TJ/H2b Analytical Services, Inc.
- Offers analysis and consulting in diagnostic testing of oil, gas and insulating materials used in high-voltage electrical equipment. International contacts from their base in Sacramento, California.
- http://www.tjh2b.com/

Northern Technology and Testing
- Offers independent testing of dissolved gases, DGA, PCE, PCB, furan, metals and transformer fluid analysis for the electrical power industry, from Sacramento, California.
- http://www.nttworldwide.com/

Vasavi Electronics
- Fabricates automatic test equipment for transformers, coils , relays and cables.
- http://www.vasavi.com/

Hirst Magnetic Instruments Ltd.
- Manufacturer of magnetising, demagnetising, magnet calibration and magnet processing and magnetic measurements equipment.
- http://www.hirst-magnetics.com