I hired someone yesterday to install a gfci on the circuit that my pool lights and small backyard office are on. My home has a GTE sylvania box which uses those zinsco breakers and the gfci breaker for this panel is almost $300 each. So he ran a small box next to it, powered the box off the 20amp circuit and after installing the gfci breaker fed the original pool light wiring off it. However he did it, it didn't work properly and the gfi tripped whenever the power was turned back on. He basically gave up because he couldn't figure out why it wasn't working and he restored the wiring like it was before, but I want to figure out the problem and asked him to give me a sketch of the wiring he was attempting to set up. Here's my interpretation of what he wrote down:

http://img170.imageshack.us/img170/4079/gfcilayoutthatdidntworkfm0.jpg

Is there a problem with this set up that would cause the gfi circuit breaker to trip? Note that the 20 amp breaker that feeds the new small panel is not tripping.

If there's nothing wrong with this wiring layout, I'll know that there is something else I need to track down.

Well first of all a picture would really help us instead of a drawing. Second, why does it appear that there are two "Hot" leads coming from the GFCI breaker in the "B" or Sub panel.

Did he jumper from the Breaker "B" ox back to the Main Panel? If he did, did he remove all of the connections from the existing lights in the Main Panel ans splice them to the Wires from the "B" box.

The way a GFCI works is it monitors the difference of current between the Black (Hot) and the Neutral (Return) White. If there is a difference from 0.004 to 0.006 it will trip the breaker.

From you drawing it doesn't look like either the GFCI or the circuit is connected to the neutral. Maybe its just your drawing.
Why not just run a 20 amp circuit to the office, install a GFI outlet and let it protect the pool lights.

Paul,

The gfci breaker needs the factory white wire connected to the neutral bus, the drawing

Does not show that connection.

Well first of all a picture would really help us instead of a drawing. Second, why does it appear that there are two "Hot" leads coming from the GFCI breaker in the "B" or Sub panel.

Did he jumper from the Breaker "B" ox back to the Main Panel? If he did, did he remove all of the connections from the existing lights in the Main Panel ans splice them to the Wires from the "B" box.

The way a GFCI works is it monitors the difference of current between the Black (Hot) and the Neutral (Return) White. If there is a difference from 0.004 to 0.006 it will trip the breaker.

Here's a picture of the subpanel he added

http://img503.imageshack.us/img503/825/cimg0919ae8.jpg

You need to temporarily remove the green and the pigtail and check continuity between the box and the bar. If there is continuity, then that will explain it not working.

There is a screw between the two slots on the mounting bracket. I don't know if it's green or does it connect to the box. It could be a bonding screw and it would need to be removed if it is.

Ground is provided by the armoured cable.

I'd disconnect the white and the green that are connected to the bar and wirenut those two wires together. Should work if hypothesis is correct.

Paul,

As KISS indicated above, the Armored cable serves as the ground from the "B" panel to the Main Panel.

Neutral (White) and Ground (Green) should only meet up at the Main Panel.

Consider finding the green grounding screw or install a separate Grounding Bus. Although I do not see any screws in the "B" box to do this, but my image is not very clear.

If I'm seeing it correctly, he brought over a 4 wire connection. Red is serving as the HOT Source for the "B" box bus. It should also be connected to the Circuit Breaker on the Main Panel. Neutral is properly connected to the Breaker and the Breaker is properly connected to the Neutral.

The Black wire looks to be the Hot source Return to the Main Panel for connection to the wires going out to the lights.

From your initial drawing, it appears as though there are two wires to the light branch circuit.

Where is the Neutral that needs to be going to the lights?

..

Guys, the armor does NOT provide a ground since that looks like MC cable. The only way it could is if that were HCF rated MC cable.

That installation is NOT compliant! I see several issues.

I see issues too: The major one being the use of green for neutral.

What's the make and model of the sub-panel?

Paul,

Can you send us a picture of the other panel, so we can see how it is tied in ?