jamesgang
Member
- Location
- Okmulgee, Ok USA
I have a question concerning a 120/208 3 phase 4 wire service. This question has come about because of the very expensive and time prohibitive nature of running a new service.
The existing service is 208 3 wire 400amp with three 500kcmil that the plans call for 120/208 4 wire. There are two parallel 3" EMT's running a few inches apart over 150' through the bowels of a hospital which have 3 500kcmil in each. One conduit is a spare with cables installed.
We realize we cannot use the spare conduit with the three 500's ( spares) for a neutral due to transformer action and heating of the pipe.
However if we used one conduit for phases A & B and used the included third phase as a neutral then use the second conduit as C phase and used a second conductor in that conduit as a neutral which would be connected at both ends ( paralleled) will it cancel out the objectionable fields in both conduits having a neutral in each pipe? :?
The existing service is 208 3 wire 400amp with three 500kcmil that the plans call for 120/208 4 wire. There are two parallel 3" EMT's running a few inches apart over 150' through the bowels of a hospital which have 3 500kcmil in each. One conduit is a spare with cables installed.
We realize we cannot use the spare conduit with the three 500's ( spares) for a neutral due to transformer action and heating of the pipe.
However if we used one conduit for phases A & B and used the included third phase as a neutral then use the second conduit as C phase and used a second conductor in that conduit as a neutral which would be connected at both ends ( paralleled) will it cancel out the objectionable fields in both conduits having a neutral in each pipe? :?