High Frequency Loadings

[Lectrician]

What do most people use as a rule when calculating lighting loads?

For old switch start the worst case was to multiply by 1.8 - it never used to need quite that much TBH though! What is the best figure to use for HF fittings?

Trying to decide how many 4x18 T8 lamps I can happily stick on a std 6amp cct....

 

[Spark123]

OK, I'll stick my head in the fire
Something in the back of my mind makes me think that you don't need to de-rate for HF fittings.

 

[DetlefSchmitz]

De-rating is largely necessitated by a poor power factor. So... halve the PF and the actual current is double what you expected from I * V = W.

I always wondered though, whether there was also some recognition that disconnecting an inductive load was harder on the switch contacts...

So check the PF of the equipment and proceed accordingly.

 

[Lectrician]

I got some data from Tridonic.

They have recommended qty's of fittings per mcb rating. They take into consideration the fact that hf lamps will all turn on instantaneously as opposed to switch starts where surges are almost spread out.

 

[Spark123]

Not so much the startup surge, the wire wound ballast type consume a fair bit more power for a given wattage tube than HF fittings. I have seen some units which lower the supply voltage to the old type in an attempt to save power.