Cutting neutral and 220ing shared circuit

[HAHA THE MOOSE]

Hi I was hoping someone could explain to me how when you are sharing a neutral on a branch circuit and you cut that neutral without deenergizing the shared circuit why are you susseptable to backfeeding on the other ungrounded conducter. I understand that it happens I just don't understand the technical reason why.

 

[infinity]

It's because the two loads are now in series and each load will see a different voltage drop across it based on it's resistance. The current will be the same through both loads. Two equal loads will share the total voltage equally. For a 208 volt system two identical loads will have 104 volts across them. For a 240 volt system the two loads will have 120 volts across them.

 

[chris kennedy]

Hi I was hoping someone could explain to me how when you are sharing a neutral on a branch circuit and you cut that neutral without deenergizing the shared circuit why are you susseptable to backfeeding on the other ungrounded conducter. I understand that it happens I just don't understand the technical reason why.

Power is going into the shared circuit. It will travel through a load and look for a return path to the source. Hence, energized grounded conductor.

 

[nakulak]

draw it out on a piece of paper

plug on left is fed from left with a phase

in middle is juction box with neutrals

plug on right is fed from right with b phase

cut neutral going to panel, and you have a phase on left plug, former neutrals connecting the two plugs are now just a jumper, and b phase on right, so now you have the two plugs fed with 220. make sense ?

 

[HAHA THE MOOSE]

Man you guys are great. Thanks for the info.

 

[Power Tech]

you will also have a deadly load to ground on the "open Neutral".

 

[480sparky]

Click here.