Networking ducts between buildings

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psc

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We're in the final stages of buying a new home, which includes a main house, a large barn+workshop, an annexe, and some other random outbuildings. I've already got a pair of ICX6450 + both SM & MM 10G transceivers, and plan to connect the three main buildings with fibre. All already have power. I'll either add a third switch or service the annexe with 1G from the switch in the main house in the short term.

The three buildings are essentially set on 3 sides of a quad, which is also the (gravel) driveway. I'm planning to run pre-terminated fibre (LC) through underground ducts with a couple of access boxes at corner\junction points. Total distance will be ~40m. Since there's water, electric and heating oil connections under there already, I'll have to play it somewhat by ear, but I'm after any advice you can give. I'm in the UK.

- I'm thinking flexible smoothwall ducting, in roughly straight lines between access boxes. Reasonable?

- I might want to subsequently pull some SWA to change how power is distributed, so I'm thinking 75-100mm diameter black ducting with warning tape over. (2x fibre, 2x copper, 2x 6mm SWA)

- What depth should I aim for?

- Access\inspection\manhole options seem to vary 100-600mm; 200-300mm sounds fine to me as long as it's not too deep, but I might be missing something. Can you easily run ducting into the square boxes at an angle or do I need cylindrical?

- I'll leave in pull cords for each ducting section; what else do I need to think about?
 

Samir

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Not familiar with building codes or soil or materials available in the UK, but it sounds like you're on the right track so far.

I'm assuming you would you be trenching the ducting? What type of loads will the driveway have? Does it have any supporting structure underneath other than the soil?
 

Mishka

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I would run it alongside the driveway so if a large lorry pulls in it wont crush the pipework depth sounds good though, dont need very deep for it just deeper than someone is going to do gardening basically
 

fohdeesha

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not sure about the UK, but in the US that wouldn't pass inspection. NEC forbids low voltage data (the copper you're speaking of I'm assuming is network and not power?) mixed in a conduit with power (your SWA pull)
 
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psc

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I'm assuming you would you be trenching the ducting? What type of loads will the driveway have? Does it have any supporting structure underneath other than the soil?
Yes, I'd be digging down; it sounds like recommended depth varies 250-750mm with what's in the duct (as does the colour) but it's not yet clear to me what's mandatory and what's simply custom & practice; see Cable Pulling Equipment - A Cable Duct Laying Guide From BT Openreach for example. As far as I know there's nothing under the drive except existing utilities, but there's a wastewater treatment plant access hatch off to one side; I highly doubt that extends under the driveway.


I would run it alongside the driveway so if a large lorry pulls in it wont crush the pipework depth sounds good though, dont need very deep for it just deeper than someone is going to do gardening basically
I was hoping I'd be able to go across under the driveway if I was deep enough; I doubt a large lorry would make it down the access road, but still... It might be worth going just for twinwall ducting if that would make it viable; it effectively breaks down as 1.5 'easy' sides of the square going under the driveway vs 2.5 'harder' sides in the other direction.


not sure about the UK, but in the US that wouldn't pass inspection. NEC forbids low voltage data (the copper you're speaking of I'm assuming is network and not power?) mixed in a conduit with power (your SWA pull)
I'll have to check that; I was indeed meaning network. I'll almost certainly have to get proper advice from someone local for legal requirements, structural, etc., but I want to avoid ending up with something that meets the rules but ignores good practice and practicalities! Certainly I'll need a sparky to actually connect up any new SWA and sign off on it, which probably means I'll need someone to sign off on the ducting before it's buried just in case.

Sounds like I might need 2 separate sets of ducting if I want to leave my options open; even if it's not needed now, it might be in a year or two when I get round to shuffling the power distribution. Hopefully one set of access hatches will suffice...
 
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zunder1990

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not sure about the UK, but in the US that wouldn't pass inspection. NEC forbids low voltage data (the copper you're speaking of I'm assuming is network and not power?) mixed in a conduit with power (your SWA pull)
Fohdeesha, "NEC forbids low voltage data" that is mostly not true. You can mix low voltage cable data cable and power cables in the same conduit BUT the low voltage cable MUST have an insulated jacket rated at or above the rating on power cable.

Aproved 600-Volt volt rated power cable and 600 volt rated ethernet
Not approved 600-Volt volt rated power cable and 150 volt rated Thermostat Wire or 300 volt Security-Cable

In the real world you will have a hard time finder fiber/ethernet with a rating of 600 votes so it that regard you will most likely not be able to run them together .
 
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fohdeesha

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it's been a while, but from what I remember with that exception clause (620.36), it only applies if everything else in the conduit being mixed is also classified as Class 1 wiring (power limited control wiring etc). A power feed as he is running would definitely not be class 1, so the 620.36 exception allowing it to be mixed with the proper insulation rating doesn't apply. That said this was probably one of the rules I saw broken the most often, depends on the inspector you get. Some discussion here - Combining circuit types in a conduit
 
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