Service Conductors and Feeder Conductors in Same Raceway

[jap]

I was looking at the Graphic that Makes it illegal to install Service Conductors in the same raceway as Feeder or Branch Conductors saying that if there was a fault it would bypass the service disconnect and energize one phase of a panel that it was feeding and the circuits connected to that phase.This would have to be a perfect scenario where if there was a fault, the fault would have to be between a Service Conductor and a Feeder Conductor of the same Phase, Otherwise something would blow up or the primary fuses would most likely blow for going phase to phase.Whats the chances of a fault occuring in a Service raceway where the fault would cross only a feeder conductor of the same phase? (Not Likely).One could argue the same point on a Feeder and Branch circuit scenario. Take a 500 mcm feeding a 400amp panel and a #12 Branch circuit out of that same panel. If for some reason the #12 dug into the 500 MCM Miraculously on the same phase, The #12 would be fused at 400 amps and would not be able to be shut off by the 20 amp breaker.Or if it dug into a 500 mcm on a different phase something would blow.Just another arguable fact of where to draw the line on some things.
There are still a ton of up and down services being built.

 

[iwire]

The 'primary fuse' may never blow, it is not there to protect the conductors or the transformer it's only purpose is to protect the grid from being taken out.

Almost anytime you have a conductor fault in a conduit it does get into the other conductors.

It's a good rule and you can not compare unprotected service conductors with feeder conductors. The fault current and duration can be very different.

 

[Mule]

Also the transformer is likeley to be sized large enough for several structures and fused the same. So a fault in the riser can be very violent, thus the extra bonding requirements....So its not a good environment for other premise wiring to share the same raceway....

On the contrary, we have a local rural poco coop that has done this practice for ever and still does it today. They build the meter loops themselves with line and load in the same riser and mount them on a pole free of charge to their customers. The customer just pays for main breaker, which I think is a liability game.