Connecting two homes via Ethernet

[Titan_Master]

Hi,

I am looking for any information as it relates to NEC / NFPA codes which address connecting two homes together via Ethernet cable.

More specifically where it calls out doing so is not allowed.

This question seems to come up a lot but I’ve never seen anyone cite the section in the code where it prohibits the same. Hoping any information the forum members can provide which address this issue about the pitfalls of doing so.

A perfect example of discussion I see all the time on the Internet forums is there are two homes. Obviously each have their own grounding system in place. The goal is to connect house 1 network switch to house 2’s network switch via a 10-250 plus run.

If we just assume the correct cable and install depth is in place. The risk I see is the voltage potential (difference) from one homes grounding system which connect / power the two separate network switches.

We haven’t even addressed the dangers from induced voltage from lightning.

Thank You!

Chase

 

[LarryFine]

Welcome to the forum.

I believe it's neither addressed nor a concern. Ethernet is basically isolated from ground.

 

[curt swartz]

The best solution is run fiber.

 

[Titan_Master]

The best solution is run fiber.

I absolutely agree and this is what’s done in our projects. All the benefits of fibre such as longer distances and immunity from RFI / EMI / EMF posed by lightning, never mind much higher bandwidth capability.

I’ve looked over the NEC, CEC, NFPA, and haven’t seen anything that directly addresses this topic or issues that may arise.

If anyone finds something that relates to codes / correct installation about this ongoing question please do share!

I thank you all!

 

[zbang]

Twisted pair Ethernet is galvanically isolated by design (tiny little transformers at each end) so grounding is not a concern (thus, it's not mentioned). OTOH lightning is a concern, as is the 100m limit. so fiber between buildings has been preferred for decades (and when you cost it out, fiber usually doesn't cost much more than copper).

 

[Titan_Master]

Twisted pair Ethernet is galvanically isolated by design (tiny little transformers at each end) so grounding is not a concern (thus, it's not mentioned). OTOH lightning is a concern, as is the 100m limit. so fiber between buildings has been preferred for decades (and when you cost it out, fiber usually doesn't cost much more than copper).

I agree lightning is a concern and if I was asked to do this with out fibre in the equation. I would install the direct burial (gell filled) shielded cable at the required depth in none metallic conduit.

One end of the shielded drain wire would be grounded at the (head end). Both Ethernet connections would be connected to a properly cUL / UL SPD that is so rated and connected to the single point grounding system within the home.

That would be the most basic I would do to reduce or mitigate induced voltage from lightning.

Thoughts?

 

[tom baker]

Fiber cables are available pre terminated with pulling heads installed. For short distances, say 1 km or less multi mode fiber is less expensive as it uses LED transceivers. There are code requirements for outside fiber entering a building that relate to outside cable not being UL listed.
Another option that is common is to use line of sight Ethernet radios from Ubiquity. Those involve a mast and some grounding.
The code issues are with the fire ratings and routing of comm cables, and some grounding and bonding of wireless is used, types of cables in a building.

 

[tom baker]

I agree lightning is a concern and if I was asked to do this with out fibre in the equation. I would install the direct burial (gell filled) shielded cable at the required depth in none metallic conduit.

One end of the shielded drain wire would be grounded at the (head end). Both Ethernet connections would be connected to a properly cUL / UL SPD that is so rated and connected to the single point grounding system within the home.

That would be the most basic I would do to reduce or mitigate induced voltage from lightning.

Thoughts?

Fiber is immune from lightning and if you have conduit just get preterminated cable.
Fiber is future proof where the bandwidth of twisted pair is limited. The fiber transceivers are plug and play.

 

[don_resqcapt19]

You will need to apply the requirements cited in 725.141.

 

[Fred B]

What if the Ethernet is providing PoE? Make any difference? Would the conditions that not more than 1 feeder or branch be shared between structures be applicable?

 

[Titan_Master]

You will need to apply the requirements cited in 725.141.

This is the section I’ve been looking at over and over through out the years. Unfortunately it doesn’t call out that you *Can’t* connect two buildings that have separate grounding systems via Ethernet.

It also doesn’t call out the use of shielded cable or the real need to deploy a SPD on both ends?!?

 

[hbiss]

What if the Ethernet is providing PoE?

Depending on the distance, PoE could be carried by the cable or it might have to be inserted at the far end. Obviously with fiber it would have to be inserted where the fiber transitions to copper at the far end.

Would the conditions that not more than 1 feeder or branch be shared between structures be applicable?

What conditions?

-Hal

 

[hbiss]

This is the section I’ve been looking at over and over through out the years. Unfortunately it doesn’t call out that you *Can’t* connect two buildings that have separate grounding systems via Ethernet.

Because you can. And how many times will you find two separate buildings with the same grounding systems anyway.

Point is though, that if you aren't using fiber in this day and age for providing a data connection between two or more buildings, either aerially or buried, you are behind the times.

It also doesn’t call out the use of shielded cable or the real need to deploy a SPD on both ends?!?

Why would you use shielded cable?

As for SPD's, Article 725.141 sends you to Article 800 for that requirement. (It's always been my opinion that Article 800 should be the article that governs ethernet wiring anyway.)

-Hal

 

[Titan_Master]

Because you can. And how many times will you find two separate buildings with the same grounding systems anyway.

Point is though, that if you aren't using fiber in this day and age for providing a data connection between two or more buildings, either aerially or buried, you are behind the times.


Why would you use shielded cable?

As for SPD's, Article 725.141 sends you to Article 800 for that requirement. (It's always been my opinion that Article 800 should be the article that governs ethernet wiring anyway.)

-Hal

Because shielded cable was designed for the sole purpose to reduce / mitigate the affects of induced RFI, EMI, EMF over the air.

A properly installed single point grounded cable will offer higher protection when an induced voltage rise (spike) is presented.

Also because that induced voltage will be shunted to Earth ground, via the drain wire. Coupled with the shielded sheath will reduce all of the above RF / EM that is present.

 

[petersonra]

Article 800 clearly only applies to utility type wiring entering a building. It says that.

These are neither feeders or branch circuits. They are class 2 circuits formerly governed by article 725, now moved to a different article number.

 

[don_resqcapt19]

This is the section I’ve been looking at over and over through out the years. Unfortunately it doesn’t call out that you *Can’t* connect two buildings that have separate grounding systems via Ethernet.

It also doesn’t call out the use of shielded cable or the real need to deploy a SPD on both ends?!?

I think if you read all of the rules it will only require a "protector" at both ends.

 

[don_resqcapt19]

Article 800 clearly only applies to utility type wiring entering a building. It says that.

These are neither feeders or branch circuits. They are class 2 circuits formerly governed by article 725, now moved to a different article number.

Actually based on a change in the definition of communications circuit in the 2023 code, these conductors are covered by the rules in 800 and 805 in the 2023 code.

 

[Fred B]

What conditions?

225.30 building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit.
225.3 implies class 2 and 3 in 725, can be impacted by the requirements of 225 and visa versa
Thus the question. Just asking if any situation would be implicated for condition to be in violation by a PoE? Or would condition 225.30(E) exempt PoE?

 

[don_resqcapt19]

225.30 building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit.
225.3 implies class 2 and 3 in 725, can be impacted by the requirements of 225 and visa versa
Thus the question. Just asking if any situation would be implicated for condition to be in violation by a PoE? Or would condition 225.30(E) exempt PoE?

POE is not a feeder or a branch circuit and 225 only applies to feeders and branch circuits.

 

[hbiss]

Article 800 clearly only applies to utility type wiring entering a building. It says that.

I know, we've been down that road before.

I just believe it should be changed to cover data wiring which is what 800 is about- Communications Systems.

725 is about Class 1, Class 2, and Class 3 Remote Control, Signaling, and Power-Limited Circuits. Ethernet doesn't belong there other than the PoE part of it.

225.30 building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit.
225.3 implies class 2 and 3 in 725, can be impacted by the requirements of 225 and visa versa
Thus the question. Just asking if any situation would be implicated for condition to be in violation by a PoE? Or would condition 225.30(E) exempt PoE?

Tell me how 225 applies to communications wiring or LV wiring?? Further, 725 and 800 on are not subject to the articles before them unless there is a specific reference back to the prior article.

-Hal