Hello all,
Usually, we battle objectionable current within residential, commercial, or industrial facilities and view the water main outside in the street as a completely foriegn system that we don't need to deal with. We keep it in mind when we talk about having objectionable current or harmonics leak into the common street water main and over into our own systems from neighbors but what if we are actually going to work on the water main?
I have a project where a water main needs to come above ground for a street crossing. It is an old metal water main. It has been identified that the water main has stray current people have felt "shocks" from it.
In the electrical industry we know that sometimes the water main reluctantly becomes a "backup neutral" whenever there is an incorrect wiring situation on a premisis or a neutral connection to a facility is severed since the NEC requires that the water line coming into the facility be bonded to the neutral at the service equipment. If the neutral conductor is removed, the only way back to the source is through the water pipe coming to the house and then ultimately to the water main and hitching a ride back to the service transformer via a neighbors neutral line.
Two questions:
1. How do you make the water main safe so pedestrians do not get shocked?
2. When the utility works go to work on water mains, how do they not get zapped when there is often objectional current on the water main?
Usually, we battle objectionable current within residential, commercial, or industrial facilities and view the water main outside in the street as a completely foriegn system that we don't need to deal with. We keep it in mind when we talk about having objectionable current or harmonics leak into the common street water main and over into our own systems from neighbors but what if we are actually going to work on the water main?
I have a project where a water main needs to come above ground for a street crossing. It is an old metal water main. It has been identified that the water main has stray current people have felt "shocks" from it.
In the electrical industry we know that sometimes the water main reluctantly becomes a "backup neutral" whenever there is an incorrect wiring situation on a premisis or a neutral connection to a facility is severed since the NEC requires that the water line coming into the facility be bonded to the neutral at the service equipment. If the neutral conductor is removed, the only way back to the source is through the water pipe coming to the house and then ultimately to the water main and hitching a ride back to the service transformer via a neighbors neutral line.
Two questions:
1. How do you make the water main safe so pedestrians do not get shocked?
2. When the utility works go to work on water mains, how do they not get zapped when there is often objectional current on the water main?