steel conduit would help as well.
Personally, I would try to get more separation. But it may not cause any problems.
And you won't hear much hum coming from the feeder.
RE: telecomm wiring next to high voltage
Yes eyrp, I agree that fiber would be the best way to go. But there may also be some analog lines for phone, intercom, and radio communication, which was where I was concerned with the 60hz hum.
RE: telecomm wiring next to high voltage
Speaking from experience, in a mixed use (residential and light retail) development project here, the electric, cable tv, and phone cables were all placed in the same trench. Our specifications stated that the communication facilities should be at least 12" above our electric cables but I know from seeing the project during construction that it did not happen. The phone and cable ducts were installed at the bottom of the trench right alongside the high voltage electric. Each utility had its cables inside their own HDPE Duct so no steel conduit was used. This method was used all over the development that had several thousand feet of trench. I spoke with the phone and cable reps this morning onsite and there have been no complains from any of their customers. There are already about 500 customers online over the past 2 years so it seems that everything is working well.
As I quoted dpc above, it can't hurt to use shielded cable and steel conduit for the communication lines. Those methods are proven to work in high interference environments.
RE: telecomm wiring next to high voltage
Good luck.