No... but thanks for the chuckle!

Yosemite has never run across cable that fits this use. Has anyone else? Remotely-mounted ballasts are part of my life every day, but I suspect that it is done in conduit in every case.

These luminaries don't already have ballasts?

If these luminaries are self-contained fluorescent lamp fixtures, the ballast is mounted within the metal fixture and is already properly grounded to the fixture.

The fixture's lamp reflector is also grounded to the ballast and, most importantly, the incoming AC ground, which plays a very important role in striking the arc through lamp through the capacitance between the lamp and reflector and ionizing the mercury vapor gas.

The ballast's secondary wiring length is also figured into the equation. The secondary wiring size, length, and temp rating are also part of the UL listing and changes to it would obviously negate any UL listing if this is a concern or requirement.

If these are some other type of luminaries, then there may be exceptions to all this but the mfg should provide the requirements in a data sheet.

I apologize if I made assumptions as to what you are attempting to do - but I really did think your post was somewhat tongue-in-cheek.

Watch out for voltage ratings also.

Striking voltages are rather high (even though of limited current).

Sorry about the "luminaries" thing. I think that I had a spel checker problem with an application that does not have luminaires in its dictionary.

No, it was not a tongue-in-cheek question. I wish it was :-( I dunno why two, single-ballast luminaires were installed right next to each other. If I have to buy two replacement ballasts, it will almost certainly be less expensive to just replace them with two-lamp luminaires. They are just strips and recessed so they don't have to be fancy. I am talking about 8 lamps here so it is not a really big deal. I just like to do things on the best practical budget.

Any grounding issue should be solved by the ground conductor run from one luminaire to the adjacent one. I doubt that I will do this with conduit though I happen to have the tools and materials lying around. I really don't know what I am doing with them.

FYI, the GE electronic, programmed-start ballasts that I have on hand have 18 ft. remote mounting limits with 18 AWG wire. Some are 1-2 lamp and some are 3-4 lamp.

Thanks for all of your comments!

"E electronic, programmed-start ballasts that I have on hand have 18 ft. remote mounting limits with 18 AWG wire."

Wire gauge is determined by current, insulation thickness by voltage.

Fixture wires are often VERY specific to the application.

All this trouble to save $15 on a ballast? I would usually recommend that you just replace the entire fixture with a 2 lamp fixture, but that will cost more than $15.

Think about it. If there were suitable cable and someone could steer me to it, I'd be there with a couple of cable clamps and a couple of feet of cable. That is not much trouble at all.

If they are so close together, can you not just install a 1/2" nipple (chase, short, offset or otherwise) between the fixtures? If so, as long as the ballast wires are long enough to reach their corresponding tombstone leads, I don't see a problem.