2 transformers / 1 switch / see diagram

sparkyjohn1 · Apr 29, 2014

Hi,
Just wondering if anyone could shed a bit of light on this subject..
As a domestic Spark,I don't have extensive knowledge of low voltage , and how it behaves during series and parallel configurations.. ( been a while since college..)...
I've come across a situation where i've been asked to retro-fit more L.E.D's to an existing circuit, but have to Install another driver to power them, as original one isn't man enough to take the extra load. This all sounds kosher, but customer as asked me to utilise the same switch. ( see diagram...)

I realise that there will be a possible solution to the issue, ( probably with use of a contactor.? ).. But would the diagram, be safe , If I installed it like that...
NOTE : original transformer cannot be removed due to voiding warranty ( it is fitted inside the body of the equipment..).

Please let me know your ideas..
Many thanks

[ElectriciansForums.net] 2 transformers / 1 switch / see diagram

Marvo · Apr 29, 2014

Switch the LV on the primary side rather than the ELV. Dont common together the outputs from two transformers or drivers you'll probably cause damage.

sparkyjohn1 · Apr 29, 2014

That was my concern mate,, .
You reckon move the switch directly after the mains input, then split to each tranny,?.
Its a micro-switch, probably only rated at extra low voltage.. would mains voltage kill the switch??

davesparks · Apr 29, 2014

You could install a different switch which is rated for the appropriate voltage on the mains side.

Or swap the switch for a DP switch to switch both outputs independantly.

sparkyjohn1 · Apr 29, 2014

Is it acceptable to use a Double Pole switch to switch 2 separate live's.. ? for 2 different lighting circuits? Rather than conventional method of switching live a neutral? would seem very odd wiring the switch like that..
Comment appreciated tho.

davesparks · Apr 30, 2014

I meant DP switch on the output side, no need for it on the input side.

Richard Burns · Apr 30, 2014

If you have access to the unswitched side can you not ignore the original completely and use a suitable supply transformer for the lot?

sparkyjohn1 · Apr 30, 2014

thanks for the reply,
thats the main reason I got the new tranny way more rated than the new L.E.D's that are to be installed.. Not sure if the connections on the original are sealed or moulded tho,,. I shall get back to you on that... Best idea so far tho,, Nice one... As far as the ELV splitting after the switch,, would it matter that there would be parallel circuits., ( current splitting etc.).. Or would the L.E.D's just draw what they need..??

Richard Burns · Apr 30, 2014

Generally the LEDs will take what they require however you are then you are into the type of LED you have: constant current or constant voltage.
If your LED is constant current and the others constant voltage there could be problems, but if you have matched your driver to the supplied driver it should be OK.