4 wire conductor or 3 wire conductor

[Bigfork G]

Do i have to use 4 wire conductor OR can i use 3 wire from my meter/ main disconnect to my detached garage? The house and garage are not connected in any way. All the service is under ground.

The reason im asking I called to get prices on wire from two supply houses and got two different answers.

 

[theoldwizard1]

First, check if your power company and local building authority allow you to come directly off of the meter / main disconnect for a second structure. Many require you to go to a main panel and wire it as a "branch" circuit with its own breaker (which is what I would do). Wiring it this way would require 3 wires plus a ground, so 4 wires, although the ground does not have to be insulated.

 

[Bigfork G]

First, check if your power company and local building authority allow you to come directly off of the meter / main disconnect for a second structure. Many require you to go to a main panel and wire it as a "branch" circuit with its own breaker (which is what I would do). Wiring it this way would require 3 wires plus a ground, so 4 wires, although the ground does not have to be insulated.

yes i can, and yes the disconnect has spaces for branch breaker circuits.

 

[Bigfork G]

so 3 wires to the garage with the garage grounded with rods are not sufficient? would the neutral and ground be bonded at the disconnect?

 

[Charles (in GA)]

Code requires that the only place the neutral and the ground be bonded together is at the main disconnect, after that they are to be separated. In your garage subpanel you need a insulated and isolated neutral (not bonded to the shell of the panelboard) and a separate ground bar, bonded to the panelboard shell and connected to the ground wire from the main.

Last code cycle that three wire was allowed was about 1996 or possibly earlier.

 

[sublimate]

You can use 3 wires if you only want 120 or 240 volt power.
But if you want 120 and 240 then you need 4 wires.

 

[dogdog]

maybe a side question.... if there is a metal conduit all the way from Main to sub panel is that consider the 4th grounding wire?

 

[Zachgregg]

maybe a side question.... if there is a metal conduit all the way from Main to sub panel is that consider the 4th grounding wire?

Now I work mainly commercial and industrial so take this with a grain of salt, but yes you can, but you need grounding bushings on both ends of conduit. Than, from the bushing, on both sides of course, you need to bring a wire up to the ground bar. IMO this would be more of a hassle, unless its an extremely long distance.

 

[alfredeneuman]

but you need grounding bushings on both ends of conduit.

Like commercial and industrial, you're only required to have ground bushings on a subfeed if the panel or box has concentric knockouts.

The rules for circuits over 250V to ground are different and don't apply here.

 

[Aceman]

Run 4 wires.

 

[wyliesdiesels]

OP- any feed off a disconnect requires 4-wires...

 

[Zachgregg]

Like commercial and industrial, you're only required to have ground bushings on a subfeed if the panel or box has concentric knockouts.

The rules for circuits over 250V to ground are different and don't apply here.

Learn something every day.