More EICR coding questions.

[brianmoooore]

My wife is on the committee of the local village, and they have just had an EICR carried out. This came out as 'unsatisfactory' and accompanied by a quote for remedials totalling well north of £9000, although this does include a fire alarm system (which, AFAIK, no one has suggested is required).
A number of the c2s refer to tails to two DBs being undersized.
The supply is single phase 100A, with the metering equipment in an external box. 25mm2 tails go through the wall to a 100 switch fuse, and from there more 25mm2 tails go through the roof of an extension to a point in the main hall where the meter was originally fitted. Henley blocks then distribute the power to four DBs.
25mm2 tails go to the two 'main' DBs, sited next to each other, and this is all deemed satisfactory.
Two other smaller DBs are also fed from the Henley blocks in 16mm2, and both of these are coded C2 as under rated for the designed load.
Tails to one are in surface mounted trunking, so method B, and the load comprises a small number of lights on a 6A MCB, a single 2G 13A s/socket on a 16 MCB, and two 32A blue sockets, each on a 32A MCB. Main switch is a 30mA RCD. (
32A sockets are for two stage lighting controllers, sold to them and installed by some shyster, with the aid of a grant, many years ago. They have precisely three stage lights, so the total load has never exceeded around three amps, and one 32A socket has never been, and never will be, used)
The other DB on 16mm2 tails has these running through a short length of the roof space, so Method A.
Load on this DB are some lights on a 6A MCB, a RFC on a 32A MCB, and a 3kW water heater (fixed load of 12A) on a 16A MCB. Main switch is, again, a 30mA RCD.

Comments, please.

 

[littlespark]

The C2’s aside…. The person doing the eicr doesn’t know if these 32A sockets are in use or not… they are part of the installation so have to be considered as such.

9k seems a hell of a lot for undersized tails, so what other work needs done?
The fire alarm system wouldn’t come under an eicr, only the mains supply to it.

 

[brianmoooore]

There is no fire alarm as yet, and as far as I know, neither the council or the fire authorities have requested one. It's just a two (large) room village hall, plus toilets and a kitchen, an has multiple fire escape exits on all sides. Difficult to see how a fire would go unnoticed for long enough to put the occupants in danger without an alarm.
Cost of the alarm is included in the quote.
Also included in the quote is replacement of all the emergency lights, which I'm not sure is strictly necessary or that they have been tested for endurance, but they are all outdated in that some use a small incandescant lamp and others use fluorescent tubes. A distress alarm is also included in the quote , for the disabled toilet.
There are a few other C2s, some of which should probably be C3s, but all are relatively easy and cheap to sort. I'll post on them later, after, hopefully, a few more comments on the tails.
My take is that the Method B tails are good for 76A and the Method A ones for 61A.
Design load on the first DB is 32A + 75% of 32A + 75% of 16A +lights = 68A +lights, so just within the Method B tails.
Design load on the second DB is 32A (RFC) + 12A (actual load of water heater) + lights = 44A + lights, which is well within the 61A rating of the tails.

 

[westward10]

The fact it has multiple escape routes may not be overly relevant. Absence of an automatic fire detection system is acceptable if the fire can be observed giving an individual an acceptable time to escape the premises. The fact there are WCs probably eliminates this but a fire risk assessment is required.
Emergency lighting is deemed a safety system and as such requires routine testing by a responsible person.
The above are not applicable to an EICR and they are probably fishing for work so in the case of the fire alarm I would be requesting their fire risk assessment so you can consider their proposal.
Personally I would say the 16.0 conductors are undersized in relation to the 100A protective device, would I C2 it, yes.

 

[Fender]

westward10 is correct regarding emergency lights and fire alarm. Nothing much to do with an EICR, as long as the 230 volt wiring and accessories comply. The need for a distress alarm on an EICR is a new one on me. Absolute rubbish.

However, the undersized 16mm is an interesting one. I think a few considerations should be looked at.
What are the chances of of the 16mm cables being subjected to their maximum current capacity?
Is it likely that new equipment could be added that would create the above scenario?
How long has the 16mm been installed and is there any sign of thermal damage?

After answering these questions, the maximum measured Zs would need to be looked at. If it's below 0.34 ohms (assuming a 'normal' BS 88 fuse fitted) then disconnection times in a fault are met.

So although a 100 A fuse is oversized for the cable, does it really warrant a Code 2?

Without seeing the set up (it's a village hall, not an industrial plant) I would be inclined towards a Code 3.

BS 7671 makes reference to this 433.3.1 (ii)

Could be wrong though

 

[timhoward]

Great questions, and looking at the whole picture is always healthy.

So although a 100 A fuse is oversized for the cable, does it really warrant a Code 2?

I'd still say yes I'm afraid!
It's one of those that we all know that in practise is effectively safe due to the limited loads, but the CCC of the tails relative to their protective device will never get a tick.
I haven't looked it up but assuming 433.3.1 (ii) is the fixed resistive load / omitting overload protection reg, the 2 x 32A sockets pretty much kill that concept in my mind as we never know what one day they might be used for. (silly example - charging two EV's ?!).

If the 32A sockets weren't there, then we would indeed have completely predictable loads with exception of one double socket protected by a 16A breaker, and the argument stacks up much better in my mind.
With the 32A sockets there the variation of potential load current is simply too great to claim it will never be an issue, in spite of the typical use today being known.
If the 32A socket that will 'never be used' was removed, and the 'max 3A stage lighting load' was de-rated to a 16A or 13A socket I might be convinced it's a C3.

 

[Strima]

As the DBs aren't a fixed load you cannot guarantee the CCC of the cables will not be exceeded in the future if any additions are made, C2 for me. TBH I would either look at replacing the tails or fitting a switch fuse.

 

[Dartlec]

I could see that in a village hall situation a company wanting to cover themselves might err on the side of a C2 given what's installed - though in the practical circumstances described the actual 'risk' seems low to negligible.

The easy answer to resolve the issue would seem to be to blank off or disconnect one of the 32A MCBs for the unused socket, and perhaps downrate the other socket (or perhaps the MCB).

That shouldn't cost more than an hour or two of work, so anything quoting higher than that seems extravagant.

Since this isn't domestic, I'm not sure of the ramifications of not even fixing it though - perhaps insurance related, though it's likely not actually written into any terms and conditions that a satisfactory EICR must be in place?

 

[timhoward]

Since this isn't domestic, I'm not sure of the ramifications of not even fixing it though - perhaps insurance related, though it's likely not actually written into any terms and conditions that a satisfactory EICR must be in place?

Yes, the two parties interested would be insurance, and indirectly the fire-service.
Insurance would be sending a loss adjuster after a claim and arguing the defects found in fixed wiring inspection weren't corrected.
As far as I remember the fixed wiring being inspected is also normally a mitigating factor mentioned on the mandatory risk assessment for a "place of assembly" to satisfy the 2005 Fire Regulatory Reform Act, and a fire service inspection (rare to non-existent in practise) would also ask the question.

 

[Dartlec]

Yes, the two parties interested would be insurance, and indirectly the fire-service.
Insurance would be sending a loss adjuster after a claim and arguing the defects found in fixed wiring inspection weren't corrected.
As far as I remember the fixed wiring being inspected is also normally a mitigating factor mentioned on the mandatory risk assessment for a "place of assembly" to satisfy the 2005 Fire Regulatory Reform Act, and a fire service inspection (rare to non-existent in practise) would also ask the question.

If there isn't a fire alarm in place at the moment I suspect they might look more carefully at that if there was an incident though, rather than whether there was an EICR in place?

Clearly having a satisfactory EICR is a very good way of proving that you are meeting all sorts of mandatory requirements to be 'safe' - just interested in the mechanics when it's not domestic - or more specifically PRS which is (badly) specifically mandated as we know.

Would a risk assessment that the C2 items are low risk and not time critical and will be dealt with in the next year, for example, be considered acceptable? There are no time limits specified for remedial action in the regulations for EICRs outside of PRS are there?

 

[westward10]

Forget PRS when it comes to commercial periodics outside of this scope. Code 2 requires "Urgent Attention" and there is no recommended period of time, it is urgent.

 

[Lucien Nunes]

Strictly speaking we should be visualising these cables as a conventional distribution circuit, rather than meter tails, as they are protected by the customer's switchfuse.

32A socket outlets intended for entertainment lighting are often fully loaded. If I go into a venue with my own equipment and I see two 32A sockets, I will check the upstream to make sure the total is not limited to less than 64A (e.g. by other essential load on the same 100A SF) but otherwise use all 64A. The maximum load on this DB therefore exceeds the rating of the distribution circuit but only by a small margin, perhaps 5%. This translates into a 10% excess temperature rise, but probably for a few minutes per year when pushing everything to full for the finale. The cables are likely to be more or less unloaded for 99% of the rest of the time and could be expected to last their full design life. Whilst technically non-compliant, I cannot see any hazard at C2 level (actually I cannot see any hazard.)

IMO a circuit sufficient for the total installed load on a DB is adequately protected against overload by the downstream OCPD, provided it is also adequately protected against faults by the usptream (which it invariably is.) Therefore the board with 44A outgoing is fine on 16mm². If someone wants to come along and install a shower on the board at a later date, they need to check the adequacy of the supply equipment including the distribution circuit, and at that point the CCC of the 16mm² would show up as a factor requiring upgrade.

 

[timhoward]

Lucien's post has made revisit the original information and I now see I made an mistake when I read the original posts- I had believed the design loads quoted were based around the 3A of lighting and an empty 2nd 32A socket, so was mentally adding two maxed out 32A sockets to the totals.
Now I see (as pointed out) that the design loads are within the CCC of their cables I do feel that C2 is over-stating any potential danger.
It's also in the back of my mind that in different circumstances with this all connected nearer the origin reg 433.2.2 would render this compliant (fault protection in place and <=3m conductor length allows overload device to be downstream).
It would probably be best to resolve the issue that could crop up at every inspection and add upstream fusing, as once upon a time someone once shouldn't have fitted the 16mm conductors with an 100A upstream fuse.

 

[brianmoooore]

I see my thread has suddenly sprung to life after lying dormant for a couple of weeks!

My take is that the Method B tails are good for 76A and the Method A ones for 61A.
Design load on the first DB is 32A + 75% of 32A + 75% of 16A +lights = 68A +lights, so just within the Method B tails.
Design load on the second DB is 32A (RFC) + 12A (actual load of water heater) + lights = 44A + lights, which is well within the 61A rating of the tails.

Does anyone agree/disagree with the quote above? I've used a diversity factor (commercial building) of 100% of largest socket circuit + 75% of other socket circuits for the first DB and no diversity for the second, since it only has one socket circuit.
Lighting load on both is minimal - the lighting circuit only serves 3 or 4 lights on each.

 

[timhoward]

It seems fair enough. (If you stuck the 2nd unused 32A socket feed in the cpc bar I think the first DB would be way under the CCC of the supply cable without any diversity.)
I'm not concerned about it's safety at all, it will just always look wrong.
If the main switch on the DB's were two pole 50A RCBO's then it would be an easier argument that an entire CU is a fixed (or at least limited) load! Probably not a practical solution though.