In reply to a post by ste__:

Thanks, can I ask the reason for this in terms specifically of the inside/out fibre cable? Looking at the specs it appears there is no gel but a waterproof inner membrane. What is the risk of having a long length of this cable in the wall without the outer sheath being removed?

Presumably governed by LS0H building regs etc ?

In reply to a post by ste__:

Thanks, can I ask the reason for this in terms specifically of the inside/out fibre cable? Looking at the specs it appears there is no gel but a waterproof inner membrane. What is the risk of having a long length of this cable in the wall without the outer sheath being removed?

As a homeowner you’re free to run whatever you like within your own home, but BT/Openreach operating across millions of premises, are really bound to comply with wider building regs and controls which don’t look kindly at running external grade cabling in internal spaces due to smoke, and hazardous emissions should there be a building fire. There’s a heightened sensitivity of fire safety in building control since Grenfell.

Personally I just find external cable much stiffer and harder to work internally. Gels etc are messy and get everywhere.

The risk is probably quite low in a single dwelling, but on a larger commercial and residential MDU and especially within ‘plenums’ (air handling spaces) there could be a more significant risk especially with large numbers of cables etc. The type of sheath (PVC, low smoke zero halogen) and the presence of water blocking gels which could be flammable or give off toxic gases etc when heated or burnt etc is covered in various building control regs.

In reply to a post by ste__:

Thanks, can I ask the reason for this in terms specifically of the inside/out fibre cable? Looking at the specs it appears there is no gel but a waterproof inner membrane. What is the risk of having a long length of this cable in the wall without the outer sheath being removed?

The outer sheath on many external cables emits poisonous fumes when burned and isn't suitable for indoor use.

That's likely the case with the inside out cable. It's not just for aesthetics.

Edited by j0hn83 (Tue 22-Mar-22 19:26:29)