From the FAQ's on the website, your "Radiant" model uses a dry resistance wire running through the tubes, which they say is not repairable!
- Dry Element technology: These models have a resistance-style wire cable that runs through all horizontal & vertical bars (note – many competitors only have horizontal bars that heat up!). The benefit is rapid heat-up time, regardless of the size – 10 to 15min. Note – heating cable cannot be repaired but is covered under the product warranty.
- Our Sirio, Quadro, Antus, Vega, Solo, Swivel & Radiant collections use this technology
An insulation test really requires a multifunction tester, or specialist high resistance tester using 120V or higher to do the test. An ordinary multimeter on the highest resistance range might give some indication whether there is leakage between the live connection and the metal tubes/ground connection, but your 'experiment' seems to have proven that already!
