• Welcome to the new forum. We're now hosted on ElectriciansForums.net rather than ElectriciansForums.co.uk - Chat about the forum upgrade by CLICKING HERE

Welcome to our Electrical Forum - We started out providing electrical advice just for the UK - But now we have specific advice for the USA too! - Register for free and share American Electrical Advice.

Discuss Current generation under control in the Electrical Forum area at ElectriciansForums.net


Regular EF Member
You've all seen people on YouTube overloading twin and earth cables, JW etc...

How are they generating current and how are they able to control that generation?

Lucien Nunes

Mercury Arc Rectifier
Respected Member
A cheap stick welder gives you a stepdown transformer with a secondary good for 100-200A. That has its own current control (using a magnetic shunt operated by the handwheel) but it's not that controllable.

Another way to get heavy current at very low voltage is to make your own stepdown. Wrapping a few turns of heavy cable through the open centre will create a very low voltage, high current secondary. E.g. a 500VA tranny works at around 2 turns per volt, so two turns of 25mm² will give you a source of 100A or so at 4V. It won't be a perfect transformer because such a sparse winding won't couple well, but it will work. You can make a better job by unwinding the original secondary and filling the space with multiple paralleled cables. 4V is sufficient to pump that 100A through any object under test up to 0.04Ω.

The adjustment can then be achieved, as with the welder, using a separate variable voltage transformer a.k.a. Variac.
  • Like
Reactions: DPG

Electrician Talk

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
Electrical 2 Go - Electrical Supplier and Electrical Wholesalers
Electrical Insurance
ElectriciansForums.net (formerly known as ElectriciansForums.co.uk) was setup in April 2006 to provide free electrical advice to both professional and DIY electricians. Whether seeking advice for auto electrics, trying to find electrical installation condition reports (EICR) form downloads, or whether you're here just to talk to other electricians; we've been a first-choice website for tens of thousands of sparkies for well over a decade.