Yep this doesn't like reverse polarity! One way round, presumably live on ballast side, tube fires without hesitation! Other way round it just won't strike! Do the Netalines behave this way?

This was actually documented in the instructions! You have to try it both ways for optimum starting performance, you want the ballast on the neutral as it runs the whole length of the tube and should be at earth potential. The Netalines have an artificial earth (small resistor with high resistance) between the neutral and metal body so if they're not earthed the metal body of the fitting is still at earth pottential and a glow discharge can form between the live electrode and tube wall.

Ha! I can remember my Dad cursing a 2 foot one of these we had in the kitchen as it was always playing up! Bet he had it in the wrong way round!

Lol he musta done. The other alternative is an IRS metal stripe tube for really reliable starting!

Wonder if that resistor causes any problem with RCDs? It should still be live to the ballast as if you ballast the neutral it will no longer be at earth potential!??

Shouldn't think so Kev. This fitting has only a connection to L and N, nothing to the protective earth. Just appears as a resistor strung between phase and neutral as far as the circuit and RCD is concerned.

I meant with the netaline that Eliot said about above?

Good point, I'm not sure what the value of the resistor is, I could go check. It's wired between the neutral and metal of the fitting, much like those 'artificial earths' in the Thorn catalogues, just there for reliable starting.

The 4-foot 1-lamp (low-power factor) rapid-start ballasts here don't like reverse polarity (especially if the fitting is un-earthed), you'll just end up with a pair of dim glowing ends..

I never actually owned one of these, but one thing use to strike me as odd, if, lets say, you BC batten was slightly out of line, then the whole fitting would not have been in a perfect straight line to the angles of the ceiling!

The BC plug allows for it to twisted for adjustment of the angle. I had a 2 ft diffused model and it could take some perseverance to get the adjustment right on a pendant!