ASSOCIATED RESEARCH, INC., Lake Forest (near Chicago), Illinois
Hipot and Ground Bond Testers
Electrical safety compliance testing Instruments: hipot, IR, continuity, ground bond, leakage, power monitor.

SLAUGHTER TEST SYSTEMS, Ardmore, Oklahoma (mid-way between Dallas and Oklahoma City)
Surge Testers
Production surge testers for verification of insulation integrity in wirewound products.

THERMO SCIENTIFIC KEYTEK, Lowell, Massachusetts (northwest of Boston, near New Hampshire)
Surge Generators
Modular and multifunction systems for CE, UL, FCC, and other regulatory requirements.

TRANSIENT SPECIALISTS, INC., Western Springs (near Chicago), Illinois
Thermo KeyTek Equipment Rental and Used Equipment Sales