On Sun, 27 Nov 2016 09:45:32 +1100, "Rod Speed"
wrote:

[snip]

http://www.ebay.co.uk/itm/3019340747...%3AMEBIDX%3AIT

Thanks. That was exactly my concern. I thought that the load and the
coils on a transformer had to be balanced and thefore to substitute
48W for 540W would damage the transformer. I'm sure that overloading
a transformer can cause damage. What I don't know is whether
underloading can cause damage.

No it wont. The worst that might happen is that the voltage is higher
than with all halogens and that might well see a halogen still left in
that circuit not last as long as it would normally do, but you say that
you don't want to run it with one halogen per transformer anyway,

Could I whip out all the halogen bulbs and check the voltage with a
voltmeter (ie, no load) to find out what the maximum voltage might be?
Is there then a tolerance in the LEDs to consider?