A while back I replaced 32 six foot 70 watt fluorescent tubes in my main workshop with ' 24 watt LED replacement tubes' type LTT6224HDL from TLC Electrical at about £13 each inc vat. The light level was at least as good if not better but I wasn't convinced regarding the energy savings (I have an Owl energy monitor on the power feed - indicated savings didn't seem as good as expected if any !)
Now I have another workshop with 28 six foot 70 watt tubes which I'd considered replacing but the price tag of £376 made me hesitate and take some measurements on the two workshops:
Main Shop 32 LEDs illuminated - current drawn - 11.8 amps voltage 235 gives 2773 watts or 86 watts per (24 watt!!!!) tube
Welding Shop 25 six foot 70 watt fluorescent tubes illuminated - current drawn 9.3 amps dropping to 8.5 amps when tubes warm up gives 1997.5 watts or 79.9 watts per tube
(I am measuring current using a Fluke 376 clamp meter that has always checked spot on against other instruments.)
So what the heck is going on? Apparently the new "24 watt" tubes are actually drawing more in terms of amps than the original fluorescent tubes. Supply voltage is a consistent 235 in both shops - am I seeing some weird power factor effect ? Being 'LED Replacement Tubes' the choke is still in series inside the fittings (which are up in the gods and virtually impossible to get at) but surely a choke in series with an AC load can only decrease the current not increase it.
Now I have another workshop with 28 six foot 70 watt tubes which I'd considered replacing but the price tag of £376 made me hesitate and take some measurements on the two workshops:
Main Shop 32 LEDs illuminated - current drawn - 11.8 amps voltage 235 gives 2773 watts or 86 watts per (24 watt!!!!) tube
Welding Shop 25 six foot 70 watt fluorescent tubes illuminated - current drawn 9.3 amps dropping to 8.5 amps when tubes warm up gives 1997.5 watts or 79.9 watts per tube
(I am measuring current using a Fluke 376 clamp meter that has always checked spot on against other instruments.)
So what the heck is going on? Apparently the new "24 watt" tubes are actually drawing more in terms of amps than the original fluorescent tubes. Supply voltage is a consistent 235 in both shops - am I seeing some weird power factor effect ? Being 'LED Replacement Tubes' the choke is still in series inside the fittings (which are up in the gods and virtually impossible to get at) but surely a choke in series with an AC load can only decrease the current not increase it.