Greetings,
In a discussion with two other electrical contractors, I was told that (on two separate occasions from two separate engineers) the engineers calculated a service entrance utilizing six disconnects and sizing the service entrance conductors from the 90?C column. When questioned on this practice the engineers cited that because of the diversification of six throws of the hand, they could utilize the 90?C column for their service entrance cable sizing. They both were unable to provide additional details regarding either installation. They both said they were baffled but just went along with the engineers drawings.
I was asked if I had ever heard of this. I had to respond that I was not aware of any instance where the 90?C column could be used for anything other than deration of conductors. Service equipment terminations are limited to 75?C under 110.14(C). I do not see how six disconnects affect this.
Has anybody ever ran into anything like this?
Thanks in advance
mweaver
In a discussion with two other electrical contractors, I was told that (on two separate occasions from two separate engineers) the engineers calculated a service entrance utilizing six disconnects and sizing the service entrance conductors from the 90?C column. When questioned on this practice the engineers cited that because of the diversification of six throws of the hand, they could utilize the 90?C column for their service entrance cable sizing. They both were unable to provide additional details regarding either installation. They both said they were baffled but just went along with the engineers drawings.
I was asked if I had ever heard of this. I had to respond that I was not aware of any instance where the 90?C column could be used for anything other than deration of conductors. Service equipment terminations are limited to 75?C under 110.14(C). I do not see how six disconnects affect this.
Has anybody ever ran into anything like this?
Thanks in advance
mweaver