ECN Forum Forums Code Related Discussion NEC & other Code issues International Technology

old Appy,

I've been a stump sitter, jumped sometimes when younger, but mostly sit now.

(I don't know the terms either, and I live here!)

Care to help us out guys?

Bill

Appy;
this "ring main" implies that the circuit makes a loop back to, and is connected to it's original feed source.

not a bad idea if there is an underground break, or your wiring a very solid structure.

Try correlating those terms with LINEMAN and WIREMAN

Glenn

Glenn is correct. The name "stumpjumper" is in reference to lineman who climb wooden poles. Lineman would often refer to their selves as stumpjumpers, if an outsider used this term it would usually result in a fist fight.
I don't know the exact origin of "narrowback", my guess is it was in retaliation for inside wireman calling lineman stumpjumpers. The reference was probably to imply inside wireman did not have the physical attributes of the lineman.
This was usually all in fun, and not taken serious.
It does illustrate a separation of lineman and wireman, in the electrical trade.
This separation also created a different viewpoint for the same thing.
Lineman connecting distribution systems, refer to the grounding electrode conductor, neutral, equipment ground, and bonding jumper, as a (MGN) multi-ground neutral system.
Wireman, and the NEC, refer to the various conductors as individual systems. There is a change in definition at the secondary supply of the distribution transformer.
The completed product is the same, only the names change. I personally feel this has created a lot of confusion in understanding the technological reason for grounding, bonding, and providing low impedance path for fault current.

The term "ring main" is as described. The US term is radial, or loop feeder system.
This is a common application for medium voltage distribution systems. Two breakers, of equal size, supply each end of continuous conductors. This permits isolation switches for disabling portions of the system, and continuity of service is maintained for remainder of loads.
Both feeder breakers must be opened to shut down entire system.
This system also provides two devices to see high current inrush, on start up, instead of one.

Glenn, Bennie,

Thanks for clearing that up!
We should put those terms in our 'slang' thread that's somewhere around here.

Bill