wiring 2 pin mains plugs

[Bushbaby]

Hi All,
Can anyone advise on a simple method to determine the polarity when wiring a 2 pin plug for say a DAC90 or DAC90a?

Thanks

Rob

[tiv48]

short of puting a visable marker on the plug ie stick on a dot i dont.
nowadays i hardwire a lead to the on off switch and remove the wireing from the pins at the back.i have one in my collection that is original and because i dont intend to sell it it can stay like that.the set will of corse work wich ever way round the plug is inserted and if the back is on should be safe to use
rob t