Using 5V Relay Modules for Lighting and Small Load Control

H

Henry Shaw

Member
Location
Hong Kong
Occupation
Engineer
Has anyone here used the common SRD-05VDC-SL-C relay modules in lighting or outlet control projects?

I know they’re rated for 10A, but in practice I’m not sure how reliable they are for switching small inductive loads (like fluorescent ballasts or small motors).

Do you treat them as fine for general lighting control, or avoid them in permanent installs?

Any issues with contacts welding or failing prematurely?

How do you handle NEC compliance when these modules are used in control circuits?

I’d love to hear some real-world experiences before I decide if they’re worth using.
 
Not something we would use, more of an electronics item since it's made for PC board mounting. To answer your question, the specs make it look like it would work for your application. What I would do is order a few samples and test them for yourself.

-Hal
 
I would only use relays from reputable manufacturers (OMRON, TE, Potter and Brumfield) and would probably go for a relay in a DIN or relay socket to allow for easier screw connections. PCB-mount relays are only designed to be used on a board. If you are intending to switch inductive loads, make sure the relay is rated for it. Welding is always a potential issue (which is why we tend to use contactors rather than relays); for one project the only way to protect against contact damage or welding was to turn on the relay at zero cross voltage, and turn it off at zero cross current. Made for some interesting circuitry and software, but it had to work up to 30A inductive/resistive/capacitive up to 347v and fit into a small package

Stay away from the Amazon/Ali Express relay boards (intended for Arduino and similar projects) as they often violate creepage and clearance rules and the traces are nowhere large enough for 10A... Those boards are also not NEC or UL compliant
 
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