I have recently been asked to quote for a periodic inspection on a livestock market and was wondering if anyone could help me as for what to look out for thats different to your everyday domestic or commercial periodic inspection.

any help and advise would be MUCH appreciated!

start with a good read through Section 705 and the relevant section of Guidance note 7.

key considerations will be RCD protection, supplementay equipotential bonding, IP ratings and the environmental conditions and corrosion, corrosion, corrosion

OMS

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Failure is always an option

Thanks OMS, Is there any difference in specific circuits that need RCD compared to ur regular periodic, i have been round the premises this morning and had a good scout round it was originally built in 1991 and is all done in MEM memsheild and there is not 1 RCD or RCBO in the whole building. also same with bonding is there any extra specific places it should be.

Thanks
Josh

As I said, try section 705.

705.411.1 - in summary you should have 30mA RCD protection on all socket outlet circuits less than 32A, 100mA on all final circuits supplying socket outlets gretaer than 32A and 300mA on all other circuits - this regardless of earthing type

705.415.2.1 - in summary, all exposed conductive parts and all extraneous conductive parts including any floor mesh should be supplementary bonded

You should not be making use of the PME terminal if it exists

Regards

OMS

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Failure is always an option

Smashing! thank you very much BIG BIG help! going be alot of remedials then by the sounds of things... :)

LoL - you'll be asking me what code next

Good luck with the bid

regards

OMS

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Failure is always an option

If there is livestock present be careful when undertaking tests, especially loop Impedance tests as this could be dangerous especially if there is an absence of supplementary bonding.

thanks boyobach.

Also bear in mind IP rating of accessories (switches/sockets) and the accessibility of these to passing livestock - They love a chew.

Light fittings should also be protected to prevent hot debris falling into pens where straw could be present


Stu

I know that you said "thank you" to OMS,

but he cant`t spend a "thank you" !




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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

--"all extraneous conductive parts, including any floor mesh should be
supplementary bonded"

is that correct?

regards.

LoL -

I thought you supply industry types knew everything

OMS

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Failure is always an option

Edited: 11 June 2012 at 10:29 AM by OMS

Although I wouldn't recommend it. I thought the PME terminal could be considered for use, if a suitable metal grid was laid in the floor and connected to the earthing/bonding network.

Regards

You could use the PME terminal - but as you say, you wouldn't realy want to.

Regards

OMS

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Failure is always an option

--"I thought you supply industry types knew everything"

thank you for telling us the "reg/req no for supplementary bonding.
just so I am clear, as this metal grid is an extraneous conductive part,
ie embedded in a concrete floor, it requires a minimum of 10sqmm
as it is a "main bond"

Regards

No, not if I was installing it from new.

I'd go with reg 542.2.3 (v) if it is welded metal reinforcement of concrete and use it as the electrode for a TT installation and select a main earth conductor to connect it to the MET from table 54.1 (both on page 159), so that leaves the size of conductor open to discussion.

Regards Andy

--we are not talking about re-inforcing concrete we are talking about the
difference between "main bonds" and "supplementary bonds"

"page 220=
metallic grid with at least two welded joints laid in the floor to form an
extraneous conductive-part for the purpose of equipotential bonding.

and as I mentioned in my lighting column comments last week, main bonding conductors (exepting PME) are 6sqmm---25sqmm.

but then, we know that.

Regards

I beg to differ, if you read the regs book as written, either way there needs to be a conductor between the MET and the concrete floor reinforcing. If it is PME we HAVE to have a a supplementary equipotential bond to the floor reinforcing. If it is TT then we still have to HAVE the supplementary bond to the floor reinforcing, but it can be the main earth conductor as well, because the reinforcing can be the earth electrode. There is then the recommendation that if there is no reinforcing in the floor you don't use the PME earth if it is available and go for TT.

TT has to be the preferred option, now the practicality of connecting a earth to the reinforcing retrospectively after it is installed is uncertain. Chances are it was just thrown down as the concrete lorry drove forward discharging its load with no thought to making a sound electrical connection between them, so chopping a hole in the floor and earthing a piece of exposed reinforcing will in no way ensure the entire floor is well earthed.

Andy

Remember 705.411.1 requires RCDs on everything, so what would be the advantage of using the PME terminal?

Edited: 11 June 2012 at 10:54 PM by sparkingchip

705.415.2.1 states supplementary bonding of the location. The diagram on page 220 is titled example of supplementary bonding within a cattle shed 705.544.2 iii requires minimum 4mm copper. Maybe this will be made clearer in the next amendment. Regards

For once, I've got to agree with UKPN - while 705.415.2.1 talks about extensive supplementary bonding, all of the chapter 7 sections 'supplement or modify' the main regulations (rather than replace them) - so 411.3.1.2 (main bonding) would still apply to a cattle shed as much as any other building - so any extraneous-conductive-parts that may introduce a potential from outside of the installation (as I suspect a floor grid for example would) would need main bonding. They may well also require supplementary bonding (but the requirements of 415.2.2 may well be satisfied by the main bonding conductors & c.p.c.s anyway).
- Andy.