In article ,
David writes:
I am trying to fault find a fluorescent light on the 12V circuit in our
motor home.

What size fluorescent tube are you thinking of?

I would look for LED lighting. In particular, LED retrofits for 12V
electronic transformers will just work without needing anything else.

Opinion seems mixed, but there are several postings which claim that these
are actually 240v AC lights with a built in inverter so that they can run
off 12V.

That seems unlikely to me. It would make the unit unnecessarily
expensive and reduce efficiency.

There is certainly a lot of circuitry inside.

Firstly, do camper/caravan/boat 12V fluorescents usually run at 240V with
a built in inverter (or sometimes)?

No, they ure just electronic ballasts (which use an inverter to drive
the tube directly.) They are usually nowhere near as good as mains
electronic ballasts though.

Secondly if so is there usually clear marking of the 12V and 240V parts?

I don't particularly want to probe a 240V AC circuit with the 50V DC part
of my little multi-meter.

A 12V electronic ballast may well produce in excess of 240V (particularly
cheaper circuit designs) to start the fluorescent tube.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]