Does the manufacturer specify a fuse? 

No

No

Then I assume this is just a relatively small assembly where the actuator is installed to the damper body by the manufacturer of the damper. Usually 0.75mm2 connecting cable for 230v on/off and 6-core 0.75 for auxiliary.

Your question is a good one. It is one of those seemingly simple questions that can engender an obstruse response that perplexes and irritates the lads at the coalface. I am not being high-brow or patronizing, for I was a long time at the coalface myself. 

I dont have any idea about the extent of your job, whether it is one damper designed for simple operation or one of many, designed to operate through a complicated cause and effect matrix.

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.

 Just to throw something out there, and in the absence of manufacturers instructions, you may need a fuse, you may not, depends on the CPD of your supply circuit. Most of the actuators on smoke dampers are maintenance free, do not require overload protection and are fitted by the manufacturer to ensure appropriate overall responsibility. 

Isolation? Could be done from a remote single point.

Maintenance? Could be done from a remote single point.

Emergency? Cant think of a reason but could be done from a remote single point.

Functional? Not normally required but would assist in checking operation and could be done from a remote single point.

So I guess you could connect the actuator by whatever method you deemed appropriate, providing you took due account of the individual circumstances, including the likely competence of persons carrying out maintenance, the layout and function of the system, accessibility constraints etc. All of which, the designer should include in an appropriately robust RA before specifying a connection arrangement. 

That took longer than I thought.....going for a cup of tea! 

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.

lyledunn said:

CDM Coordinator?

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