Hi !

I'm asked about a network that could be up to 1.2km long. There is no PoE or fancy thing going on, just pure ethernet. The cable should be cat 5e. I have no idea about the max distance between two network devices in this project yet, but I know the common limit is 100m.

The guys designing the network are not experts (I'm not neither), so I'm getting prepared to find more than 100m between two devices in the network.

Is there something dedicated to this task in the mikrotik catalog ? Like ethernet extenders or something like that ? If not what do you use to resolve this kind of problem ?

Thanks !

I would go for fiber, I know there are also copper-based solutions like VDSL extenders but then your bandwith is limited and the risk of lightning damage is very high.

That is correct, for such distances fiber is the best option as it provides isolation to high voltages e.g. in case of a nearby lightning strike.
Fiber SFPs are very cheap today. Plan for the required number of SFP slots when selecting your router/switch. MikroTik has lots of options.

Hi thanks for your answers

I'm not involved in the decision making for this project so I don't think I can influence somebody but I'll give it a try. Moreover, this is not a network for computers, this is for HVAC devices so I don't think they would accept a fiber there.

Any other thoughts on my original question ?

Thanks again

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How is MikroTik involved? Do you use MikroTik swiches or routers? If so, there are many models that have SFP slots and
you can use that to interface between fiber and RJ45 ethernet.
You can place a switch or router at every location to do the conversion.
It will certainly be a more professional solution than trying to use CAT 5E at its limits for ethernet or to use extender modules.
Every installer will confirm that.

If the HVAC units are clustered, with several within 100m, you can use fiber from central location to the cluster and go ether from there.

fibre is certainly the way to go, if you wish to have reliable connection.
point to point wireless link is another option but if you, or your management, is already prepared to run cable, use fibre.
however if data packet is small, LoRaWAN is a good option too. It is low frequency radio stations and receivers that goes for miles and miles. it is designed for sensors and IoT.
https://www.thethingsnetwork.org/docs/lorawan/

We are building a LoRaWAN network where each radio station is connected to the internet by Mikrotik SXT LTE

Besides the lightning, I'll add that copper between buildings can fall victim to ground potential differentials where the copper becomes a current-carrying electrical path for unequal ground voltage. It's not a good idea without real electrical engineering involved.

Fiber is definitely the way to go.

Besides the lightning, I'll add that copper between buildings can fall victim to ground potential differentials where the copper becomes a current-carrying electrical path for unequal ground voltage.

That cannot happen with ethernet, it is isolated from the equipment using a transformer. The exception would be shielded cable with both ends firmly connected to the ground, not a good idea anyway.

Hi,

Mikrotik is involved because I like Mikrotik products

Thanks for all your answers ! Duty noted !

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since no one though of wireless. did you tink of going wireless?

Besides the lightning, I'll add that copper between buildings can fall victim to ground potential differentials where the copper becomes a current-carrying electrical path for unequal ground voltage.

That cannot happen with ethernet, it is isolated from the equipment using a transformer. The exception would be shielded cable with both ends firmly connected to the ground, not a good idea anyway.

True, ethernet hardware is electrically isolated by design, but at the scale of the SMD parts, and I'm just guessing here, I bet a voltage differential of 50-100VAC might jump the gaps and fry it all.

I simply assumed running cable outdoors would naturally use shielded cable, since without the shield the next storm with any nearby lightning is likely to induce enough current to fry whatever electronics are attached anyway.

True fiber is much safer in the case of lightning and other voltage surges, but the originally claimed problem of ground voltage differential due to loading is not a problem for ethernet.
It should be able to withstand 1500V RMS or 2250 V DC.
(not with the el-cheapo-PoE solution found in older MikroTik and Ubiquiti equipment of course)

True fiber is much safer in the case of lightning and other voltage surges, but the originally claimed problem of ground voltage differential due to loading is not a problem for ethernet.
It should be able to withstand 1500V RMS or 2250 V DC.
(not with the el-cheapo-PoE solution found in older MikroTik and Ubiquiti equipment of course)

Are you referring to ethernet or UTP/STP cable?

True fiber is much safer in the case of lightning and other voltage surges, but the originally claimed problem of ground voltage differential due to loading is not a problem for ethernet.
It should be able to withstand 1500V RMS or 2250 V DC.
(not with the el-cheapo-PoE solution found in older MikroTik and Ubiquiti equipment of course)

I was not aware ethernet specs required such isolation. That' pretty impressive considering the microsizes of electronics today. I stand corrected. With UTP ground voltage differentials wouldn't (had better not!) matter with such isolation. STP on the other hand could melt at much lower voltages due to ground differential.