Published:
27 February 2015
Category:
Q&A
John asks this question, which concerns a kitchen LED downlight installation having one- and two-way switching circuits, where some of the LEDs glow even when power is removed. It has been answered by the Lighting Industry Association (LIA) (Theme – Lighting):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: I’ve recently installed 12 LED downlights with Saxby 3.5W GU10 lamps. Eight of the lamps are on a one-way switching circuit and four are on a two-way switched circuit - all in a kitchen and fed off the same circuit.
The four that are two-way switched glow when switched off. I have rewired the three C&E between the two switches but it made no difference.?
The live and switch wire are connected to the strappers L1 and L2. Live to L1, switch wire to L2. When both switches are in the Common/L1 position (OFF) there is no glow, but when in the Common/L2 position (OFF) all four lamps glow. The eight lamps switched one-way don't glow.
Is there a logical answer to this?
I contacted Saxby technical but they thought it was probably something in the wiring.
Answer: This is quite possibly an induction issue. In two-way circuits, we have seen and measured a small induction current which in the case of LEDs using such low power consumption can be enough to cause a glow - or in some cases a discharging flash every so often.
The answer is usually to include a dummy load in the circuit.
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