Data cables in thermal insulation

The same considerations apply as to a power cable in insulation - namely that the removal of heat is restricted. However, with the possible exception of power over Ethernet, none of the things you have listed are likely to require the cable to dissipate significant heat, as the signal currents are very small,.  Ethernet for example is a maximum of +/- 2.5V into 50 ohms, about 50mA (0.05A).  Most fire alarm systems are a few tens of mA depending how many points are connected, except when sounding, and at that point things are probably getting warm out side th4e insulation as well anyway.

From a regs point of view, so long as you take the influence of the insulation into account, and are happy the cable will not be damaged by it, it's fine.

Mike.

I am not aware of any such regulation that specifically prohibits this, and in general the absence of prohibition implies permission.

In the vast majority of cases such cables carry minute currents and will not be vulnerable to heat damage if installed within insulation. My only concern would be if numerous data cables bundled together are used for power over ethernet or POE.

In such a situation I would want to estimate the heat production, probably negligible, but needs checking rather than just hoping for the best.

broadgage said:

in general the absence of prohibition implies permission

I wouldn't interpret it like that.

The absence of a particular aspect in a standard might still have to pass the test the test of whether an hazard were reasonably foreseeable but usually most of the reasonably foreseeable issues are addressed in a standard.

There have been cases where the HSE issue notices of a particular instance, where new considerations are to be taken into account before standards and guidance is updated.

Also depends on the type of thermal insulation. You wouldn't want to bury any pvc cables in expanded polystyrene due to plasticiser migration.