Local Isolation For A/C Internal Units

Actually this is a I am currently involved with and the circuit supplies most of the ground floor lighting within the house, the gate pillar lights and has the gates themselves hardwired into it with the only point of isolation for the gates being the single pole B6 MCB in the consumer unit.


Good, bad or indifferent?


Andy B.

motorised gates on a lighting circuit? Not reet good in my humble


Whereas, conversely, a power circuit (Ring or Radial) with FCUs feeding 3A/5A lighting (sub?) circuits might be OK

i have just been through the regs as I was thinking of the term "local isolator" and wondered if that term is actually used. Everyone uses it when reporting no "local isolator" for any equipment that you would expect to have one for maintenance. 

However, there is no term "local isolator" or "local isolation" in the regs.


In the context of this post it is under "switching off for mechanical maintenance". Funny thing is there is no "switching off for electrical maintenance" section.

464.2

537.2.4

537.3.2.2

537.3.2.4

Nowhere does it say that this has to be local to the unit.

My company is obsessed with local isolation for everything but I'm now wondering about this being reportable, especially as code 2. (I would report these as code 3 but it would be changed to code 2 when we get the remedials list back).


I think local isolation, a lot of the time, is merely a matter of convenience. For example, a fan isolator in a bathroom. Inconvenient if you have to isolate the whole circuit but not reportable on EICR. 

Admittedly, the A/C unit is different as you can turn of the wrong isolator in a group of external units. If I was working on an internal unit isolated from an external unit I would feel safer if I had local isolation. It's not always obvious what feeds what. I can't count the amount of time I've had to spend on identifying them when testing. Problem is even after that I'm only required to label the isolator with the circuit ID, never what room it feeds. I've never seen one labeled with that.

This is where the regs come in. It states that it should be clearly labeled as to what it's isolating if not obvious by position and it cannot be obvious by position as regards the internal unit. 

Twenty-eight years ago, back in 1992, I was on the good ship Discovery Bay/GYXG a first generation containership.  At the time that our annual Radio Survay was due, we were in Italy. The Italian Government Radio Surveyor decided that we required an isolation switch mounted adjacent to the radar scanner to prevent rotation. This in case whilst someone (a Radio Officer such as me, maybe?) was working on the radar scanner, someone else (a Navigating Officer or even the Captain...) turned on the radar in the wheelhouse - despite it being switched off and appropriate signs exhibited - (I never ever saw provision for locking off a radar) and the rotating scanner injures the said Radio Officer.


This isolation switch as apparently required by Italian law and certainly not UK law, did not stop the radar transmitter from operating and therefore, whilst once fitted and if used, I would not get hit by the scanner, but it was OK for me and/or whoever else was up there to get gently(?) microwaved by the radar transmission, X-Band (10GHz) or S-Band (3GHz) now from a stationary scanner...


It was likely a scam, since the requirement was for the Radio Survey to be carried out to the Flag State (UK) requirements, and luckily to avoid delay the Italian Survey had a couple of Italian Technicians in tow.....


Additionally, on other ships after the Discovery Bay, besides my day-job as Radio Officer I also found that monitoring and repair of integral refrigerated containers (ie those with built in refrigeration equipment), became one of my chores. Thus installing a split- aircon is not that much of a technical problem, say no more!


Clive

However, there is no term "local isolator" or "local isolation" in the regs.


I was about to post asking where "local isolator" appears in BS 7671, but on reading the topic, I see that you have corrected yourself!


Regards


BOD

(I would report these as code 3 but it would be changed to code 2 when we get the remedials list back)


Is this the input of the QS or DH if you're with the NICEIC?


Regards


BOD

No Idea. My company is NICEIC registered. Don't know what the two abbreviations you mentioned stand for. I don't get involved with that. I'm just a humble spark doing what I'm told guv'nor. 

We are told to report all situations that have "no local isolation". However, this could be on instruction or agreement with the client or it could just be their own opinion as to what should be reported on the obs.

Qualified Supervisor (QS) and (Principal) Duty Holder (PDH) who may be the same person but for bigger companies, usually different. The QS is the person who accompanies the Area Engineer (AE) on the NICEIC visit.

The QS countersigns the reports and certificates following the electrician's signing of them, to confirm his review of them as representing their accuracy......................


Regards


BOD

Ah! Those descriptions i have heard of but when mentioned as abbreviations I didn't recognize them.

Sorry, I try not to, but they slip through!


Regards


BOD