Vintage trailer with two prong outlets

[55AS]

My new to me 1955 FC is set up with A/C electrical system wired with no green/ground wire. All outlets are two prong. Instead of main breakers, the shore power receptacle is connected to four branch circuits protected by 15 amp screw in glass fuses. There is no 12 volt system.
At some point, I will add an all in one converter to handle AC and DC power distribution but in the short term I just want to connect a modern shore power cord and receptacle in order to run AC items in the trailer. I have a 30 amp outlet in my garage that was used for my previous trailer which is on a GFCI circuit.
Basic questions:
1. Should I connect the new Shore Power receptacle green wire to my frame?
2. Will the GFCI in my garage trip?
3. If I replace two prong outlets with three prong should they be GFCI outlets?
4. Should I ground the new outlets to the frame?
5. In the interim, should I ground appliances like the electric water heater?

[Melody Ranch]

Just plug in the 15 AMP cord from the house to the trailer. Those fuses will give you fused protection. All the outlets will be powered. Your GFCI at the house outlet will only activate if your have that short in the trailer. Why not do it right. cut the fuses out, replace with new blade fuses, put in a 125$ converter and a small 4 space circuit breaker panel. A new 30 AMP shore power connector , replace the outlets inside with new 3 prong plugs and your done. Then there is the wiring condition situation....got mice?

[55AS]

No converter yet, but did install a new 30 amp receptacle and started replacing 2 prong outlets with 3 prong. Shell is grounded through shore power, which makes ground connections simple. The hardest part so far is enlarging holes in shell to fit larger outlets.

[TG Twinkie]

Connecting the ground terminal of each outlet to a clean spot on the skin or frame is better than not connecting it at all. Replacement of the 120 volt panel along with a new converter and modern fuse block is recommended.
Be sure to connect the ground buss in the new panel to the frame/skin. Do NOT ground the neutral buss.


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[55AS]

Thanks. Will do that after more urgent tasks like plumbing.

[Ampman]

If your relying on the shell/frame work for a ground path you might compromise personal protection. Mainly due to corrosion, loose rivets or sealant between the outlet site and frame ground attachment point. Ground to the shell/frame at each outlet but also use GFCI outlets or GFCI breakers if you replace the main panel. The GFCI's don't rely on a solid ground for protection but sense and trip based on the current value between the hot and neutral. They are cheap and work. They can and will save you from electrical hazards when there is no ground conductor available. That goes for old two wire house wiring as well.


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[Jammer]

Originally Posted by BambiTex

1. Should I connect the new Shore Power receptacle green wire to my frame?

Yes, that is what is done in new trailers, in essence. The accepted practice is to run the green wire to the ground bar in the panel, and also run a wire from the ground bar in the panel to the frame. Your old fuse box probably doesn't have enough room for a ground bar, and no harm is done by grounding the frame.

2. Will the GFCI in my garage trip?

Only if there is a short between neutral and the frame. It is possible that something like that was done deliberately, and also possible that it was done accidentally. If you get nuisance trips, you should find the short and fix it.

3. If I replace two prong outlets with three prong should they be GFCI outlets?

If it were my trailer I would leave the two prong outlets, and instead upgrade the fuse box to a breaker panel with GFCI breakers for the circuits that serve outlet strings.

You may find that GFCI outlets will not fit.

4. Should I ground the new outlets to the frame?

There's no good answer, which is why I wouldn't use 3 prong outlets unless I had also rewired so that a reliable ground is available.

It's pretty unusual to need a 3 prong outlet while camping. For a while I had a space heater with a metal chassis that required one, and I rented the "rug doctor" once and used it in my trailer, which required one. The usual things, toasters, laptops, phone chargers, holiday lights, hair dryers, don't use it.

5. In the interim, should I ground appliances like the electric water heater?

No good answer. 1950s wiring practice was to bond major stationary appliances to the frame or (copper) plumbing, or connect them using armored cable (BX), which sort of grounded them but not really.