I need to run data through single mode fiber (1.5km) to connect to a remote site. I have to cross a road that has a copper data cable run underneath it. (cat5e) The local authority doesn't allow me to run fiber under the road. After the road I need to go back to fiber to run last ~600m. A final conversion will need to go back to copper to the remote location. The first copper to fiber is through a switch. I envision ip67 media convertors after that mounted in pedestals above ground. (connections 2 and 3, I have AC power on both sides) the final remote site would be another switch. Can I convert data multiple times in a single run to achieve this? Is there a limit to the number of conversions between copper to fiber in a single mode run?
1
-
Modern media converters are switches. So, technically there's no limit, but there are practical limits. Every hop is a point a frame could silently disappear. Unmanaged switches have no means of communicating errors.– RickyCommented Feb 12 at 17:54
Add a comment
|
1 Answer
No, on a modern full duplex network there is no specific limit to this sort of thing (half duplex Ethernet did have limits on the number of repeaters between switches, but half duplex is a thing of the past).
Putting active equipment in outside cabinets is less than ideal, but sometimes you've got to do what you've got to do.
Also normal Cat5e is not rated for running underground. If this is an existing cable, the first thing I'd want to do is test if it actually works. If it's a new cable then make sure appropriately rated cable is used.
While you say you have power on both sides, I would strongly consider powering one of the media converters over POE. While copper Ethernet does have some level of electrical isolation, it is still better not to run copper Ethernet connections between equipment powered from different electrical systems where possible.
-
The ANSI CAT specs are for the signal capabilities, they say nothing about the environment of the cable. There ARE outdoor rated, direct burial CAT rated cables. That said, Cat5e is only rated to 1G. A short enough span might handle 10G, but you're beyond what it's designed for.– RickyCommented Feb 12 at 17:47
-
As for electrical isolation, common media converters are DC powered - 12v wall-wart. So it would not necessarily be an issue having them on different branches, or phases. In fact, it would be rather trivial to run them entirely off-grid. ('tho they would be a target for theft.)– RickyCommented Feb 12 at 17:49
-
My undestanding is that lightning storms can often create potential differences that will overwhelm the isolation barriers in normal electrical equipment. So it's best not to run copper data cabling between equipment fed from different power systems (different phases of the same system is fine). Commented Feb 12 at 18:12
-
You're talking about ground potentials. Ethernet electrical signals are not reference to ground. As the media converter is DC powered, it isn't necessarily linked to ground either -- the common two prong wallwart wouldn't be grounded, but a metal box in the ground would be. If lightning hits anywhere near this setup, it's likely to fry both sides... when the 120v becomes way more than 120v. Shielded cat5e would be a different matter, as the ends could be at different potentials. But where is it grounded? We're talking about a 30ft span under a road?– RickyCommented Feb 12 at 18:26
-
It is indeed shielded direct burial cable, the casing is marked cat5e. It was installed in 2022, but is from a spool 15 years old. (new old stock) We had it left over from another job. I planned on lightening blowing out both units, but as a precaution, I'd use ground fault isolators (properly grounded) to handle some surges. The road crossing length is ~120'. The cable is 8ft underground, but rises to 12" underground on each side. I have an quality direct burial 14/2 running across the road as well. (therefore the power would be from same source-re grounding) Commented Feb 12 at 20:39