Flourescent ballasts, changeable?

[johnmf]

Ive got a 4ft 36 watt flourescent twin fitting where one of the ballasts has given up (figured this out by process of elimination.)

Ive also got a spare 6ft single fitting. The ballasts in each look more or less identical so im wondering whether its ok to use the good one in the fitting i want. Would save me the hassle of getting a new twin 4ft fitting which my wife is rather fond of.

Is there anything to watch out for when changing ballasts?

 

[333rocky333]

A 6ft is 70 watt so no good.

Buy a cheap single 4 ft and remove the ballast

 

[johnmf]

Thats scuppered me then, thought i might be ok using a higher rated ballast on lower rated tubes, just not other way round. Cheapo 4ft fitting it is then.

 

[333rocky333]

The choke limits the current allowed to the tube.
A 70w will allow excess current to the 36 w tube and will shorten the live of the tube and possibly just blow the filament instantly.
On the 36w choke you will see something like 0.37 amps on it somewhere compared with about 0.76 for the other 70 w one.

 

[ColJack]

http://home.howstuffworks.com/fluorescent-lamp6.htm

 

[Spark123]

http://www.tlc-direct.co.uk/Products/ZZAPslashLEC36LA502K.html