Fused disconnect to protect aerial line ahead of service disconnect

[elec-tech]

I have a 400' aerial pole line that now runs from the Service Point (on a private utility pole, one span in from the utility company pole) and then to the existing building. I want to protect this triplex cable since it runs through large trees and i don't want a short or ground fault caused by a downed tree or broken limb to damage or destroy the aerial feeder. The building has an existing service disconnect typically located immediately inside the outer wall of the building. Section 230.82 (1) allows "current limiting devices" to be installed ahead of the service disconnect. To me a fused disconnect certainly meets the criteria of a current limiting device, but a local "code expert" I discussed this with tells me 230.82(1) is not applicable here. He says that if I want to add the fused disconnect near the street, it must become the new service disconnect. He claims that the first disconnect on the premisies MUST be the service disconnect. If I make the disconnect on the pole the service disconnect, I would need to carry the additional grounding conductor and also run my grounding electrode conductor 400' to the pole mounted disconnect. My grounding electrode will now be 400' from the building, in my view not desireable in case of a lightning strike or a ground fault. To me situations like this are exactly why 230.82(1) was written.What do you think?

 

[Dennis Alwon]

First off I can't believe you are running a cable 400' with no support in between. There must be a tension issue there for sure--- Not sure how to calculate that but this does not sound compliant. Are you using the trees to hold this cable?.

Okay, Now the meter is at the pole 400' away from the house? If so then IMO, no disconnect is needed there and you would only need 3 conductors. If there is a disconnect at the site of the meter then you would need 4 wires but you would not need a grounding electrode conductor just an equipment grounding conductor.

 

[texie]

I have a 400' aerial pole line that now runs from the Service Point (on a private utility pole, one span in from the utility company pole) and then to the existing building. I want to protect this triplex cable since it runs through large trees and i don't want a short or ground fault caused by a downed tree or broken limb to damage or destroy the aerial feeder. The building has an existing service disconnect typically located immediately inside the outer wall of the building. Section 230.82 (1) allows "current limiting devices" to be installed ahead of the service disconnect. To me a fused disconnect certainly meets the criteria of a current limiting device, but a local "code expert" I discussed this with tells me 230.82(1) is not applicable here. He says that if I want to add the fused disconnect near the street, it must become the new service disconnect. He claims that the first disconnect on the premisies MUST be the service disconnect. If I make the disconnect on the pole the service disconnect, I would need to carry the additional grounding conductor and also run my grounding electrode conductor 400' to the pole mounted disconnect. My grounding electrode will now be 400' from the building, in my view not desireable in case of a lightning strike or a ground fault. To me situations like this are exactly why 230.82(1) was written.What do you think?

I think your local guy and Dennis are correct. If you add a disco. at the meter that will be your service disconnect and will then require an EGC to the house. Assuming you own the triplex conductors from the meter to the house (as opposed to the POCO) you could use cable limiters for a little extra protection by spicing them in at the weatherhead at the supply end. Just keep in mind that these are not the same type of protection as a fuse but they have their place. CooperBusman makes them among others.

 

[mgookin]

Consider underground.