After initially thinking I wanted a fibre optic network link, I’d mostly settled on using a copper Cat 5E Ethernet link between the House and the Outbuildings, to connect their separate computer networks together. The reasons for favouring a copper Ethernet link were:

• I happen to have about 150m of Ubiquiti outdoor grade Cat 5E Ethernet cable going spare, from when I bought a 305m reel to install outdoor cabling for the CCTV cameras that monitored the site and the construction of the House 10 years ago – so this enables the buildings to be linked ‘for free’
• This network link will directly-connect the network Routers¹ in each building, which (currently) only offer 1Gbit/s copper Ethernet ports and so would need Media Converters to connect over a fibre link
  • When these Routers need to be replaced, I would expect to purchase devices which have SFP+ ports which would take an SPF+ module to enable a fibre cable to be connected directly to each Router and synchronise at 10Gbit/s
  • Media Converters aren’t especially expensive – roughly £25 each – but need mounting somewhere and need their own power supply
• The physical cable route between the two Routers takes ‘the long way round’ but is less than 100m, so the Cat 5E cable should enable a 1000BASE-T connection, at 1Gbit/s
• 1Gbit/s will be plenty of bandwidth, given the planned use of the Outbuildings

However, I have just installed 85m of outdoor grade 8-core bulk fibre cable, because:

• I had to install another cable along the same route, to extend a Current Transformer clamp connection to enable the Tesla PowerWall 3² to monitor the existing AC-connected solar PV inverter’s generation output
  • About 1/3 of the cable run is through the now-fully-insulated loft space above the Workshop, so it’s quite a difficult job to balance on the roof trusses (while unable to stand upright) and attach the cable to the cable baskets using the existing releasable cable ties – and it’s no harder to do that for 2 cables than for 1
• Unterminated bulk fibre cable is surprisingly cheap – less than 50p per metre – so it’s not a major problem if the fibre doesn’t get used for a while – or ever

I’m still planning to use the copper Cat 5E initially, so I won’t pay to have the fibre spliced to pre-terminated ‘pigtails’ until I see how that performs (or doesn’t). If the Cat 5E works OK I’ll wait until I upgrade the Routers to light up the fibre link.

I selected Single Mode (OS2) fibre, with an outdoor-grade PE sheath (since about 25m of the run is in an underground duct between the buildings) and 8-core because it was only fractionally more expensive than 4-core.

Initially I found the many variants of fibre types and connectors quite confusing but this forum post by an amateur astronomer, in relation to network-connecting an observatory. proved very helpful in cutting through the jargon and homing in on the right solution – although they advocate using pre-terminated fibre which can be difficult to install when there’s not much space available in an existing duct.

1. I’m using the term “Router” in the strict sense of its computer networking definition: a device that provides OSI Layer 3 connectivity, routing TCP/IP packets between Layer 2 network segments ↩︎
2. Strictly speaking it’s the Tesla Backup Gateway 2 which does the monitoring – and then passes the measurement to the PowerWall 3 ↩︎

Fibre Connection Between the House and the Outbuildings by Marsh Flatts Farm Self Build Diary is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.