How to protect signal and control cable from lightning ?

Thread Starter

meowsoft

Joined Feb 27, 2021
367
How is best method to protect outdoor signal from lightning ?

Signal and control cable is use to control smart home security sensor; LDR sensor, flame sensor, PIR sensor, also control 5v Relay, 12v DC Solenoid valve , etc
I use CAT5e wire for this wire, can I use ethernet surge protector to protect that signal and control cable from lightning risk ?, is that good idea ?, can ethernet surge protector interference sensor signal (some is PWM) ?, and do you think that ethernet surge protector can change voltage inside signal wire ?

also how to protect 5v 16channel arduino relay from voltage spikes ?, let's say if relay get failed, and 220v come into 5v control cable, it can damage micro-controller, power supply, and another stuff than connected both directly and indirectly, can I use ethernet surge protector to protect 220v enter 5v DC wire ? I think that stuff is only protect from more than 1kV voltage spike, another good way ?, MOV ? GDT ? TVS ?
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
IMO, the only hope is to set up a separate lightning conductor system if worried about direct lightning strikes on outdoor conductors.
I have seen a few instances where it has hit external co-ax etc and was not pretty.
 

MisterBill2

Joined Jan 23, 2018
8,773
For lightning protection it is not likely that an ethernet protector will help much. For protection against 220 getting into the arduino, using the right type of relays that have adequate spacing between coil connections and contact connections is the best choice. Such relays are quite available but the cheap junk with the close terminal spacing is much more common.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
For lightning protection it is not likely that an ethernet protector will help much. For protection against 220 getting into the arduino, using the right type of relays that have adequate spacing between coil connections and contact connections is the best choice. Such relays are quite available but the cheap junk with the close terminal spacing is much more common.
Yes... But why ethernet protector will not help in my case ?, that protector is mikrotik manufacture, also can protect data center equipment, I think it's not problem, but I use CAT 5e cable for arduino sensor not computer network only use same CAT 5e but it's not network cable and some part's use R-VV cable, but I always connect that cable with RJ45 plug for best mechanical and electrical connection also easy maintanance, my question is that ethernet protector can interference arduino sensor nor another such things ?, and do you think it's protect all 8 cores from voltage spikes ?, normally CAT 5e use 8 cores, and only 2 or 4 for power over ethernet, some ethernet protector only protect that core for PoE, 4 another core isn't protected
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
IMO, the only hope is to set up a separate lightning conductor system if worried about direct lightning strikes on outdoor conductors.
I have seen a few instances where it has hit external co-ax etc and was not pretty.
Yes...
but my sensor is very very complex, for example there is vibration sensor, microphone sensor, flame sensor, IR sensor, PIR sensor, and another sensor that connected to the gate, if gate is vibrated nor noisy sound is detected (example : if someone try to cut padlock) it's send signal to micro-controller, and micro-controller input output signal is monitored by computer server, also computer server make scan and face recognition to the gate surveillance camera, if person is detected, it's can trigger alarms.
problem is : if lightning hit the gate, that sensor can received transient voltage, and can spread to another component's like micro-controller, DC supply system, also computer server and primary AC electricity in office
do you have some idea to solve that problems ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
The typical lightening strike has been estimated at 300 million Volts and about 30,000 Amps. Heck of a job to protect anything that gets in the way ! o_O
Ok... do you have some idea ?, also that computer server connected to table where everyday I am work in my office, if lightning hit the gate, also can spread to DC supply system, and can spread to my table (some metal parts is bonded-grounded with same ground system with DC supply ground and gate bonded wire) ? an then kill myself, do you think that is possible ? also the gate was bounded-grounded with big copper conductor
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
If lightening hits the gate, believe me, everything on it would be fried, in my personal experience of similar events.
Your only hope is that either lightning does not strike it or set up an alternative conductor path that it would prefer to take.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
If lightening hits the gate, believe me, everything on it would be fried, in my personal experience of similar events.
Your only hope is that either lightning does not strike it or set up an alternative conductor path that it would prefer to take.
Ok... how to protect that conductor in the gate to prevent transient voltage travelling into another wire, can I use fuse ? or something ? or ethernet surge protector ? (It was not expensive and easy to use, about 129 wire cores that placed outdoor go inside building, it's not good for make DIY surge protector for that very complex wire), and I can't find surge protector for sensor or electronics signal cable
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
As @MaxHeadRoom indicates, it it really impossible to protect from a direct strike.
But here is an example of protecting an RS485 line.
View attachment 235749
This is from the data sheet published by Morsun for one of their isolated RS485 drivers. It may be a starting place to help in case of close strikes and static build up.
https://www.mornsun-power.com/html/pdf/TD5(3)31S485H-E.html
It's not RS 485, it's arduino sensor cable (PIR, IR, LDR, Microphone sensor, and another such sensors), 5v relay placed outdoor, LED placed outdoor, solenoid water valve placed outdoor, DC water pump placed outdoor and another things, that about 129 cores cable, I use R-VV and CAT5e cable, I was think to use ethernet protector because they have built in surge processor that can also protect equipment with CAT5e cable (usually computer, outdoor router, network equipment, CCTV, and such things), and no commercially available protection devices
 

andrewmm

Joined Feb 25, 2011
1,473
As said above, basically you can not protect a circuit that is hit by lightening,
Luckily, if a circuit is hit by lightening, it tends to vaporise, so it not working is least of your problems,

What you can protect against is a near by lightening strike,

A car is a great example of that,
a car can be hit by lightening, and survive quiet well,
and yes, the car tyres have no effect, its the metal shell that matters.

So screen everything,
metal box's , screen terminating on outside of the box,

Standard screened cable will not take a lightening strike, it will burst into flames,
but a near by strike will be attenuated nicely by the screen.

Now you have a realistic voltage / induced current to cope with,
then you can do things like opto isolating, transformers,
MOVs , traanzorbs , spark gaps et all.

The aim is to have a defined route for the input / output,
away from other signals.

Then you can take it to what level you want.
ethernet isolation with a spark gap is quiet a good compromise.

What you need to do is look at the strike voltage , speed and current any system you make can handle,
and if in doubt, protect in depth,

In general, higher frequency signals are harder to protect than DC ones, as all the protecting devices have some capacitance, which higher speed signals don't like.


You can take it as far as you like, the idea is to take out more and more of the voltage/ current with each stage, till its low enough for your devices to cope with,

Just remember , high voltage spikes are real fast edges, and will take the shortest distance to earth,
if that happens to be across your circuit board, it will do.
 

andrewmm

Joined Feb 25, 2011
1,473
BTW: Ethernet cable tends not to be screened, and if is not very well, use outside Ethernet cable has a triple screen and separate ground drain wire, and connects to a proper round, EMC proof connector, not the RJ45 ones.
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
@meowsoft Your referring to relatively minor disturbances.
When it comes to DIRECT lightning strikes, I reiterate, if you want HV protection, you need to provide that alternative path.
Forget shielded and co-ax cables etc, lightning just evaporates it.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
BTW: Ethernet cable tends not to be screened, and if is not very well, use outside Ethernet cable has a triple screen and separate ground drain wire, and connects to a proper round, EMC proof connector, not the RJ45 ones.
Some use ethernet, some use R-VV cable, not problem with cable but the sensor itself all wire except go to individual sensor is protected with good conduit more better than outdoor cable, about 2.3mm thick PVC pipe, but sensor let's say PIR is attached to the gate, naked without any case, and that wire connected to almost every part of electricity indirectly
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
@meowsoft Your referring to relatively minor distrubances.
When it comes to DIRECT lightning strikes, I reiterate, if you want HV protection, you need to provide that alternative path.
Forget shielded and co-ax cables etc, lightning just evaporates it.
Ok... let's say we attached micro switch to the gate (to detect open close status), and micro switch was attacked by transient voltage (everything not only lightning), how to protect that micro switch wire from transient voltages ?, also micro switch wire is only about AWG 28, and the gate is grounded by about AWG 7 and AWG 5 bare copper, do you think transient voltage will choose AWG 28 than AWG 7 wire ?, and what's happen if AWG 28 wire it's hits by lightning or something transient voltages ? and to prevent transient voltage that enter AWG 28 wire from entering another equipment ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
BTW: Ethernet cable tends not to be screened, and if is not very well, use outside Ethernet cable has a triple screen and separate ground drain wire, and connects to a proper round, EMC proof connector, not the RJ45 ones.
Yes... but it's a good idea to use ethernet protector for not ethernet devices ?, only same cable, let's say I use CAT5e for microswitch wire that attached to the gate, and connected via ethernet protector, it's that good idea ? and can provide adequate protection ?

View attachment 235756Microswitch like in picture, but I use cat 5e cable and RJ45 connector for wiring system, and connected through ethernet surge protector, not even an ethernet devices, only same wire, because cat5e is cheap than AWG 28 or AWG 26 wire, ethernet protector placed between arduino and microswitch sensor attached to the gate
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
Yes... but it's a good idea to use ethernet protector for not ethernet devices ?, only same cable, let's say I use CAT5e for microswitch wire that attached to the gate, and connected via ethernet protector, it's that good idea ? and can provide adequate protection ?

View attachment 235756Microswitch like in picture, but I use cat 5e cable and RJ45 connector for wiring system, and connected through ethernet surge protector, not even an ethernet devices, only same wire, because cat5e is cheap than AWG 28 or AWG 26 wire, ethernet protector placed between arduino and microswitch sensor attached to the gate
This case arduino is connected through ethernet and switch also connected to about 23 arduinos, also switch is connected to all computer in workstation and DC supply is connected to another DC equipments include lighting system and surveillance camera, so.. if lightning enter micro-controller it can make very great damage to thousand of equipments also make personnel hazards
 
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