fluorescent strip lighting does not switch off

Evening.

I recently fitted a fluorescent strip light in a garage for a friend.

I have wired correctly. Taken live from the CU to a connector in light fitting, then down to the switch and a switch line back to the light into the live return connector.
Obviously the neutral from the board to the light (nothing to the switch)
I tested by switching on and off, but occassional i'm told the light will not switch off?
Is there a reason why a fluorescent fitting would do this?
Such as damaged ballast or ignitor? as when they tried to fit themselves they 'shorted' the light fitting.
They had already discarded the fitting instructions and i am wonderering as they got an external weatherproof fitting do any of these come with timers, so as to be activated by a PIR? I haven't heard of any but then i assume they might be available?

Any help would be greatful
cheers
dan

When you turn it off, there should be no voltage at the terminals to the light. When there is no voltage at the terminals the light will go off.

If you have no voltage at the terminals and the light stays on then I would like to be your manager and will only want 20% of the gazillions of pounds you will make from generating electricity out of thin air.

Unless you have installed an emergency light fitting then I would respectfully suggest you have wired it up incorrectly.

maybe the switch is jiggered?

yeah no live to the light fitting once switched
replaced the connector in the fitting with a connector block as no spare live terminal to take a feed to a switch and then have the switch line return. so in effect wired up for singles not t&e.
Without the fitting manual how would i know it's an emergency fitting, i'd imagine there'd be a small recharegable in the fitting somewhere?

Not that small - about the same as 6 D cells at least.

Does the ballast look particularly large?

Does it have terminals for switched and permanent live?

When it's in the state of "won't go off" what happens if you cut the power to the whole garage? If it stays on it's got to be an emergency light, of it goes off then you've wired it wrongly or the switch is shagged.

thanks again.
I now think you're both right about the switch. It was fine when i tried, and he is now saying that it happens 'intermitantly' and does indeed go off when the mcb is turned off.
Confident it isn't wired up incorrectly as i say, when i was there it was fine and wired as i described earlier.
I'll get him to change the switch.
Thanks all

He will have buggered the switch when he first switched it on and it shorted out.

thanks, it was indeed the switch.
I was confused as he assured me he had bought a new replacement switch, trouble is he ahdn't fitted this one like he'd said!
Grrrrrr....