On 8/4/2012 1:36 PM, dpb wrote:
On 8/4/2012 11:16 AM, HerHusband wrote:
I dug a trench from the garage to a toolshed, and put about 30 feet of
12-2 UF cable underground to the shed. Before filling the trench, I
decided that maybe it would be best to put two of these cables in so I
have two circuits in there, mainly because it gets so hot in there that
I might put in a small air conditioner.
Both cables are on a separate breaker at the source (garage).

You have four wires total, right?

What I would do to make this legal:

1. Install a double pole breaker in the garage, so your load is divided
between both phases of the 240V supply.

2. Assign two wires as the hots (probably the black from each cable), one
as a neutral (one of the whites), and one for the ground. It might take
some work with a multimeter to determine which white wire is assigned as
the ground on the other end (connect a white and a hot on one end, and
check for continuity between wires on the other. That's the white you're
using for the ground).

3. Install a small subpanel in the shed, with an isolated neutral bus bar
(keep the neutral and ground separate).

4. Drive a ground rod outside the shed and connect it to the ground in
the
subpanel (6 gauge copper wire).

5. Install two 20A breakers in the subpanel. You'll have two 120V
circuits, one on each phase of the supply.

You could even install a 20A double pole breaker if you needed a 240V
outlet for something, though obviously you wouldn't be able to use
that and
the 120V circuits at the same time (you only have 20Amps coming in on the
12 gauge wires).
...

He has 5 wires, total...one 12/2 w/G another 12/2 w/o

Rather than all that which isn't compliant either (not supposed to have
multiple cables making up one circuit) he might as well just use the one
3-wire from a double-pole supply breaker and go to a box in the
outbuilding and then from there the internal circuits. He can have both
that way (assuming he uses an appropriate box, of course). He'll still
be limited to the overall capacity of the 12 AWG wire but sounds like
pretty small loads any way.

What he loses is that at the moment he does have two 20A circuits.

--
If he does that, he can only have 240 volt circuits. He'll have no neutral