(b) The voltage source of spark tester shall maintain a minimum test potential of 6000 volts RMS under all normal conditions of leakage current.The core of a transformer and one end of its secondary winding shall be solidly connected to earth ground.A voltage source shall not be connected to more than one electrode.
(n) For the factory production continuity testing of a flexible light enclosure, it is the manufacturer’s choice whether to substitute either of the following for the test in (m):
a) Continuous eddy-current procedure complying with (o) and (p); or
b) Continuous differential capacitive-current procedure complying with (q).
(o) The eddy-current test arrangement shall include equipment that complies with each of the following:
a) The equipment is to apply current at one or several frequencies in the range of 1 – 125 kHz to a test coil for the purpose of inducing eddy currents in the conductor moving through the coil at production speed;
b) The equipment is to detect the variation in impedance of the test coil caused by each break in the conductor;
c) The equipment is to provide a visual indication to the operator.
(p) The longitudinal axis of the conductor is to be coincident with the electrical center of the test coil.The flexible light enclosure is to have little or no vibration as it passes through the test coil and is to clear the coil by a distance that is not greater than 1/2 inch (13 mm).Variations in the speed of the flexible light enclosure through the test coil are to be limited to plus 50 percent and minus whatever percentage (50 percent maximum) keeps the signal amplitude from falling below the level at which a break can be detected.Calibration without any wire in the test coil is to be made at least daily to check whether the equipment is functioning. The temperature along the length of the flexible light enclosure being tested is not to vary from the temperature at which the equipment was calibrated, balanced, and so forth unless the variations are gradual and are without hot or cold spots that cause false signals.
(q) The differential capacitive-current procedure shall include equipment that complies with each of the following:
a) The equipment is to be used in conjunction with a 1 – 3 kHz or higher-frequency spark tester;
b) Two pickup electrodes are to be located in tandem either along the portion of the conductor being tested that is moving from the grounded pay-off reel toward the spark electrode, or along the portion of the conductor being tested that is moving toward the grounded take-up reel from the spark electrode;
c) As each break in the conductor is passing from the first pickup electrode toward the second, the equipment is to detect the difference between the voltage capacitively coupled from the conductor under test to the pickup electrode nearest the spark electrode and the lower voltage coupled to the pickup electrode nearest the grounded reel; and
d) The equipment is to show a visual indication to the operator.