Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have an uncased, unlabeled step-down transformer which converts 240 UK voltage to 112v (I have measured this with a meter). It weighs 1.5kg, is 10 x 8 x 10.5cms including the attached 2-pin US socket. How can I determine it's maximum VA rating?

share|improve this question
As a half decent approximation compare its weight against catalogue transformers of a similar size. – Andy aka May 10 '13 at 19:16
Do you have a picture of the transformer? Does it have a type plate? – jippie May 10 '13 at 19:21
Isn't UK mains 230V nowadays, like the rest of Europe? – Johan.A Sep 1 '13 at 9:07

You can never be sure without the datasheet of the manufacturer.

Rule of thumb for a non-welded iron EI core: 50 VA/kg.

This is a nice tool.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.