I'm pricing out a job running a 200 pair tie cable within the confines of a power generating plant. Almost all of it (400) feet will be run within existing cable trays indoors. The last 40 feet will be run in a PVC coated 4" rigid steel conduit underground to a hand hole.
I'm planning on running ALVYN cable for this. I need opinions on the following:
1. The conduit is dry and is encased in concrete, so I don't think water will be an issue. It has been there for 15 years and is dry as a bone. Do you think it will be OK to run the ALVYN cable for this short length rather than making a transition splice to ALPETH? Note that there really isn't anywhere that a transitional splice can be made.
2. The cable will be spliced in the hand hole to branch out, so there won't be any terminations. At the switch room end, I'm debating using protection since the building is 100% steel and grounded beyond belief. Not even the incoming telco cable is protected. I'm thinking that just a good job of sheath bonding at each end will suffice.
Any second opinions?
I think your decision is really a splice as a failure point vs water possibly entering the conduit. If it's as dry as you say I think you will be OK. I think the possibility of a splice causing a problem is much more than water in the conduit.
As for grounding, I think you will be OK too. Not much is outdoors, is it?
-Hal
Ed,
It's been a very long time since I've done this and this is just memory work. We never bonded when putting phones inside a power plant or sub stations, our sheath was kept separate from the power company grounds. So I see no problem with the way your doing it.
Guys:
I forgot to mention: What I refer to as a hand hole is more like a man hole. It is about six feet deep from the ground surface. My plan is to terminate the new cable in a bolted aluminum splice case where it will re-feed an existing 100 pair ALPETH cable. I also plan to put a 25 pair pole-mount terminal on the side wall to feed several 5-pair drops going out to multiple buildings. The remaining 75 pairs will be dead-ended for future use.
The station ends of the existing cables already have standard protection (Keptel network interfaces). I'm not really crazy about having all of these cable sheaths not bonded, but it's not every day that I work with power plants.
The bonding is a tough one. I would think about only bonding one end.
-Hal
You bond the sheath to each other and telco ground, just not to the power company ground. I'm sure that's the way it was done Ed, but again going on memory here.
I agree with Bill and Hal, the splice is not an issue...the power plant is. It has been almost thirty years since I spliced in an isolator for a power plant when I worked for a telco. We did protect the cable at the plant end but broke the bond and all copper connections with an isolator cabinet at the property line. Yes, "hand holes" at a power plant are really "manholes" to us. Their "manholes" are almost apartments! Huge. All cables within the facility were bonded, grounded, and protected. The switch was protected via gas protectors on the frame at the MDF.
Your choice of cable should be "Okay". We used a lot of "D" screen cable at the power plant to allow for signal, data, and voice noise shielding.
PANI (Producers, Absorbers, Neutrals, Inductors) as Sprint (now Embarq) uses isolates cable sheaths from main grounds in any digital central office. This prevents multiple ground paths. Bonding the sheaths at the manhole feed location should be okay as long as there is NO bond/connection to the telco feeder bond.
As far as termination protection in the MDF, I do believe I would follow the existing situation although a gas protection to isolated ground would be a good noise drain.
My two cents.
I've never done telephone work in a power plant, but what I'm reading here sounds good.
Sam
When working near or around sub-stations (never working inside a power plant) we floated our bonds to keep them separate from the power bonds.
Jeff