In article , Andy Wade
writes
fred wrote:

Only 5% increase in impedance on 1.5mm2 @ 125k

Only 5% increase in *resistance* due to skin effect, perhaps, but a huge
increase in *impedance* due to the inductive reactance...

You're quite right about the inductance, I was just dissing the skin effect
theory.

I've just had a look at a the spec for one of the TLC transformers and it is a
35k switcher which would improve things quite a bit, splitting the load over
a couple of cables would help too.

Switching to adjacent cores of a triple + earth makes only a little difference
due to the Ln (or Log) term in the ratio of radius to spacing, I got a
reduction of only 15% there.

So, replacing the transformers with 35kHz models and splitting the load
into 2 T/E (or similar) feeds should reduce the inductive drop to 0.75V. That
drop is at 90deg phase and lossless so the lamps should actually close to
12V.

The data I looked at was for the Intram Barwell models on this page:
http://www.tlc-direct.co.uk/Main_Ind.../Lighting_Tran
sformers/index.html

As and aside, I'm a bit taken aback that this is an issue at all as this can't
be an uncommon situation and this is the first word of it I've ever seen on
the group, there's always a first time I suppose.
--
fred
Plusnet - I hope you like vanilla