I was wondering if there are 3 or 4 lamp RS (electronic or magnetic) F40T12 ballasts because I'm thinking of putting an emergency ballast in my 4 lamp wrap around but there's already two ballasts in it at the moment (Advance 1x F40 HPF RS, Advance 2x F40 Electronic RS, one of the old ballasts got removed and got replaced by the single lamp one).

Advance made one model of F40T12 4-lamp ballast, but it was literally just two regular F40 rapid-start ballasts in the same enclosure, and took up the same amount of space as two standard ballasts, so that’s not really a solution to this dilemma. But what’s stopping you from just drilling some extra holes for a third ballast?

I don't know how to drill the holes, my dad probably wouldn't like that in the house, and I wouldn't have anyone to do it for me anyways

Those long ballasts must look a bit funny

Drilling thin metal sheet is easy, it can be done with low power battery drill and a suitable bit

If you dont want a hole, then mount 2 F40 ballasts, and some slotted metal rail such as a DIN rail between the ballast screws that are facing each other. To this rail you can attach the lighter components such as EM pack, battery, capacitors etc

Good bits for thinner sheets are the stepwise "christmass tree" drills - their long round section, with cutting just small step of the diameter at once uses to be sufficient to keep the hole clean

I was wondering if there are 3 or 4 lamp RS (electronic or magnetic) F40T12 ballasts because I'm thinking of putting an emergency ballast in my 4 lamp wrap around but there's already two ballasts in it at the moment (Advance 1x F40 HPF RS, Advance 2x F40 Electronic RS, one of the old ballasts got removed and got replaced by the single lamp one).

Yes, they do indeed exist. I saw some at an electrical supply shop around 25 years ago...don't remember who made them and haven't seen any since.

I believe the 3 and 4 lamp F40T12 ballasts were physically larger than the two lamp versions so one of them and a emergency ballast might not fit inside the same ballast channel.

Advance made a 4 lamp version: R-4S40-A-TP-AC
https://www.ebay.com/itm/205658765762

Judging from the wiring diagram it looks like it runs the lamps in two independent series pairs, it looks like the two sections can be fed separately for bi-level switching. So basically two two lamp F40 ballasts in the same enclosure. I'm kind of tempted to buy one to try out, they would be perfect inside some of my 8ft tandem F40 fixtures.

I'm not sure if a 3 lamp RS ballast was made but a 3 lamp F40 preheat ballast was made, they're not too easy to find now.

Thanks for the link, I might get it!

Yeah unfortunately it looks like I wouldn't be able to fit another ballast in with it