On Mon, Sep 28, 2015 at 12:18 PM, wrote: > Step 1: From the above I take it you are using 4 core screened cable > inside a metal pipe. Ensure the cable cannot touch the pipe (i.e. is > sheathed all the way), but have the braid connected to the pipe at the to= p > (outside world) end. The metal pipe should extend as far as possible, > ideally right up to the potted block. > One other thing I don't think I've seen mentioned is to use screened twisted pairs rather than just plain 4 core screened. That should provide significantly greater protection from external EMI. As most others are suggesting I'd certainly start with sorting out your cabling and passive protection before adding any protective components. Chris --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .