Abstract: The invention provides a method and apparatus for electronically testing the safety of sources of energy such as electrical circuits, in explosive atmospheres such as high risk mining situations, using an electronic spark tester (EST) in place of the known mechanical spark test apparatus (STA). The EST typically uses an analogue subsystem (5) and a digital subsystem (6) connected by a digital to analogue converter (7) and an analogue to digital connector (8) to apply a simulated spark load to the energy source and measure the time varying current response to that load.

Abstract: A combination AC receptacle and low voltage class 2 power units are provided in a standard single strap flush wall-mount outlet so that portable battery operated electronic devices may be charged without having to use a special AC charger. Ground fault circuit interrupter (GFCI) and/or arc fault circuit interrupter (AFCI) capabilities are also provided so that this combination AC receptacle and low voltage class 2 power units, e.g., USB receptacles, may used in occupancy locations requiring such protections under current electrical building codes. A standard wall cover plate is used to finish off installation of this flush wall-mount outlet into a wall outlet box. Also a data interface may be provided to allow a PDA or PC to control smart wiring systems through the USB receptacle.

Abstract: A combination AC receptacle and low voltage class 2 power units are provided in a standard single strap flush wall-mount outlet so that portable battery operated electronic devices may be charged without having to use a special AC charger. Ground fault circuit interrupter (GFCI) and/or arc fault circuit interrupter (AFCI) capabilities are also provided so that this combination AC receptacle and low voltage class 2 power units, e.g., USB receptacles, may used in occupancy locations requiring such protections under current electrical building codes. A standard wall cover plate is used to finish off installation of this flush wall-mount outlet into a wall outlet box. Also a data interface may be provided to allow a PDA or PC to control smart wiring systems through the USB receptacle.

Abstract: A soluble mono-alkyl Stannoic Acid/glycol liquid phase catalyst produced from the reaction of a mono-alkyl Stannoic Acid and a glycol at a temperature of from at least 180.degree. C., and its use in preparing high molecular weight polyester polymers.

Abstract: An improved process for preparing high molecular weight polyester polymers, such as poly(butylene terephthalate), an alkylene glycol and a di- or tricarboxylic acid by first preparing a pre-polymer in the form of uniform solid particles having an intrinsic viscosity of from 0.1 to about 0.3 dL/gm and a chemical composition which contains greater than a 1% stoichiometric excess of the alkylene glycol above the amount required to produce a high molecular weight polymer, and polymerizing the pre-polymer in the solid state.