Cropping of Reed Switch Leads

Reed switch leads may need to be cropped for use in custom plastic housings, after soldering with external cables. Cropping the leads of a reed switch removes low reluctance iron and introduces high reluctance air into the magnetic circuit, much the same as adding resistance to an electrical circuit. The result is that a greater number of equivalent Operate AT is required to close a cropped reed switch. This also increases the release AT. This would mean that the actuating distance will decrease. More information can be found on our Reed Switch FAQ.

When cropping the leads of reed switches and reed sensors, extreme caution should be taken to ensure that shock is not transferred to the delicate glass to metal seals, as this could damage the hermetic seal integrity and even cause the reed blade gap to change. If only conventional methods of cropping are possible, it should be known that wire cutters transfer shock in both directions and may produce as much as 70g shock to the seal areas.

Although it is better for the Reed Switch manufacturer to supply reed switches cropped to the desired length using special tools, at some times, this may not be acceptable due to time constraints. In this case, it should be known that End nippers only transfer shock one way and cropping reed switch leads leads should be done after orienting the end nippers, as shown above. When end nippers are used, it is recommended to inspect 100% of the cropped reed switches under a microscope at 5x magnification, to check for any cracks or damage to the seals or other micro leads deformities that could result in early failures. It is also better to conduct magnet 100% distance checks after reed switch leads are cut, to ensure application compliance.