The other question to ask...is this a one-off design or production? PLC's = do this all the time, running meters of wiring inside industrial environmen= ts, or worse...and the input is generally opto isolated. You can look at z= ener barriers, used for explosion proof applications too. If it was me, I = would look at using something like the OPTO22 devices to interface with the= outside, or even use a small PLC that's designed to do exactly that....DL0= 9 for around $100, everything is built in. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= embedded systems Sent: Sunday, May 17, 2015 10:19 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] Suggested protection for outside wiring? I forgot, in one of my last designs I used with success the ADUM isopower = at 5KV isolation (very expensive as I mentioned before) http://www.analog.c= om/en/products/interface-isolation/isolation/isopower.html#isopower On Sun, May 17, 2015 at 12:50 PM, embedded systems wrote: > Harold, > opto couplers are a good idea up to 10KV isolation. Isolated supply at > 10KV it's usually expensive but up to 1KV it's easy to find: > > http://www.newark.com/recom-power/roe-0505s/dc-dc-converter-1w-5v-0-2a > -sip/dp/63X9545 Buried cable is less susceptible to lighting. I will > not be extremely worried but depends what do you have at the end. > > Vasile > > > On Sat, May 16, 2015 at 8:39 PM, Harold Hallikainen < > harold@hallikainen.org> wrote: > >> I'm working on an application where contact closures will be sensed >> by a PIC inside a building, but the contacts are outside (perhaps >> tens of meters away). What sort of protection for the inputs is >> suggested? What sort of protection is required by regulatory >> standards for equipment connecting to outside wiring? The outside >> wiring would likely be buried, but lightning could still induce >> currents into buried cables. Opto couplers are one way to get the >> isolation, but then you have to power the LEDs with an isolated supply. = Ideas? >> >> Thanks! >> >> Harold >> >> >> >> -- >> FCC Rules Updated Daily at http://www.hallikainen.com - Advertising >> opportunities available! >> Not sent from an iPhone. >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t ________________________________ PLEASE NOTE: The information contained in this electronic mail message is i= ntended only for the use of the designated recipient(s) named above. If the= reader of this message is not the intended recipient, you are hereby notif= ied that you have received this message in error and that any review, disse= mination, distribution, or copying of this message is strictly prohibited. = If you have received this communication in error, please notify the sender = by telephone or e-mail (as shown above) immediately and destroy any and all= copies of this message in your possession (whether hard copies or electron= ically stored copies). --=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 .