Aerial Data Installation

[bwwarden]

I am in the process of having a 6 pair fiber cable installed at my facility. I was told by the Comunication Company's Engineer that the maximum span distance from the service pole to my structure is 120 ft. He also stated that the wall constructed of 8" concrete block with brick veener was not adequate enough to attach an aerial service. I have searched my NEC (Article 800)code book and have found no evidence that these statements are true. Is there another organization that governs utility construction criteria?

Thank You,
Bryan

 

[charlie]

Re: Aerial Data Installation

The NEC is short on any kind of specifications for transverse loading for cable or maximum heavy loading for cable dead ends. I am sure he is using the NESC for his specifications or software that is based on the NESC.

Since the communications company is furnishing the service, you will need to comply with their specifications in order to get the cable. They may be on the conservative side but it is their rules.

 

[bwwarden]

Re: Aerial Data Installation

Thank you for your help... NESC? I don't have access to NESC Standards. Even if I did seems that I have little choice on this aerial situation. I currently have all underground utillities and don't want to place service poles leading up to the faciliy. Direct burrial will be my only option. I was trying to avoid the cost!

 

[charlie]

Re: Aerial Data Installation

There is virtually no limit to the length of the service drop if the anchor is strong enough on the building and there is room for a down guy and anchor at the pole. If the cable is hitting the building under full tension, expect about 4,000 Lbs that the building wall has to be designed to hold.

A down guy is the guy wire from the point on the pole where the dead end occurs to an anchor. Normally, there is a need for a 1:1 lead (the lead is the distance from the pole at the ground line to the anchor). On top of all this, if the pole is not tall enough for the service drop to be installed and the ground clearance to be maintained, you would be required to pay for the pole replacement. I am guessing that the service pole is because of ground clearance.

 

[bwwarden]

Re: Aerial Data Installation

Actually the service poll is in place currently to support existing conduit for an underground service (Telephone). I assume that 19 ft of clearance is standard and the anchor point would be around 35ft. I was not expecting 4,000 lb load. I had assumed even with ice loading at 220 ft this cable would only produce 1400lb load. But I take your work on it. My wall was not designed to support such a heavy deflectice load (4000 lbs). This is a little out of my field... I am a PLC programmer / controls guy. So thanks for taking the time to help out.
I suppose that any utility provider could be considered an AHJ under NEC code can enforce their own design criteria.

Thanks,
Bryan

 

[charlie]

Re: Aerial Data Installation

No, we are not considered to be an AHJ. However, we have set up various requirements for service. For instance, we require the point of contact for a service drop to be a minimum of 13.5 ft in order to meet the NESC's 12.5 Ft of clearance for an open wire service drop across a back yard (the NEC is 10 Ft minimum). For a triplex service drop, it is 12 Ft and both dimensions may be reduced 2 Ft if the construction on the building will not permit the higher distance. Additionally, 22 Ft is the maximum height for a service drop. Why? The ladders we carry will not reach any higher.

Most of the rules we have are to correct a problem we have had in the past and are published. The communications companies have not been around long enough to publish their requirements. Since they do not have metering layouts, they may never publish their requirements.

 

[mc5w]

Re: Aerial Data Installation

Some 1 story commercial buildings around here have a beside-the-building pole that functions as a type of service mast. These are usually 5 inch schedule 40 steel pipe.

You mentioned that your telephone service hits a pole and then runs underground. Why not run some more PVC raceway out to it and run your fiber optic cable in it? You might want to consider 2 conduits especially if the existing conduit is steel underground and likely to be rusted out.