Simply replacing the first receptacle in the group with a GFCI receptacle, will provide protection to the entire group (if wired properly).

GFCI Receptacle

Locate the feeders

WARNING:

This procedure should only be carried out by persons with the proper tools and knowledge. And should be carried out with extreme caution.

When you open up the box containing the first receptacle in the group, you're going to notice two cables enter the box. One cable brings power from the breaker/fuse box (feeder), and the other carries power to the remainder of the circuit. You'll have to figure out which cable is which, so you know how to connect the GFCI receptacle.

1. Start by turning off the power at the breaker/fuse box.
2. Disconnect the receptacle, and position all the wires so that they will not contact each other or anything else conductive.
3. Turn the power back on.
4. Using a multi-, voltage or non-contact meter determine which set of wires is which. The feed from the breaker/fuse box will have power, while the line going to the rest of the circuit will not.
5. Mark the wires in some way, and turn the power back off.

WARNING:

If you got a voltage reading on more than one set of wires, STOP, do not follow the rest of these instructions. contact a local Electrician.

Connect the GFCI

On the GFCI receptacle you'll notice that one set of terminals is labeled "LINE", and the other is labeled "LOAD".

1. Connect the wires from the cable you marked as being from the breaker/fuse box, to the terminals labeled "LINE" (Black to brass, white to silver, green/bare to green/ground and the box if it's metal).
2. Connect the wires from the other cable to the terminals labeled "LOAD".
3. Install the receptacle into the box.
4. Turn the power on.
5. Press the Reset button on the GFCI receptacle.

WARNING:

If the receptacle will not reset, the wiring is connected incorrectly, or contains a fault. Contact an Electrician to complete the job.

GFCI Breaker

Alternatively, you can install a GFCI breaker to protect the entire circuit.

WARNING:

This procedure should only be carried out by persons with the proper tools and knowledge. And should be carried out with extreme caution.

1. Turn off the breaker.
2. Remove the black wire from the terminal on the breaker.
3. Locate the white "neutral" wire associated with the circuit (should originate from the same cable).
4. Remove the white "neutral" wire from the neutral bus bar.
5. Remove the breaker (Caution should be used not to touch the hot bus bar while the breaker is removed).
6. Install the GFCI breaker.
7. Connect the white wire from the GFCI breaker to the neutral bus bar.
8. Connect the white "neutral" wire from the circuit to the GFCI breaker.
9. Connect the black "hot" wire from the circuit to the GFCI breaker.
10. Turn the breaker on.

WARNING:

If the breaker will not reset, the wiring is connected incorrectly, or contains a fault. Contact an Electrician to complete the job.

Test the GFCI

Once the GFCI device is installed, it should be tested at least once a month to insure it's functioning properly.

1. Press the Test button.
2. Press the Reset button.

If the GFCI will not reset, the GFCI is bad, the wiring is incorrect, or there is a fault. Correct any faults, and/or install a new GFCI device.

Years ago I bought an older trailer like this.

All the outlets were 2-wire. Fortunately, all the runs back to the fuse box were fairly short. Back in the days when it was built it was assumed that all the neutrals would be connected to a ground bus in the box.

So we made sure they were bonded and attached to a utility company-provided ground rod.

We had to replace all the receptacles with 3-prong outlets. I stopped short of tying the ground to the neutral at the outlet, which meant that the ground leads ended up floating.

I understand PG&E's position, since they deal with the code as it exists today.

So you have the option of adding a ground lead for the particular outlet they will inspect and call it a day. Or, perhaps you want to provide grounds all around the unit.

I live in PG&E territory and find they are very safety-oriented. If their focus is just on that one fridge then adding a ground wire might be worth the effort.

Ground wires do not need to be insulated or run in conduit, but definitely run it all the way to an approved ground bus or rod.

Never rely on the structure itself to be grounded properly. It is sitting on rubber wheels, remember, and even if it is grounded at the box it would provide a much higher resistance path to ground than a run of copper wire can. Just think of how many structural panels are screwed together between the box and your outlet. Each one rusts over time. You get the picture.

Of all appliances I have owned, the one most prone to having a hot case seems to be refrigerators. So whether you get it from them or buy one on your own, you really should have a grounded outlet for it.

Good luck!