What would the code be for an isolator switch of a distribution board not having any indication of its position(on or off)?
There are two distribution boards at the origin, one is off when down, the other is off when up. One isn't labelled or marked any way.
Also, would you code for no single point of isolation for the whole installation?
Would you classify the main switch on a DB as an emergency switch ? The main switch is an isolator that I evaluate during an EICR based on the following criteria in part 9 (7.1):
When it comes to The emergency switching off (7.3) a device that can control the supply to circuits or equipment to remove a danger that has occurred unexpectedly. I am mainly concerned with emergency stop buttons. As per Guidance notes 2, some examples of emergency switching are:
Hence, I would inspect the following aspects for the emergency switching off:
Modifying in the same sense that we modify a DB when we label the circuits?
514.1.1 seems to be relevant, but that requires the purpose of each item of switchgear and control gear to be identified. So there should be a label for "main switch".
My old Federal Electric DB is not entirely clear, but on close inspection, "1" is visible when the dolly is up and "0" when it is down. By contrast my modern main switch has a green/red flag.
There is scope for confusion in UK where at least the lay person is used to down for on. Traffic lights are green for go, which is not necessarily safe; and red for stop, which is not necessarily dangerous.
My understanding of a C2 on an EICR means that something on your installation is POTENTIONALLY dangerous
To my mind it's a bit more nuanced than that - yes, something C2 is potentially dangerous, but not everything that's potentially dangerous is a C2. A BC or ES lampholder is potentially dangerous (you can put fingers on live parts), but not codeable at all. My personal rule of thumb is to think about the usual levels of shock protection (i.e. we typically ask for two faults to danger) - no protection (e.g. exposed hazardous live parts) would be C1, lack of a 2nd layer (e.g. lack of earthing or double insulation, but basic insulation intact) would be C2, lack of 3rd layer (e.g. additional protection missing, but ADS/double insulation OK) would be C3. Of course, there are exception (or refinements) to those rules, sockets feeding extension leads outdoors would be a C2 rather than C3 without 30mA RCD protection as the length of leads means you can't control Zs and therefore guarantee ADS (quite apart from the lack of additional protection per se). Likewise lack of additional protection in bathrooms (both RCD and supp bonding absent) would be a C2 because normal ADS doesn't provide the same level of shock protection in the wet/naked/barefoot conditions.
I'm quite surprised that a DB or CU lacks an indication of which way is off - it seems to have been the norm even going back to the days of cast iron side handled fuse boxes. The Wylex CUs often had a bit of loose plate hanging on the switch dolly just behind the front cover that would indicate ON/OFF in the bit of the hole the dolly wasn't covering - loss something of that might have more implications in that internal parts that should have had some covering could be exposed. (Like loosing the coloured dots from rewireable fuse carriers - which left a live fixing screw exposed.)
- Andy.
Of course it would be easiest to mark them up, but it's one of many many non compliances. They just want the report for now. If a main isolator switch on a DB is classed as an emergency switch, then that's where I was wondering if it's more than a C3, in addition to the possible confusion with it switching the opposite way to the other DB.
Reg 462.2 Isolation of all LIVE conductors (so L and N)
except as detailed in 461.2 - so for TN systems generally, isolation of N is NOT required (other than for the main switch of single-phase domestics).
- Andy.
Interesting question.
Personally I would say a C2 on the EICR. As you state 2 CU/DB in close proximity with the OFF in different positions which COULD cause confusion at the best of times but consider the confusion during an emergency, in turn you are heighlighting a possible risk.
My understanding of a C2 on an EICR means that something on your installation is POTENTIONALLY dangerous
Think about Hierarchy of Controls
Elimination
Substitution
Engineering controls
Administrative controls
Personal protective equipment (PPE)
By adding a robust label for the ON and OFF for BOTH CU/DB you could drop this down to a C3, the caveat here is you are altering the original design and spec of the Iso. Eg the unit may become warm and your label could fall off or could potentially cause a fire risk. Further worth noting the age of the isolators and if they are double or 4 pole in the case of 3P&N so the C3 could recommend the isolator be upgraded in time to the current spec of BS7671
Reg 462.2 Isolation of all LIVE conductors (so L and N)
It would be interesting if you could add some pictures of the DBs.
As very few of the general public will have the iso guide to switch symbols to hand, in an English speaking environment, I'd strongly prefer the words "on" to indicate the on (alive) position and "off" for the off (dead) position. (I have no problem with ein / aus for Germans.. ).
Why a completed circle should indicate a broken circuit has never been especially intuitive to me, and and allusions to binary are wonderful but in many systems I have seen the switches are actually wired as active low, open pull-up, as that saves taking power to the front panel.
Mike.
In my vie simply marking ON/OFF or 0 and 1 would be fine and I consider that regarding this as a modification is over pedantic.
Every installation needs a single point of isolation, but more than one installation is permitted in the same building. So no code needed for the two main switches.
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