Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

How do I choose a suitable power source for manual metal arc (MMA) welding?


Frequently Asked Questions

For AC operation, the no-load voltage is important and some electrodes, particularly the basic types, may require 70 to 80V (AC).

The welding current level is determined by the size of the electrode and the operating range for typical electrode sizes are given in Fig.1. As a rule of thumb, when choosing a suitable power source of adequate capacity, an electrode will require approximately 40A per millimetre (diameter). As an example, for the commonly used electrode size of 4mm, with an operating range of 140 to 180A, the power source should have a current capacity of at least 200A at an appropriate duty cycle ie, 20%, 35% or 60%, depending on the type of work.

Extracted from an article entitled 'Let's get technical - choosing an arc welding power source' by W Lucas and G Melton, published in Welding & Metal Fabrication, Vol.67, No.4, May 1999, pp.18-21. (Publishers - dmg BusinessMedia Ltd, Redhill, Surrey, UK -

For more information, please contact us.

For more information please email: