Gas Block Cover

Gas Block Cover (the bit on the outside of your wall)

All the grey plastic bit on the outside of the house does is to hide the gas-block. All the gas block does is make an air-tight seal to stop any gases entering the house. (just mutter 'building regulations' to the householder, that'll do for explanation) It provides a neat curve for the duct to enter the house horizontally.

At the gas block the black 7 mm changes to white 5 mm which goes through the wall The white duct is special stuff to stop the transmission of fire through the wall. (just mutter 'building regulations' to the householder, that'll do for explanation)

The gas block cover doesn't need to be waterproof. (It doesn't have to be in that usual vertical position, it can be sideways or even upside-down)

Once fibre is installed the gas block cover need never be touched again. It’s worth inspecting to check that the hole through to the house is sealed well. It can be painted, and to be honest grey doesn't look too nice.

It can be anywhere on the outside wall. It can be in your loft.

A 1 metre drill bit is often what you need with thick house walls. We had one that we lent out.

Drill from in to out as it may take a few attempts at different angles and where you exit may be uncertain.

Always thread the cable ties through before you screw it on the wall.

A gas block cover in a typical location.

The joint at the bottom to the black duct is on a bend. It shouldn't be. This is a place where the fibre can stick. At least it is still easily accessible if there is a problem.

Rather than finding someone has concreted it in...

The final fitting looks perfect.

When the fibre is through to the house, the gas block connector is tightened up before the cover goes on.

The whole point of the block is that it should be tightened

It is very easy to forget this

A common location is in some sort of thorn bush

Remember a ladder may be needed for some jobs

Avoid window frames

Via the frame is not popular with B4RN

B4RN dislike this kind of fitting because you are a bit stuck when you want to replace the window frame. (Actually this particular frame looks as though it will last many decades, and you can if necessary pay for a new fibre blow)

The main thing wrong with it is that it looks horrible. And they may have trouble with this particular one when the double-glazing needs replacing, if only because the double glazing man will just unscrew the gas-block cover and just pull it away while he puts the glass in.

I think we caught the bloke who goes through the window frames.

Bringing your black duct into an outhouse or through your loft sometimes means that a gas-block cover is not necessary.

The white duct has a complicated route through the wall, which is okay in principle, but as the grey case was tightened up it kinked the duct and the fibre couldn't get through. A case where the B4RN man or the volunteer has to spend time sorting it out themselves.

A lot of the grey cases seem to have big gaps behind them. You assume someone tidies these up after you have been ?

Co-operation with neighbours

It's possible that your duct will have to cross several other people's gardens before it gets to you, and it may even have to be routed along someone else's gutter or roof.

If you imagine a block of flats under the same ownership then this would be a good way of connecting them up. This is one where you need B4RNs advice, but you can see the idea.

a 12 fibre cable can be blown short distances through 7mm duct. Surface mounted fibre splicing boxes can be mounted on property walls and serve up to 6 properties. It is possible to sling tiny distances between semi detached properties with reinforced black 7mm duct.

(If you can't find a ladder, improvise) But someone is going to have to do some splicing at that box, so think it through before you site it up high.

Metal conduit to neaten up the installation

Stapling the duct crimped the fibre inside and damaged it

A gas block cover does not have to be aligned upwards, necessarily. It often is, because the black duct usually comes up into it from the ground. The gas block cover does nothing but hide the gas-block and give you a nice curve to bend the duct round. It could be 'upside-down' if you ensured a good seal at the wall hole,

This gives you more options. You could have the arrangement there in the left picture rather than the conventional set-up on the right.

Jobs don't always have to be done in a certain order. If you have a team blowing house fibre and you have houses not quite ready, then you can still get the fibre blown. As long as you know where the router back plate will be sited then the right length of fibre can be left in a coil outside.

Here the fibre is already in that 7 mm coil which is just acting as a temporary cover for about 4 metres of fibre. Now that the house blowers have left, the owner can complete the installation. The fibre can be sorted out when the back plate is spliced, or better, by a volunteer who has been shown the simple produce of feeding the fibre through into the house.

Drill through the wall before fitting anything else, then you can line up your gas block cover and your FTU precisely by having the white duct in place.

Check the gas block cover fits well first, it has a small protrusion at the back (which could be cut off with a hacksaw if necessary)

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