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Local Isolation For A/C Internal Units

Sparkymania
Hi

Doing EICRs, and the remedials resulting from them.


An issue had been raging as to whether an internal unit needs to have a local isolator.

There have been 2 schools of thought over this issue with others I am working with.


First one:

It is a an electromechanical piece of equipment and needs a local isolator even though it is being fed by an external unit that has it's own isolation.

Second one:

It is fed by the external unit and they are both one piece of equipment even though they are split with the two parts in different places. Turning off the isolator to the external unit isolates all the equipment.


In my opinion a local isolator is still needed as there is no way of knowing if the internal unit is definitely part the the external unit being isolated. It may just be off at the controls.


I have come across many A/C units that have been installed by A/C engineers and they have not put an isolator on the internal unit. I'm wondering if there is a reason that they don't or if it's just ignorance of the regs on their part. I would have thought their training would have included that. Is there something that they know that means they don't need to install an isolator to the internal unit?


Anyone have any thoughts?


Thanks

  • 0
    The motor section 5.1.1 (d)  does suggest local isolotor.


    In the next pic 462.3 It gives located adjacent to associated equipment as an option, not a requirement.
  • 0

    Sparkingchip:

    Three examples from domestic installations.



    • Where a hot water cylinder with an immersion heater is in an airing cupboard upstairs and its radial circuit is supplied from a dedicated MCB, although there may be a double pole control switch in the kitchen I still install a local double pole switch adjacent to the cylinder in the airing cupboard.

    • A PIR operated LED flood light mounted on an exterior wall can be wired directly into a lighting circuit supplied by a MCB without a local isolator or control switch.

    • Where there is a central heating boiler in a kitchen supplied from a SFCU in a airing cupboard that is elsewhere in the house I generally fit a three pole switch to isolate the boiler adjacent to it. But when the boiler is supplied by SFCU adjacent to it in the kitchen I don’t install any isolators for the central heating system equipment in the airing cupboard.


     Andy Betteridge 

     




     

    464.2 Suitable means shall be provided to prevent electrically powered equipment from inadvertently or unintentionally reactivating during mechanical maintenance, unless the means of switching off is continuously under the control of any person performing such maintenance.


    That gives you a couple of choices.


     Andy Betteridge
  • 0
    Exactly the same as what I would do. But that's doing an installation.

    However, if there's no local switch adjacent to the hot water cylinder how would you deal with this on an EICR? If the double pole switch in the kitchen cannot be locked off it is not suitable for isolation. However the MCB is. Reg 537.3.2.2.

    In that case it's compliant.

  • 0

    You can't test live first, then isolate, then test dead.



    Why not? It might involve some extra walking, but isn't that exactly the normal procedure?


    The motor section 5.1.1 (d)  does suggest local isolotor.



    For an EICR you need to be referring to the regs proper. The bit at the end of 462.2 might be relevant - "Provision may be made for isolating a group of circuits by a common means, if the service conditions allow this" - i.e. where acceptable to the customer you could use the installation's main switch and isolate everything - installation, circuit and appliance - all in one go.

       - Andy.
  • 0
    Quite, however I the real world how many plumbers and gas fitters carry a MCB lock off kit?


    Some years ago I installed a central heating boiler circuit with a B3 MCB in the consumer unit and a double pole switch next to the boiler, the British Gas guy who came to service the boiler was a bit sniffy because he said there had to be a SFCU so he could take the fuse out and put a cable tie through the fuse holder with a sign attached to it.


    The consumer unit, boiler and double pole switch were all within two metres of each other in the garage, so with the MCB being lockable and every thing be in close proximity it complied on all counts.


    Andy Betteridge
  • 0
    Ajjewsbury

    You misunderstood what I meant.

    That is exactly the way I would do it to make sure I was operating the correct device for isolation.

    What I was saying was that if a series of machines were already isolated and locked off at remote isolators then the one you was working on would already be dead. In that case you couldn't test live first, isolate then test dead to confirm. Re-read what I wrote. Having an isolator local to the machine you would be confident that you have isolated the machine being worked on.


    Regarding the second bit you commented on. Yeah! If you want to be hung, draw and quartered. Were talking labs, workshops etc. You can't go turning off other equipment just to work on one.
  • 0

    Sparkingchip:

    Quite, however I the real world how many plumbers and gas fitters carry a MCB lock off kit?


    Some years ago I installed a central heating boiler circuit with a B3 MCB in the consumer unit and a double pole switch next to the boiler, the British Gas guy who came to service the boiler was a bit sniffy because he said there had to be a SFCU so he could take the fuse out and put a cable tie through the fuse holder with a sign attached to it.


    The consumer unit, boiler and double pole switch were all within two metres of each other in the garage, so with the MCB being lockable and every thing be in close proximity it complied on all counts.


    Andy Betteridge 




    I totally agree. I install isolators, SFCUs etc next to everything. However, the regs don't require it to be local. I always think of everybody who will be involved in the future. As far as I'm concerned it is both safer and gives the person working on the equipment confidence that it's isolated. Unfortunately, the regs don't require it and therefore this issue with reporting it in an EICR.

  • 0
    I worked alongside a Polish electrician on a job last year, he said “WTF is it that British electricians have about SFCUs”?


    Andy Betteridge
  • 0
    Yes us and them we are poles apart!

    If you think it is safer or just more convenient to have a local isolator adjacent to a boiler or whatever then fine.

    Likewise if Corgi or Gase Safe or "our firm" or "your firm" think so then fine.

    But an EICR is soley dependant on BS7671 and is only interested in the BS7671 position on that particular install therefore SAT/UNSAT and possible coding is within the BS7671 position only. Another bit of paper must be used for any made up rules you`ve agreed with whoever you agreed it with.

    If you want to scribble on the bottom of the BS7671 EICR "* oh by the way, there`s another bit of paper listing some irrelevant bit of tittle tattle we`ve agreed with you atthe same time" well all well and good just so long as they are not listed as BS7671 departures
  • 0
    I worked for an Air-Con company for 3 years. The only time we installed any isolator switches near the indoor unit was if there was a drain pump installed. I always interpreted it as one complete appliance. If it has an external isolator, which is where the feed comes in, then that's perfectly adequate for me, even from a servicing point of view. Even if the indoor unit is not running there will still be voltage at it, so its quite easy to work out if you've turned it off or not. Depends how far you go with testing. If your testing a massive factory installation you test to the panel isolator don't you? Is your client going to pay you to visually inspect all the components connected to it to see if every little heater element or component has an isolator? Most massive factory plant installations would probably fail this.

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