I have just installed a low voltage halogen lighting system in my converted office - the type that uses flexible cable tracking suspended from the ceiling. From the twin track hang five 12v 20W MR16s (in parallel). The track is powered by a heavy toroidal transformer. The supply is taken directly from a secondary 2-way CU serving only this room.
In fact I have two complete track systems (i.e. five on the left and five on the right) each sytem with a separate transformer. I have linked the two transformers together and run the power from one light switch to them both.
The problem: when both transformers are connected, the 6A MCB trips (not every time but far too frequently). However, when only one transformer is connected (left or right) it's fine.
The only aspect of the circuit I am not sure about is that both transformers run off the same switch. If these were two 60W bulbs in two bulbholders, I would expect no problem. But is this an inappropriate way to connect the transformers? Should I run each from a separate switch instead?