UL 1563 BULLETIN

Abstract

Scope: Background The requirements for switches and controls (Section 36), normal temperature regulation (Section 35.4), temperature-limiting controls (Section 36) and heater protection (Sections 37.4) originally reflected the use of electromechanical controls complying with UL 873. Later, the necessary parameters for the specification of controls evaluated to UL 60730-1 and its Part 2’s were added (Tables 35.1, 36.1 and 37.1). These parameter specifications allowed for controls that were either electronic or electromechanical. All these options basically assume the control is a separate component purchased from a control manufacturer. This arrangement has historically worked well for the controls used in spas. UL 1563 is also the basic standard used for swimming pool and spa water treatment equipment. These types of products frequently do not have circuits that are part of controls purchased from a control manufacturer. The circuits are specifically designed only for use in that particular product. These products also have other safety functions than the heater/water-temperature related functions of spa controls. Manufacturers have requested electronic circuits requirements be added to UL 1563 as another option to controls evaluated to UL 873 or the UL 60730 family of standards. Consideration was given to adding circuits requirements based on those in the Standard for Industrial Control Equipment, UL 508. The various circuits options in that standard reflect voltage and available power limits of Class 2 circuits in Article 725 of the National Electrical Code ANSI/NFPA 70-2017. After consideration of the matter UL believes the circuit options in UL 508 reflect a much higher circuit power level than is used in spas and water treatment equipment. The UL 508 electronic circuit options also mandate the use of an “industrial grade” enclosure around the circuit to contain molten particles from component faults. UL believes the best option for circuits requirements should be based on those of the basic international appliance standard, IEC 60335-1. These requirements allow for essentially any type of circuit, whether an operating control or a control for protection from defined appliance abnormal operation or component faults. The typical motor protection and heater/water-temperature control functions of spas could also be evaluated using these requirements. UL therefore proposes UL 1563 can be expanded to detail requirements for all types of electronic circuits. To accomplish this objective, UL proposes to add a set of requirements for electronic circuits based on those specified in the Standard for Safety of Household and Similar Electrical Appliances, Part 1: General Requirements, UL 60335-1.