The circuit is protected with a GFCI in the main breaker box. We did=20
have problems with nearby (not close) lightning strikes opening the=20
GFCI. The GFCI was 30 years old, installed when the house was new.=20
Replaced the GFCI 2 years ago, no problems since. Maybe no lightning=20
strike close enough. :)  The PIC > Fiber Optic > B&B Electronics=20
convertor > 2 wire RD-485 in house basement > TRI-PLC PLC  has been=20
flawless.  :) :) I better knock on some good wood. :)

On 1/30/2012 12:33 PM, Isaac Marino Bavaresco wrote:
> Beware, stray ground currents and lightning strikes may be an issue.
>
>
> Isaac
>
>
> Em 30/1/2012 14:21, Steve Willoughby escreveu:
>   =20
>> On 30-Jan-12 05:50, Carl Denk wrote:
>>     =20
>>> I have 200' to a natural gas well with one 3/4" conduit for heating the
>>> enclosure. I wanted to add communications to a PIC for pressure and
>>> temperature readings. It was felt to run any communications wired cable
>>> in the same conduit would result in crosstalk and garbage messages. I
>>> settled on 62.5/125 um fibe optic which has been working great for 6
>>> years. Today I probably would do it with X-10.
>>>
>>> This is an overkill for the application below, but running signal and
>>> power close together is a concern and needs investigation before
>>> committing to the work. Have you considered X-10 and it's successors?
>>> Checkout Smarthome.com
>>>       =20
>> Even here, I think X10 wouldn't be practical since these aren't powered
>> by mains current.  Each of the bricks is an 8-pin PIC driving a few
>> high-brightness LEDs which light fiber optics to the surface, powered by
>> 5V DC.  I think crosstalk is less of an issue with DC power, but there
>> is the issue of stray RF interference, although having the cables
>> underground may help (still need to look into that).
>>
>>     =20
>>> On 1/30/2012 4:55 AM, Mike Harrison wrote:
>>>       =20
>>>> In a situation like this, where you don't have noise or long-distance =
issues, probably your main
>>>> risk is problems caused by the shift in the level of the ground caused=
 by the power draw of the
>>>> lighting.
>>>> Another potential risk is damage caused by shorts from your supply dur=
ing installation - RS485
>>>> transceivers will typically take 12V without damage.
>>>> A 75176  RS485 transceiver is not exactly expensve
>>>>         =20
>> True, although the main cost I'm concerned about is PCB real estate--I'm
>> trying to make these things as tiny and trouble-free as possible, since
>> most likely they'll end up buried permanently in the walkway, with just
>> a DC power connection and RS485 line from the house to the first brick.
>>    The question is whether to keep the RS485 going from brick to brick o=
r
>> switch to something simpler at that point.  Might be just as well to
>> spec in a bunch of 75176s anyway.
>>
>>
>>     =20
>   =20
--=20
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