I ask this question as you should just have a straightforward answer, but it's never clearly defined. It's expected that Electrical designers should just know what to use. No manufacturer states that level of detail other than power requaitmenta and voltage, i.e 230V. 

Of course, installing a switched fused connection unit (spur) poses the risk that someone forgets to turn it back on or accidentally turns it off, meaning the damper doesn't work in the fire scenario, but then I understand the requirement for local isolation from a maintenance point of view. Let's be right; these dampers are life safety equipment normally installed out of the way where only authorised people can access them, but still, as an industry, what should we be designing too? Switch fused or just fused?  

lyledunn said:

However, either way, I agree with GK's post above. You need to nail the designer. It may well be that whilst you are simply installing the device, you are also the designer, in which case you should take cognisance of 8 (1) of the CDM Regs (quoted NI version of 2016)

That is not a patronising requirement, it is a consideration that I often have to ponder myself when I feel aspects of my competence to specify being stretched on even simple projects.

I'm not disagreeing with the perspective of considering the CDM Regulations, which would apply in terms of safe maintenance in all installations (including domestic), but I think in this case it's likely that Section 6 of the Health & Safety at Work etc. Act 1974, and perhaps also because dampers are often part of a ventilation system, the Supply of Machinery (Safety) Regulations 2008 put duties on BOTH the manufacturer and the installer.

However, I think it also needs to be said that, under CDM, the Client (or at least the appointed Principal Designer CDM Coordinator has a duty to be part of the risk evaluation for this particular issue, and the decision between risks associated with overcurrent protection being omitted, and potentially means of local isolation vs 'life safety system operation' ... it's not a decision for the 'Designer' alone.

MS01 said:

but still, as an industry, what should we be designing too? Switch fused or just fused? 

and I think the above regards it being a decision that has to be reached by the relevant parties under CDM is why there's no "firm industry guidance' ...

gkenyon said:

However, I think it also needs to be said that, under CDM, the Client (or at least the appointed CDM Coordinator) has a duty to be part of the risk evaluation for this particular issue, and the decision between risks associated with overcurrent protection being omitted, and potentially means of local isolation vs 'life safety system operation' ... it's not a decision for the 'Designer' alone.

CDM Coordinator? That specific role no longer exists under CDM 2015 and the duty for such design matters will rest with the Principal Designer who will need to collaborate with others to ensure that, amongst other considerations, the structure and its integral fixed services can be safely maintained.

You might want to consider a neon on any FCU, giving a visual indication that there is power to the circuit.

lyledunn said:

CDM Coordinator?

Apologies, yes, Principal Designer (appointed by the Client). I think I had a timewarp there !

A smoke damper has to operate if the power fails, so if its 230v with no battery back up supply it should be spring or gravity closing to fail "safe". In which case it wouldn't really matter what isolation or fuse protection is installed so long as it can be safely isolated for maintenance.

regards burn

burn said:

A smoke damper has to operate if the power fails, so if its 230v with no battery back up supply it should be spring or gravity closing to fail "safe". In which case it wouldn't really matter what isolation or fuse protection is installed so long as it can be safely isolated for maintenance.

I'm sure that's not always the case ... for example with smoke control or "positive pressurisation" systems, a "fail to close" might be just as bad as "fail to open".

True, but in those cases there would have to be secondary supplies with auto-changeovers to enable the damper to both close and open. From the original description I didn't think that was the case here.

burn

burn said:

From the original description I didn't think that was the case here

I agree that's probably the case, but the original question is rather brief and devoid of context.