16th PIR Codes

[Pensdown]

A customer has asked me to review and comment on a PIR that was carried by their national maintenance company. It was carried out to the 16th in May.

The building is just over 5 years old and is spread across 3 floors.

I'd like your expert opinions on some of the codes before I make my own mind up. I wont tell you what codes were given just yet, only my opinion.

High Zs - The circuits were mainly split air con unit with 20amp D type MCB's The average readings were a few ohms above the corrected values but within table 41.3 IMO Code 2

Shared Circuit - Within the Comms Room there is an original 10amp radial circuit feeding a FCU for a high temp alarm. Someone has added a water detection panel and the feed has been taken directly from the MCB feeding the high temp alarm. The new circuit has been wired in 2.5mm FP200 to a FCU. IMO no code as it's allowed.

20mm Hole in the top of a 200amp MEM switched fuse within a locked Switch Room - IMO code 2

Thanks in advance

 

[securespark]

I guess the co. that did it were NIC, they are fussy about shared circuits. They did not recognise the stuff in the 16th OSG about radials etc...

I agree with you re no 2, but the others I may be tempted towards a 1. It's a tricky call. You don't want to underestimate the potential of the defect.

 

[GaryMo]

High Zs - The circuits were mainly split air con unit with 20amp D type MCB's The average readings were a few ohms above the corrected values but within table 41.3 IMO Code 2

If the PIR was carried out in accordance with BS7671:2001 then shouldn't table 41B2(g) be referenced?
Max values were based on 240v in the 16th ED so figures may be more favourable (0.60ohms against 0.57ohms).
I assumed you meant that readings were a few milliohms above the corrected values and not ohms?

 

[ericmark]

I do agree that it is hard to code faults as basically code 4 is if it only is considered a fault in today’s regulations and not in previous editions and I see no code 4 in any of what you relate. Code 3 is where we for some reason can’t test again nothing in your faults that come into that. And Code 1 is immediate danger and nothing comes into that group so all faults would get a Code 2 so only question is it a fault.
High Zs yes I suppose even if close would have to be listed as fault.
Radials can be split shown on 17th Corrigenda July 2008 so no fault.
20mm hole tricky one in locked switch room I would consider as a fault but if one considered the whole switch room as an enclosure then it could be argued as no fault but I would consider as fault as working in switch room even an electrician could in error drop something down the hole.
The problem is there seems to be a few Code listings and to me our PIR’s should include an interpretation of what the codes mean in the same way as we include the “Guidance for Recipients” on IEE forms which only codes are reference to code of practice and postcode. And although using the 1 to 4 coding method as given by the “Electrical safety council” is a good idea a copy of at least the part of BPG4_08.pdf on page 8 which refers to Codes should be included in the report.
In other words the codes are meaningless without at least a reference to what the codes mean.
Eric

 

[Pensdown]

Gary - I did mean Milliohms

This is their summary sheet

Untitled

• Pensdown
• 5 Dec 2008
• 1

 

[GaryMo]

RCBO not tripping in time - code 1

 

[Pensdown]

...nearly as funny as the £ 8,255.00 quote to carry out the remedial work...

 

[Spark123]

What is the purpose of the RCD and what are the trip times? Probably lean towards a 2 for that one however need to know the full story.
No 1 If there is access to live parts then fair enough with code 1, if there is no access to live parts and very little risk to persons, property etc then code 2
No 2 as No 1
No 3 is a bit strange - faulty so unable to test???
No 9 need more info
No 10 - not really a problem as long as it is sized correctly and reg 314 is met
No 11 - Code 1 if I am reading what it says correctly. Also immediate danger notice.
No 23 as No 1
No 35 - code 2
No 37 - need more info
By now I'd be asking if I am testing the RCBOs correctly and the tester is OK!

 

[jason1958]

> High Zs - The circuits were mainly split air con unit with 20amp D type
> MCB's The average readings were a few ohms above the corrected
> values but within table 41.3 IMO Code 2

Is the measured EFLI <80% of that required for 20A Type-D?

The 80% figure is used "because Ze may deviate".


> Shared Circuit - Within the Comms Room there is an original 10amp
> radial circuit feeding a FCU for a high temp alarm. Someone has added
> a water detection panel and the feed has been taken directly from the
> MCB feeding the high temp alarm. The new circuit has been wired in
> 2.5mm FP200 to a FCU. IMO no code as it's allowed.

Shared circuit re no discrimination between two alarms?

Shared circuit re two wires into one CPD?
- Radial f.c. can have any topology - including >1 wire into 1 CPD
- However some NICEIC believe that this is not permitted because it may appear to be a Ring f.c. and will appear as a broken Ring when tested
- To remove this perception the Radial must be labelled as such

Likewise 2.5mm FTE Ring may be fed by 6mm FTE Radial - used where extreme insulation levels encountered, certainly listed in the 16th OSG.


Up to you 1) what corrective action you have done, if any and 2) if you use the company doing the PIR to also do any recommended works

 

[jason1958]

To add, exactly how was the EFLI measured?

Fruit machine?
- EFLI meter with fruit machine result chosen to produce code?
Measured?
- High current measured Ze, dead R1+R2 measurement, added for Zs?


EFLI meters fall into 2 camps...
- High current tests -- useful to verifying if the earth will handle 25A
- Low current algorithm -- require careful understanding of errors

In a low current EFLI test L-E or N-E are subject to a tiny current & a microprocessor calculates EFLI by an algorithm. Under a sensitivity analysis the algorithm is poor - that is results are poorly reproduceable and may deviate wildly from a high current test. First - Imagine a raise-to-the-power-of-two mathetmatical operation applied repeatedly, a slight change in the input will result in a large change in the result. Second - Imagine the input as being very small, so small in fact that noise is of a similar or even greater magnitude. Combine these two and many EFLI meters create fruit machine results (or create results someone wants).

As you get closer to a Tx the EFLI results increasingly become nonsense, and likewise this is particularly acute with Type-D breakers requiring very low EFLI which is then subject to an 80% figure.

The increase in use of RCD is driving people to low current EFLI testing, but the early meters were truly terrible (LT7 hilarious with fluorescent lighting nearby, the noise simply produced near random pass/fail results a factor of 5 away from the high current test).

 

[Pensdown]

By now I'd be asking if I am testing the RCBOs correctly and the tester is OK!

I think you've nailed the problem because reading in more detail most of the circuit Zs values are lower than the Zdb value. One of the testers must be faulty. Either the one with a display or the one using it!

If I get time tomorrow I will scan the test sheets because they do make interesting reading.

 

[GaryMo]

Is the measured EFLI <80% of that required for 20A Type-D?

The 80% figure is used "because Ze may deviate".

No it's not, it's to take into account the increase of resistance of the conductors with the increase of temperature due to load current.
It's nothing at all to do with Ze deviating.

Have a read of App 14 for more information.

 

[GaryMo]

I think you've nailed the problem because reading in more detail most of the circuit Zs values are lower than the Zdb value.

Parallel earths?

 

[Pensdown]

I wouldn't rule parallel earths out but I do suspect operator error.

The nice thing is I've just been sent a copy of the original EIC for the building. Rather than post try and post them I will up-load a copy of the PIR and the EIC to our web portal.

If anyone wants a copy for toilet reading just drop me a mail and I will send you login details.

No 11 - Code 1 if I am reading what it says correctly. Also immediate danger notice.

You're reading what they've written correctly but what they've written is some what misleading

At some stage someone has installed a clean earth bar in the Comms Room. Rather than wire it back to the MET, it's been linked to the earth bar in the distribution board. As you can see from the image, I also questioned that straight away.

 

[ericmark]

You said building 5 years old and PIR done before 30st June 2008 which means tested to BS7671:2001 which was also in force when the building was built which means there can be no Code 4 faults.
36 DB LP3B No sleeving to ID neutral & CPC conductors
40 All tap off isolators in risers need to be labelled
41 All DB’s need appropriate voltages stickers
Are all reported as Code 4 which can only mean the compilers of the report have not used the Electrical Safety Councils recommended codes.
Which reinforces what I said before that to use a code system one must also include what each of the codes mean.
Only 43 All DB’s need two versions labels where appropriate could really be given a Code 4 as the colours have changed in the regulations since it was built but this gets a Code 2
So if we said for example.
Code 1 Requires attention
Code 2 Requires improvement with labels earths and locks
Code 3 Unable to test
Code 4 Low priority labels missing
Then it would seem OK (Note dropping of Urgent) but if one was to follow the Electrical Safety Council coding then with so many code 1 faults the building should have been closed down. To have so many RCBO does not trip in time faults rings alarm bells as I have so many times seen those without their C&G2391 test RCD’s at tripping level rather than 5 x tripping level to measure time and being such a simple job to re-test I would start there to see if it has been done by a skilled or semi-skilled person.
Also what you show is not really a schedule of test results which would show RCD time in ms etc. I had a similar problem with a hotel and I had to make it very clear that without a copy of the schedule of test results I would need to do the PIR again this is still on going.
Eric