While I suspected we didn't have the resources to obtain UL certification for the XTB products, I did pursue the possibility. Unfortunately, the expense was even higher than anticipated. Our production volume is just too low. Prices would have to be increased $50 to $100 to recover the cost, which would have a major negative impact on sales. Unless production is transferred to a large equipment manufacturer, UL certification is just not feasible.
I am not aware of anything that would prevent UL certification of any of these products. The safety components, such as the transformers and flame-retardant cases, all have UL ratings. And all components that see full line voltage are conservatively rated. Line voltage capacitors are rated for at least 160VAC, and 250VAC in the XTB-IIR. Units are fused to provide protection should either the isolation capacitors or MOVs fail. The transformer is impedance protected, and will open-circuit if there is a major internal failure. Special care was given to the printed circuit traces carrying full line voltage to provide maximum possible trace separation, well in excess of the UL requirements where possible. If there is a major electrical failure inside any of these products, the flame-retardant case is designed to prevent that from propagating beyond the unit itself.
While the XTB products are not likely to have a UL rating, they have been designed with operational safety in mind. But like all electrical devices that can dissipate heat, it is good practice to keep particularly combustible materials away from these devices. Signing the liability waiver is your acknowledgement that you accept responsibility for the proper operation of the units.
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