Shore power cables

[Wanderlust61]

I have a 1975 Argosy trailer. I have two cables coming out from the back. One has 10/3 Type ST 600 volt for travel trailer use : 30 amp stamped on it. I can use that cable. The other cable has both ends cut off. It has Polar/solar 10/4 SEC W A 105 C stamped on it. What is this cable for?

[Jammer]

I would guess it was adapted to whatever purpose by a previous owner. 10/4 cables are widely used for 3 phase industrial equipment, and it was probably a leftover piece from something.

[klattu]

Maybe it was tied into a generator ?

[TG Twinkie]

How long is the 10/4 cable? If it is of useable length you can put new ends on it. Just use the Black; White and Green conductors.
The 4 conductor cables were also used for single phase 240 volt devices such as welders. Black=Hot; Red=Hot; White=Neutral; Green=Ground.

[JFScheck]

Perhaps connected to a charging system via the batteries and off season - where does it terminate in the breaker box?

Maybe it had a standard 15 volt 20 amp cord connected vice using an adapter with the other cable?

Odd....