CAST Niche Light (CNL1CB) and Deck Light (CDL1CB): Secondary Circuit Breaker or GFCI Trips

Mixed or wrong wiring polarity trips breakers on fixtures with SCB sockets

Issue

CAST Niche Light (CNL1CB) or Deck Light (CDL1CB), when mounted on a conductive and/or grounded surface causes secondary circuit breaker or GFCI receptacle to trip upon power-up.

Cause

Both these fixtures use Single Contact Bayonet (SCB) sockets. This type of socket has the neutral side of the contact (ribbed lead wire) connected to the base of the fixture. If the fixture is mounted to a conductive surface, then incorrect wiring can cause current to flow through the conductor to ground or to another fixture.

If the conductive surface is connected to a ground common to the power supply, then reversing the polarity of the fixture wiring may cause a current to flow to ground and trip the GFCI.

If more than one SCB fixture are mounted on the same conductive surface then the polarity of every fixture must match, otherwise a short circuit may result and the secondary circuit breaker will trip.

Remedy

To correct or prevent the above, always be sure to match wiring polarity of SCB fixtures when splicing lead wires together with a homerun wire (i.e. ribbed legs spliced together) and always connect the ribbed leg to the common terminal at the transformer.

(Document No. : Created on: 07/31/08 Last modified on: 07/31/08)

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