Exposed parts near mcb and meter

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Dan L
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Exposed parts near mcb and meter

Post by Dan L »

3.10.1.1.c

My understanding of this was if you need to enter an enclosure like a meter box to operate an mcb or fuse or read a meter (non smart meter) then you can not have basic Insulation or exposed live parts like a neutral bar in this enclosure it must be double insulation and neutral bar would have to be seperately enclosed or behind a panel.

There's a builders temp that has neutral bar, meter isolation mcb and neutral/earth bar in same enclosure. The rest is mounted externally on side of box.

So under normal operation of mcb and reading meter neutral bar and single insulation can be touchdd.

I feel like it's non compliant for this reason but some would disagree.

All I can find is 3.10.1.1 c.

Do you know any other relevant references and what are your thoughts on this

Thanks.
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DougP
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Re: Exposed parts near mcb and meter

Post by DougP »

Your reference to single insulation is correct. But the neutral bar in a MEN switchboard is not a live part. 1.4.63
Dan L
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Re: Exposed parts near mcb and meter

Post by Dan L »

Does the main neutral bar not need to be enclosed as in must need a tool to access it? I feel like iv read this somewhere or maybe it's just because this is normally how sb are set up
AlecK
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Re: Exposed parts near mcb and meter

Post by AlecK »

Yes 3.10.1.1 (c) allows for single insulation within enclosures provided such parts are not 'exposed to touch" during normal operations.

In this case all the MSB & BTS type operations are external to the meter enclosure; so it can be treated same as a normal meter enclosure.
The mcb being there only for isolation of meters doesn't count as "normal switching"; but meter reading counts.
So any parts accessible with the door / lid open (ie accessible to non-electrical workers) must be more than single-insulated.

Doug's correct WRT the N-bar not being regarded as a "live part" under the definition in "3000".
However ESR 4 states that a N conductor is always a live conductor;
and as per ESR 4( 2) definitions in Act / ESRs take precedence over definitions on Standards.

We could discuss whether the N-Bar & MEN link are "conductors" [my interpretation of 1.4.31 says they are];
but regardless there must be other conductors to / from it, so the rule applies.

The enclosure needs to be set up to require use of a tool / key. 1.5.4.4 (b)(i) refers.
That makes reading the meter impossible, so must install a window.

Bottom line: the installation is non-compliant (but not necessarily electrically unsafe).
Accordingly if you are the Inspector you should issue a "fail" RoI - or at least suspend your inspection pending correction of fault(s).

If already operational; it will be recorded on the HRW database, you can find out who installed it and which Inspector issued the RoI.
Dan L
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Re: Exposed parts near mcb and meter

Post by Dan L »

Some follow-up questions

If it was a smart meter because under normal operating conditions they are read remotely via 4g no meter reader required. Does that mean it would be OK in this situation?

2 - so in general does a neutral bar always have to be enclosed (tool to access) to be compliant.

Thanks for feedback all. Much appreciated

And in regard to the bts in question this style has been going around for a while now and passed many times by different inspectors.
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Re: Exposed parts near mcb and meter

Post by AlecK »

1: No. Even with so-called "smart" meters, some readings are manual.

2: Yes (for new installations)

3: while "BTS" units are often re-used; each time they are installed is installation PEW and they need to be compliant with current requirements. The idea that they can be treated as an 'existing installation' under ESR 113 is wrong. While ESR 113 allows for re-use of the existing fittings that make up a BTS, the unit as a whole must comply.

Which is at the heart of the arguments about relocated houses (& other installations). Noting that the key identifier when certifying PEW is the location ; it's very difficult to make a case that a new site can be the same installation.

And it's unfortunately true that many people who hold "Inspector" licences are less competent than they should be (to put it politely). A prime example of this being WoEFs issued by "Inspectors" for caravans that have Type AC RCDs (it doesn't take much to notice that the marking is wrong).
Dan L
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Re: Exposed parts near mcb and meter

Post by Dan L »

The first time I seen this temp alarm bells rang for me. Its good to have the information to back this up. Much appreciated.
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