Vibration Rating (Grms, IEC 60068 Test Fc and Fh)

A bare figure such as "10 G" carries no information. Sinusoidal 10 G peak and random 10 Grms are different by roughly a factor of three at the peaks, and neither says anything without the frequency band — machinery energy sits mostly below 200 Hz, so a sweep that starts at 100 Hz misses the range that breaks solder joints.

What each standard does

IEC 60068-2-6 (Test Fc, sinusoidal vibration) provides a standard procedure for determining whether an item withstands specified severities. It supplies the method; the severity is chosen by whoever commissions the test.

IEC 60068-2-64 (Test Fh, broadband random vibration) does the same for random excitation, defined by a power spectral density curve rather than a single amplitude.

ISO 16750-3 specifies mechanical loads by mounting location on the vehicle — a cab-mounted lamp and an engine-mounted one are graded differently. SAE J1455 is a Recommended Practice covering on- and off-highway trucks, construction equipment and agricultural equipment including implements; it is guidance, not a pass or fail standard.

There is no vibration standard written specifically for work lamps. Any supplier claim of the form "meets the work lamp vibration standard" is describing something that does not exist.

How to read a supplier figure

A complete statement looks like this: tested to IEC 60068-2-64, 15.3 Grms over 24 to 2000 Hz, three axes, plus 60 G shock. Nordic Lights publishes its work lamp figures in that form. Ask for the level with its statistical basis, the band, the axes, the duration, the pass criteria and the report number. A single G value with none of that cannot be compared between brands.

Vibration resistance is also a construction question rather than a test result: see potted driver for the encapsulation that determines whether a lamp survives the test at all.