Induction and Dielectric Heating Equipment

Article 665 is for induction heating, which melts and hardens metal, and dielectric heating, which warms plastics and wood glue lines with radio-frequency energy. The hazards go beyond ordinary shock: the fields themselves can induce currents in metal objects and in people, and the RF voltages are high. So the article stresses shielding, interlocked guarding, and keeping the energized elements enclosed.

I respect these machines because the danger is partly invisible, a field you cannot see heating a ring or a tool near the coil. I make sure the guarding interlocks work, the enclosure shielding is intact, and the grounding is solid, then I keep loose metal and untrained people well clear of the work coil.

When it applies

Article 665 covers industrial induction and dielectric heating, machines that heat metal or plastic with high-frequency electromagnetic fields rather than a hot element. Because those fields and the associated voltages are intense, the article addresses the supply, shielding and enclosure of the RF section, and protecting workers from stray fields and from the high potentials inside.

Common mistakes

• Treating the RF output section like ordinary power wiring instead of following the manufacturer's shielding and grounding scheme.
• Leaving access panels or shields off during operation, which lets stray fields and exposed high voltage escape the enclosure.
• Ignoring bonding of the work coil and surrounding metal, which can heat or arc if left floating.

In the field

Around induction gear I respect the shielding as part of the safety system, not just cosmetic sheet metal. The high-frequency fields do not need contact to hurt you, so I never run one of these with a panel removed just to watch it work.