Atlas 30W T12 Green, and 30W T12 control gear experiments, 30W T8 choke

this is an experiment I have been meaning to conduct for a while now as contrary to popular belief 30W T8 and 30W T12 3ft tubes do not share the same electrical specifications

and I have often wondered how well a 30W T12 is being driven on a normal 30W T8 choke, and also if this is why some British 3ft 30W T12 tubes where dual marked 30W/40W

see a 30W T8 is rated at about 110V 330Ma, but a 30W T12 is rated at about 85V 430Ma, so I often wondered if the dual marked tubes where so marked to say "run me on a 40W Choke please"

so I finally got round to doing a couple tests and indeed these experiments show that a 30W T12 is under run somewhat on a 30W T8 choke and runs better on a 40W T12 choke


in this picture the tube is shown running on a 30W T8 choke and if we do some maths 84*0.37*0.85=26W (the 0.85 is the power factor of the actual tube itself and must be factored into the equation when calculating the power dissipation of a discharge lamp)

the main important thing however is to note the current is only 370Ma rather then the tubes rated 430Ma