RS transformer info

[Bushbaby]

Readings are as follows (set on AC with 250v across 2 thick yellow leads):
Red to red (marked as 250v) - 516v
Red to thin black - 260v
Thin blue to thin black - 135v
Thick green to thick blue - 5.6v
Thick green to thick white - 1.2v
Thick blue to thick white - 6.8v
Grey to grey - 16.8v

I've just realised I haven't measured thin white to what???

I have measured current at virtually 0uA across any leads (assume no current being drawn?

Comment please.

Thanks

Rob