For electrical work on an LV single phase distribution circuit is it OK isolate the live phase?

For electrical work on an LV single phase distribution circuit is it OK to only isolate the live phase of the circuit & why

2 Answers

  • 8 years ago
    Favorite Answer

    Yes, actually you are supposed to. In fact, electrical codes in North America actually go to great lengths to keep people from isolating the neutral conductor.

    You only have to break a circuit in one place to deactivate it, but where you break the circuit matters from a safety perspective. Everything after the break is de-energized (no voltage, no current) but everything before the break is still energized (voltage but no current). Were you to touch the energized side, you'd complete the circuit to ground and current will start flowing through you (you get shocked).

    So logically, the closer to the source you break a circuit, the safer that circuit is to work on because there's less chance of finding something that's still energized. In your house, that means the breaker panel.

    That is why appliances with power switches have two different sizes of prongs on their plugs. It prevents you from reversing the polarity. You want the switch to be on the upstream side of the load so that when you turn it off, everything is de-energized. If the switch accidentally ended up on the downstream side of the load, you could still shut off the power, but most of the electrical parts would still be energized. It would be easy to think you could start touching parts because nothing is on, but you'd quickly wonder why you just got zapped when everything is off.

    That is also why NEC and CEC prohibit placing a switch on the neutral wire, all switches must be upstream of the load on the hot wire. They also place special restrictions on how you can splice neutral wires together so that a future maintenance worker can't accidentally disconnect the it.

    Hope that answers your question

    Source(s): B.Sc. Electrical Engineering
  • Anonymous
    4 years ago

    the single section format will contain 4 wires, 2 warm wires, a independent line, and an earth floor. One warm line to independent is 110Vac RMS. One warm line to the different warm line is 220Vac RMS. the prevalent shops of a well known room are related with the aid of 3 wires, a line, independent, and floor(110V home equipment). the nice and comfortable water heater, dryer, and oven will use all 4 wires(220V home equipment). the three section format will contain 5 wires, 3 warm strains (seen the 0 degree section, a hundred and twenty degree section, and the 240 degree section), a independent line, and an earth floor. There some opportunities for a manner the three section might properly be configured, yet in terms of a format the place the home is to be presented 3 section, all you're able to do is have 5 conductors feeding each and every room. (The cord length relies upon upon how plenty modern you intend to furnish each and every room with, and this will additionally replicate the size of the needed breaker.)

Still have questions? Get your answers by asking now.