For the connection from the socket to some connection block (all covered inside of the fixture), the TGGT will be OK.
The TGGT wires are intended just for internal wiring of high temperature things and do offer only basic insulation (so need to be covered). Plus are very mechanically fragile. So these are to be used really only around the hot socket and completely covered either by wiring inside of the stand tube or other cover.
Then for the cord itself I would use the European standard 250V (but that means designed robustness above 4kV for short time, the accumulated pulse time for the high voltage won't be longer than minutes over a 10 year fixture life period) 3-wire, double insulated cord.
The thing is, even though "277V" rated cables will electrically suffice too, such rating is available in a convenient format practical for home use as mains appliance cords for 230V markets.


Or you may do something a bit different:
Deactivate the ignitor within the ballast and then use a superimposed ignitor (European type will work well) placed inside of the lamp base or so. With that the cord won't be exposed to the ignition pulses at all...

If you are using an electronic ballast, the standard lamp cord you're using now should be perfectly fine as electronic ballasts will not continuously run the ignitor after a power interruption. Nearly all electronic ballasts ive seen or worked with delay the ignitor for several minutes (to allow lamp to cool) before hot restriking. Also ive seen plenty of UL approved remotely ballasted PSMH fixtures that use regular 105 C SJOO cord between ballast and lamp. So the insulation breakdown is clearly not even really an issue in the first place. I think youll be fine with your current lamp cord

The electronic ballast is much better noise wise and flicker wise. It also runs cooler than the magnetic did. I have not gotten around to getting TGGT wire, but we'll see. The calculated pulse is easier on the wire than the constant pulse from a standard igniter. I'm currently searching for a high CRI lamp to use, but I still have to visit one electrical supply counter to see if they can get me one. They sell GE.

When time permits (hopefully soon), I'll take pictures so you can see what I'm up to.

"Lamp cord" is definitely not ok, it is thin single isolation

Yes, didn't think of that one. I will, however, wait until it is complete to see if there is any interference with any other machine in the house before adding something to reduce it.

Regarding a ballast, I have a magnetic ballast in there at the moment. Unfortunately, I misplaced the mounting hardware so it is loose in the bottom of the junction box for now. The vibration is such that it is VERY noisy, something that could probably be cured with proper mounting. I used it twice, and the flicker is noticeable and could get annoying. I am somewhat sensitive to flicker (the flicker from fluorescents on magnetic ballasts don't bother me, however, only on HID and LED). Because of those two factors, I am waiting for an electronic ballast from eBay (Universal). It should quiet it down and stop the noticeable flicker. I imagine that an electronic ballast could make some interference that would inhibit FM reception, but I'll wait and see before making corrective actions.

There are stores around here that have changed to electronic T8 (some years ago, some recently) and others have changed to LED. I have noticed that when I am listening to FM radio in the car and I go by those stores, the reception is problematic. It didn't happen when those stores were magnetic. However, we're talking about lots (100's) of ballasts in the stores compared to one lowly 50W MH ballast in my house. I'll keep you posted.

Add insulation for sound proofing, And rubber shocks for vibration stopping.