Socket circuits and SANS 10142

[dsmossbw]

I am not familiar with the SANS wiring of premises regulations but have been told that socket circuits having the following configuration comply with SANS 10142, these are:

A ring circuit wired with 2.5mm2 cables, protected by a 30A RCBO and using SANS 164-4 socket outlets and,

A ring circuit wired with 2.5mm2 cables, protected by a 30A RCBO and using a mixture of SANS 164-1 and BS 1363 socket outlets.

Confirmation or otherwise that these circuit arrangements do or do not comply with SANS 10142 would be greatly appreciated.

Regards
David

[GCE]

Hi

The SANS 164-4 socket is commonly referred to as a Dedicated socket and does not need to be protected by an RCBO ( Earth Leakage unit) but by a C/breaker only.Can only be used for critical applications as listed (6.15.1.1.4 )

The SANS 164-1 is our standard 16 Amp round pin socket and must be protected by earth leakage and since Jan 2018 can only be installed alongside a SANS 164-2 socket ( "euro socket outlet") ( 6.15.1.1.1 )

The BS1363 socket ( square pin 13Amp ) may not be used in SA installations as from Jan 2011 ( was a note in SANS10142 edition 1.8 Amdt 8 - may no longer be sold in SA)

6.15.8 - Each socket in a ring circuit shall be marked as such.

6.15.2.2 - Anticipated load of a circuit that feeds socket outlets shall not exceed 5Kw -

6.15.3 c - shall if the circuit protection is rated at more than 20Amp , use only protected socket outlets etc etc

Generally the C/breaker protection on the socket may not be more than 125% of the rating of that socket ( 6.15.5 b ) The sockets are generally rated at 16Amp

Table 6.27 - Max protection rating of 2,5sqmm wiring is 25Amp - Remember manufactures specification may be more stringent

The answer in short form - you would need to use 20Amp maximum protection ( unless the sockets are individually protected) and ensure that all sockets are labelled accordingly - you may not use BS 1363 sockets

I cannot remember ever coming across a ring circuit ( and I have been around the block) and would think that it is not cost effective vs just installing an extra circuit

[dsmossbw]

Thank you GCE for your response, it is very informative and helpful but I wonder if you could help me a little further with an issue?

You mention clause 6.15.1.2.4 and the omission of an RCBO for critical applications. I see that the clause lists applications such as emergency lighting, a deep freezer, a burglar alarm, data processing equipment or life-supporting equipment. I looked for but cannot find a definition in the document for data processing equipment so I would be interested to know your opinion on whether an everyday desktop or laptop computer being used as a workstation in an office falls into the category of critical data-processing equipment?

Thanks in anticipation.

Regards
David

[GCE]

Hi David

Desktop computer , printer ,laptop , server , router , UPS etc would all fall under Data processing equipment -

[dsmossbw]

Good evening GCE

Thanks for your response.

I must admit I find it a little difficult to categorise desktop computer as critical equipment along with life-supporting equipment? However, it seems to me, from what you have told me already that in the context of this project, ring circuits protected with a 30A SP CB using SANS 164-4 circuit accessories still does not comply to SANS 10142.

I was also wondering what your view is regarding a Consultant Engineer taking bits from BS 7671 and SANS 10142 and saying that different parts of the installation conform to particular clauses of one or other standard and therefore the installation as a whole conforms?

I would appreciate your comments.

Regards
David

[AndyD]

A standard desktop PC wouldn't qualify as critical equipment.

I think part of the problem with the SANS regs and the ring circuits is that, unlike the UK, in SA we don't have fused plugs so appliance flex faults often struggle to make disconnect times even on a 20Amp radial. If it was a 2.5mm ring circuit with a 32A OCPD, which is the UK norm, then an appliance flex fault on a 0.5mm flex might not even trip at all depending on the flex length, at best it would still take too long to clear the fault. Consequently ring circuits are highly regulated in their acceptable use and generally best avioded in most circumstances in SA with SANS 164-4 and SANS 164-1 socket outlets .

If you're in Gabarone I'd guess the installation would need to conform to whatever standards are recognised there although there may be exceptions such as foreign military bases or embassies etc which are always grey areas. Bottom line, if the consultant is responsible for legally signing off the installation I'd get his instructions regarding mixing UK and SA standards in writing then go ahead according to those instructions. If you're responsible for legally signing off the installation then I'd suggest you take your cue from the local legislation and tell the consultant (and client if necessary) you're being pressured to do something you regard as illegal.

[Dave A]

I was also wondering what your view is regarding a Consultant Engineer taking bits from BS 7671 and SANS 10142 and saying that different parts of the installation conform to particular clauses of one or other standard and therefore the installation as a whole conforms?

Conforms to what (quality standard)?

The best (and shortest) definition of quality I know is "Consistently meeting a set standard".

From a strict compliance point of view, where there is overlap, one would expect compliance with both standards claimed.
Otherwise you're cherry picking - which starts begging the question - why?

[GCE]

[QUOTE=AndyD;143940]A standard desktop PC wouldn't qualify as critical equipment.

Hi Andy
Are you saying that you would not put a dedicated socket in for a desktop PC in an office situation , even at home ?

[GCE]

HI

The question with regards to mixing standards - Seems to be a problem in Africa with no sets standards for the countries like Botswana , Namibia etc .
They seem to be borrowing different standards based on opinion and the country of origin that the consultant comes from along with mainly the British code due to colonization.Seems to be an ongoing complaint among contractors working in Africa.

The problem is only going to be solved when the various governments adopt and gazette a set standard to adhere to.Going to be a long journey and contractors in those countries do not seem keen to have outside interference which we would regard as help.

If we take SA with SANS 10142 making an attempt to move towards the IEC codes but still wanting to retain an independent input unique to SA.
It will be difficult to expect the rest to simply adopt another countries code and gazette it, so that everybody is working to the same endpoint.

[AndyD]

A standard desktop PC wouldn't qualify as critical equipment.

Hi Andy
Are you saying that you would not put a dedicated socket in for a desktop PC in an office situation , even at home ?

Not likely in a home because to avoid requiring RCD protection on that circuit all sockets would need to be the red dedicated type. An office environment may warrant the installation of dedicated circuits but offices with mission critical IT equipment are usually going to have a central UPS back-up.