sub panel to pole barn / workshop

[luv2eat]

Hi, I am a new member and have a question about wiring up a subpanel to my workshop. There is an underground feeder to the workshop which is 3-wire 2-2-4 AL all wires insulated. The feeder was put in about 14 or more years ago and i think at that time a 4 wire feeder was not required.

I want to replace the breaker box and redo some of the circuits in the workshop.

It is my understanding that use of the 3-wire feeder is ok since it is an older installation (i.e. grandfathered in). I will be putting in a new ground rod but I am not sure whether the neutral should be connected to ground in the box in my workshop or whether it should be kept separate. I understand that if I had a 4-wire feeder they should be kept separate but I am not sure what should be done for the 3-wire feeder.

What was the code for the earlier installation and how should the breaker box be wired?

Thanks in advance for your help.

 

[nine4gmc]

It's my understanding that you will need two ground rods at the pole building but please do not take that as actual knowledge, let someone with experience chime in. Mine has a 3 wire running to it also and did not have ground rods but I will be adding them when I get back to wiring the additional outlets.

 

[wyliesdiesels]

Since your feed is 3-wire then neutral is bonded to the panel enclosure and ground bar.

Is there any metalic conduit or piping between the buildings?

 

[miner]

The point of not bonding the ground to neutral at a subpanel is so that you don't set up an alternate path for the neutral current. Meaning, if they were bonded at the subpanel then the ground wire would be carrying current back to the main panel when it shouldn't be carrying any current at all unless there is a fault.

I am assuming you currently have 2 hots at 240V (the 2 awg) and one neutral conductor (4 awg). Hence, no grounding conductor run between main and subpanels. Is that right? In that case you DO want to have the neutral and ground bonded at the subpanel. I.e., you treat the subpanel just like a main panel.

Here is a link to another forum where this is discussed in some detail (starts about half way down the page)

http://www.mikeholt.com/forum/Forum1/HTML/003455.html

 

[luv2eat]

Yes, it is 240 volt, with the 2 larger wires hot plus an insulated neutral and there is no conduit (direct bury) except for the risers into the building.

So for my situation I will be driving a new ground rod and bonding the ground to the neutral. I appreciate your help on this and that link provided was also helpful.

Thanks for your help