fluorescent lights

[tielboy]

How many 4ft x 4 fittings can I put on a two way switch. Obviously induction plays a part here.

 

[Spudmiester]

what is your switch rated at ? 5a, 10a, some grid switches can switch 20a (I think) .

 

[adnarim]

hi,

as tielboy states,dependent on switch rating,but you could if neccessary go down the road of using a contactor switched by the two way switch, to handle load,obviously depends on numbers of fittings you want to power up.

regards
adnarim

 

[Spudmiester]

hi,

as tielboy states,dependent on switch rating,but you could if neccessary go down the road of using a contactor switched by the two way switch, to handle load,obviously depends on numbers of fittings you want to power up.

regards
adnarim

Tielboy ???? WTF

 

[adnarim]

whoops! ,easily done.

 

[Spudmiester]

whoops! ,easily done.

No worries old chap, happens to us all !

 

[Adam W]

If I've done my sums right you can have 21 on a grid switch rated at 20A (most grid switches have silver plated contacts so can handle higher currents), which is quite a lot; usually lights will be switched in small groups to make the installation more flexible and save power.

 

[wattsup]

How many 4ft x 4 fittings can I put on a two way switch.
>>If I've done my sums right you can have 21 on a grid switch rated at 20A <<

Even if one two-way switch is in Manchester and the other in Nottingham?

There are unknowns, some things we know we think we know, the unknowns we know are known. If we were sure of the unknowns then we could be sure we know about the unknowns.
Some guy from the US -

ok ok, 400mm strappers...then the 20a switch will suffice -; (the 20a switch/s may be difficult to terminate

 

[Adam W]

Even if one two-way switch is in Manchester and the other in Nottingham?

Is that likely?
I thought the original poster may have been looking for a figure rather than a "well it depends", which is why I gave a ballpark figure.
Obviously it depends - switch rating, size and length of cable, presence of thermal insulation...
Perhaps I should have stipulated "up to 21".

 

[wattsup]

Nope very unlikely, but there are thousands of 100 mtr sheds all over the country, thousands of 50 mtr sheds. It is impossible to say without knowing the exact circuit switching arrangement. Thats all I was saying, you jumped in with 21, ballpark, doesn't work. For all we know this guy is now wiring a 50mtr shed, 21 line fittings on a 20a switch, if he uses 4mm no probs, what if he uses 1.5?.

He obviously has no clue by mentioning induction, he is more interested in of how many on a 2-way? Which leads me to believe he is wiring a shed/unit.

Of course he can have 200 fittings on a 2-way 5a switch, but not to your criteria

 

[Adam W]

I assumed by 4 x 4ft fittings he meant the type that drop into suspended ceilings in offices and the suchlike; my main point being the customer would generally want them switched in groups of 4 to 8, so without doing any calculations I would say a 2 way grid switch would do it even in 1.5.

 

[tielboy]

Thanks for the last comment. As for WATTSUP i was concerned for the large inrush of current from the fluorescent lights starting and a grid switch welding together. I know for a fact this has happened on a timer switch in the past.

 

[pope]

Well if you are worried about that then go down the contactor route in a few of the blocks of flats that i do communal lighting maintaince on we have a time switch flicking on a contactor flicking on many 28w 2d fittings so there are ways around anything.