Smoke Damper 230v actuators

So, regarding 230v actuators, would you terminate it in a switched fused spur or an unswitched fused spur?  

  • This is 'machinery' as defined in the Supply of Machinery (Safety) Regulations. It's also possibly subject to "safety services" requirements. Regardless, it's also subject to CDM Regulations, and Electricity at Work Regulations, for installation, commissioning, maintenance and decommissioning.

    What does the manufacturer, and/or the overall design of the system, recommend? What does the CDM Risk Assessment say?

    From BS 7671 perspective, in installations with certain earthing arrangements, a fuse (provided it could be locked off if required by EAWR) might do the trick ... but there are other factors at play here.

  • Manufacturers don't define this they just stated a 230v supply.  

    So the question is switched fused or unswitched fused on the Damper actuator?  Key pieces of kit from a fire integrity point of view, but I understand the importance of maintenance and ease of isolation. 

  • we would typicall specify  a keyswitched fused connection unit.....

    To ensure we have local isolation but can't be accidentally turned off and can only be operated by the correct personal  

  • Does the manufacturer specify a fuse? 

  • No

  • What on all dampers ? 

  • For me, it would be unfused. I would choose less overload and fault current protection. This is due to the risk of unexpected disconnection of the circuit, as stated in regulation 433.3.3 (v) and regulation 434.3

  • So the question is switched fused or unswitched fused on the Damper actuator?  Key pieces of kit from a fire integrity point of view, but I understand the importance of maintenance and ease of isolation. 

    Interesting ... I would request the information per BS EN IEC 60204-1 Clause 7.2.2, which says:

    The supplier of the electrical equipment shall state in the installation documents the data necessary for conductor dimensioning (including the maximum cross-sectional area of the supply conductor that can be connected to the terminals of the electrical equipment) and for selecting the overcurrent protective device (see 7.2.10 and 17).

    Having said that ... are you the designer of the "system" ... i.e. the larger "machinery" ... if so, then your risk assessments will tell you what is necessary?

    There are specific legislative requirements for the supply of machinery and equipment for use at work or in a workplace.

  • 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! 

  • it is hard to say without knowing more about the design, i think   summarises pefect below IMO.