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Can I use a SSR for switching a fluorescent light on or off? Specifically, can the SSR last for a long time, and can it withstand a very large number of on/off switchings? I would also appreciate a sample circuit related to this, or references.

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1 Answer 1

Yes, some people use a solid-state relay (SSR) to switch a fluorescent light on and off. "Control Fluorescent Lights with a Laser Pointer and an Arduino" (and some SSRs)(a); "SSR to switch a·fluorescent light"(b), etc.

Older fluorescent lights draw 5 to 10 times their long-term average current for many seconds when "striking" the bulb at first turn on. (c d) So solid-state relays that are inadequately rated for only 2 or 3 times that long-term average current will fail pretty quickly. That may explain why many people (e f) say we should avoid using SSRs for fluorescent lights.

If you get a solid-state relay that is rated to handle that full striking current, then there's no mechanical bits to wear out and the SSR should last for a long time. For example, the manufacturer of Releco relays seems to think driving a "2 A fluorescent bulb" requires a SSR rated at 3 A. g h i

A few fluorescent light ballasts have a "control" input to turn it on and off directly, which may work better than completely connecting and disconnecting the power.(g h j)

I'm assuming you want to turn it on for a while, then turn it off for at least a few minutes, then later turn it on for a while. "Dimming" a fluorescent light by rapidly turning it on and off many times a second is a completely different question. (Do we have a question here on that topic, or am I mis-remembering How do you dim a streetlight bulb? ?)

You might consider some off-the-shelf gadget designed for turning on and off fluorescent lights remotely. h i j k

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protected by markrages Sep 11 '12 at 18:04

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