Can anyone tell me when the current roof clearances for service drops was adopted. As an engineer for the local poco, I have instructed our servicemen not to energize violations. One of the most common violations are the old single wide manufactured homes with mast that are only 10 to 12 inches tall.....impossible to connect without violating clearance requirements.
Roof clearances
- Thread starter magoo66
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charlie
Senior Member
- Location
- Indianapolis
Re: Roof clearances
Your company should have an engineering library with past copies of the NESC (our service drop is not covered by the NEC). The AHJ is responsible for the point of attachment and that is covered by the NEC in 230.24. I think you will have to go back a long ways to find anything less than 18" in the NESC.
Your company should have an engineering library with past copies of the NESC (our service drop is not covered by the NEC). The AHJ is responsible for the point of attachment and that is covered by the NEC in 230.24. I think you will have to go back a long ways to find anything less than 18" in the NESC.
Re: Roof clearances
NEC 230.24 covers the service drop. 230.26 covers the point of attachment. This is an instance of overlapping jurisdiction.
Under some instances NECS allows lower clearances than NEC because NESC *** -umes that utility linemen and engineers have more skill and experience sagging a line correctly than building electricians.
If there is a clearance problem, why don't you install a beside-the-building pole? Quite a few 1 story commercial buildings around here have these. If you run jacketed service entrance cable on a messenger wire from this pole to the meter socket you can get around the clearance problem. I have even seen a residential service ( in Pittsburgh, PA ) in a well to do neighborhood where SEU cable was used as the service drop and ran unbroken from the pole across the street to the meter socket.
Services are not supposed to be attached directly to a manufactured building anyways. SquareD makes an excellent meter main that is great for construction services, mobile home services, and so forth. The catalog number is QC816F200CH which has a 200 amp main breaker 22,000 AIC, 200 amp power takeoff lugs, horn bypass for the socket, and an 8 slot panelboard. If you stick in a QCGK3 generator interlock kit and backfed breaker it is also a listed manual transfer switch.
NEC 230.24 covers the service drop. 230.26 covers the point of attachment. This is an instance of overlapping jurisdiction.
Under some instances NECS allows lower clearances than NEC because NESC *** -umes that utility linemen and engineers have more skill and experience sagging a line correctly than building electricians.
If there is a clearance problem, why don't you install a beside-the-building pole? Quite a few 1 story commercial buildings around here have these. If you run jacketed service entrance cable on a messenger wire from this pole to the meter socket you can get around the clearance problem. I have even seen a residential service ( in Pittsburgh, PA ) in a well to do neighborhood where SEU cable was used as the service drop and ran unbroken from the pole across the street to the meter socket.
Services are not supposed to be attached directly to a manufactured building anyways. SquareD makes an excellent meter main that is great for construction services, mobile home services, and so forth. The catalog number is QC816F200CH which has a 200 amp main breaker 22,000 AIC, 200 amp power takeoff lugs, horn bypass for the socket, and an 8 slot panelboard. If you stick in a QCGK3 generator interlock kit and backfed breaker it is also a listed manual transfer switch.
charlie
Senior Member
- Location
- Indianapolis
Re: Roof clearances
NEC 230.24 covers the service drop. 230.26 covers the point of attachment. This is an instance of overlapping jurisdiction.
This is a common misconception. The NEC covers customer owned and maintained service drops and service laterals. The NESC covers utility owned and maintained service drops and service laterals.
Under some instances NECS allows lower clearances than NEC because NESC . . .
This is also not true. The NEC takes the simple approach of using a distance for ground clearance . . . period. Since most of the NEC work is on a single private property, nothing more is normally required. The NESC uses the lowest point of conductor sag that is determined with the heaviest loading and the hottest day with no wind or the heaviest ice loading at 32?F and no wind. This requires engineering software like SAG 10 from Alcoa to perform these calculations under engineering supervision.
By the way, take a look at 550.10(I).
NEC 230.24 covers the service drop. 230.26 covers the point of attachment. This is an instance of overlapping jurisdiction.
This is a common misconception. The NEC covers customer owned and maintained service drops and service laterals. The NESC covers utility owned and maintained service drops and service laterals.
Under some instances NECS allows lower clearances than NEC because NESC . . .
This is also not true. The NEC takes the simple approach of using a distance for ground clearance . . . period. Since most of the NEC work is on a single private property, nothing more is normally required. The NESC uses the lowest point of conductor sag that is determined with the heaviest loading and the hottest day with no wind or the heaviest ice loading at 32?F and no wind. This requires engineering software like SAG 10 from Alcoa to perform these calculations under engineering supervision.
By the way, take a look at 550.10(I).
Re: Roof clearances
Thanks for the input guys. This has become an issue since a recent PUC inspection flagged several (possibly hundreds) of similar violations. Utility owned pole with a customer owned double masted metered main attached. The four wire overhead FEEDER is what the PUC inspectors were writing up. I would like to say that my utilitys liability ends at the cash resister, however, we have adopted the practice of installing these feeders (probably to keep unqualified workers off the poles).
Thanks for the input guys. This has become an issue since a recent PUC inspection flagged several (possibly hundreds) of similar violations. Utility owned pole with a customer owned double masted metered main attached. The four wire overhead FEEDER is what the PUC inspectors were writing up. I would like to say that my utilitys liability ends at the cash resister, however, we have adopted the practice of installing these feeders (probably to keep unqualified workers off the poles).
charlie
Senior Member
- Location
- Indianapolis
Re: Roof clearances
WOW! That is why we never do anything major beyond the service point. In the situation you describe, we require the customer to provide their own pole, service entrance, service equipment, and feeders. The work beyond the service point is to be done in accordance with the NEC and we do not have many people who know the NEC (I am an exception).
I recommend that your company set up a contract with an electrical contractor to fix the violations that were done years ago.
WOW! That is why we never do anything major beyond the service point. In the situation you describe, we require the customer to provide their own pole, service entrance, service equipment, and feeders. The work beyond the service point is to be done in accordance with the NEC and we do not have many people who know the NEC (I am an exception).
I recommend that your company set up a contract with an electrical contractor to fix the violations that were done years ago.
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