subfeed 4 wires

[domnic]

why must we run 4 wires to a subfeed ??????????????????????????????????????????????????????????????????????????

 

[Little Bill]

Because 3 is not enough?

 

[Dennis Alwon]

Because if you only ran 3 wires the neutral would carry current as well as the equipment grounding conductor.

 

[LarryFine]

why must we run 4 wires to a subfeed ?

As opposed to what?

 

[roger]

Might even need five

 

[Tulsa Electrician]

why must we run 4 wires to a subfeed ??????????????????????????????????????????????????????????????????????????

You do not need to depending on what your doing.
An example would be if you used EMT for a single phase run. You could the EMT as the EGC.
If you sub feed was 110 volt only it could be a three wire cable.
Or if was a 60 /120 volt feeder.

It is common place now for a wire type EGC even in raceway that qualifies as as an EGC.

Devine your question a bit and we can provide a better answer.

 

[domnic]

Because if you only ran 3 wires the neutral would carry current as well as the equipment grounding conductor.

in your service the neutral the carries the egc wats the difference. ( is it safer to run 4 wires )

 

[LarryFine]

The difference is that we don't know or care whether voltage is dropped along the neutral before it gets to us (although we now know that POCO neutral issues can cause us some headaches).

At our service, our reference point of zero volts to earth is re-established. On our premises we do care about neutral voltage drop, and we don't want our bonding to be presented with voltage.

The sub-feed EGC is the reference zero volts to earth. Other than OCP, we treat a neutral as an ungrounded conductor. A compromised one-wire EGC/neutral can cause voltage on surfaces expected to have none.

 

[Tulsa Electrician]

Neutral-to-Ground Connections

See if this helps.