Another shower upgrade query

[Risteard]

As has been said, I don't think it was all that uncommon in the early days of (low-powered) electric showers.

Not here - but then in fairness it's a cable size which has never been stocked here.

 

[Risteard]

It was very common in the days of the first electric showers, which were often sub 7kW. I have seen loads of shower circuits run in 4 Milli and installed by Norweb (as was then).
Many were Dolphin Showers, installed in the 70s. Sometimes they had a Dolphin shower enclosure ( you had to have a bob or two), or more often installed over the bath.

Not here - wholesalers never stocked it here.

 

[sparkwright]

4 square is hardly a common size for a shower. In fact I would suggest that it's vanishingly rare to come across.

Loads of showers were done in 4mm2 in the early 80s. Southern Electric used to do them, in 4 mm2. Always finding them.

 

[Taylortwocities]

Not here - wholesalers never stocked it here.

But you aren't in the UK (or are you?). Probably its not stocked in Sri Lanka, or Congo either....

 

[SUNRAY]

4 square is hardly a common size for a shower. In fact I would suggest that it's vanishingly rare to come across.

I thought '4 square' is a a typical ceilidh dance.

I'll go further than the others and say that for many years 4.0mm² was THE ONLY SIZE of cable used for showers until well after larger than 8.5KW became common. I'll go further and say in my experience; a 10.5KW running on 4.0mm² is in the top 5 C1's on EICRs.

 

[JohnW2]

.... I'll go further and say in my experience; a 10.5KW running on 4.0mm² is in the top 5 C1's on EICRs.

Does that really qualify as "C1" ?

 

[ericmark]

Does that really qualify as "C1" ?

I would say no, unless the fuse/MCB/RCBO had been modified, however if we look at the chart, ref 100 which is normal, 27 amp is the rating, so only ref C would allow the use of a 32 amp MCB.

This paper talks about the problems with extra insulation. and I can see how even 6 mm² is really too small. Yes, I know one would need to take a very long shower for there to be a problem, but all it takes is a phone call, for a shower to be left on.

I can see both sides for code C1 and code C2, personally I would code it as code C2, as any codes C1 need addressing immediately, which gives just one option, disconnect it. Code C2 gives 28 days to correct it. So 8 kW = 35 amp, so in the main a 32 amp MCB will hold for long enough to have a shower, but the next size down is 25 amps, or 5.7 kW, and it is unlikely even a 7.5 kW shower (32 amp) will hold long enough to complete one's shower.

As to 7/0.036 in old money, this was 4.52mm² seems most the old sizes were slightly larger, so would have been OK for around 30.5 amp, so with a 30 amp fuse that would have been just within the limits. Fuse sizes were 30 amp not 32, so one can see how mistakes were made, and I could not tell be looking if a cable is 7/0.036 or 4mm² what about you?

 

[SUNRAY]

Does that really qualify as "C1" ?

Having encountered many 10.KW showers on B32's or 30 or 35A fuses and 4.0mm² cable which seem to be running correctly without any apparent damage, then no I don't believe it's a C1, in fact when there really is no damage I could almost see the justification for a C3. However I think it's fair to say they have only seen them as C1's

The biggest cause for concern according to the damage I've encountered is the 30A pullswitch which heats and bakes the wiring.

I had this in one of my rental properties where a tenant had changed a shower unit and going in for an EICR actually pulled the inspector part way in and we went back some days later to replace the cable and CU (from plastic CU in the porch by only external door) so there was never actually any codes on the EICR.

 

[JohnW2]

Having encountered many 10.KW showers on B32's or 30 or 35A fuses and 4.0mm² cable which seem to be running correctly without any apparent damage, then no I don't believe it's a C1, in fact when there really is no damage I could almost see the justification for a C3. However I think it's fair to say they have only seen them as C1's

You've moved the goalpost slightly, by now talking about 10.5 kw Showers and 4mm² cable "protected by B32s or 30/35A fuses", but, even in that situation, I personally still cannot see how it could possibly qualify as C1, and might well struggle to regard it as C2 - as you say, C3 might be appropriate.

"10.5 kW" showers are invariably 10.5 kW at 240 V, which equates to about 41.9 A at 230V

Method C 4mm² T+E has a CCC of 37A. It would be deemed to be 'safe' if it were protected by a hypothetical 37A MCB, and by virtue of the spec of such devices, that means that the cable would be deemed to be 'safe' (come to no harm) with a continuous current 'for ever' of about 41.8 A, and 'safe'with a current of about 53,6 A flowing for an hour.

The situation you describe would, strictly speaking, be non-compliant with BS7671 on at least two counts (ib>In and In>Iz), which might well be considered to justify a C3 - but, in view of what I've written in the previous paragraph, I would not personally regard the situation you describe as even 'potentially dangerous' - so not even a C2, let alone C1

 

[JohnW2]

I can see both sides for code C1 and code C2, personally I would code it as code C2, as any codes C1 need addressing immediately.... . So 8 kW = 35 amp, so in the main a 32 amp MCB will hold for long enough to have a shower, but the next size down is 25 amps, or 5.7 kW, and it is unlikely even a 7.5 kW shower (32 amp) will hold long enough to complete one's shower.cable 'at any danger' - since, as I recently wrote, it is deemed to be able to carry about 41.

Per what I've just written to Sunray, do you really believe that any of the scenarios being discussed constitute a "potential danger", hence deserving even a C2 (let alone a C1 !).

What do you thing is "put at danger"?? A 10.5 kW shower draws about 41.9 A at 230V and that current is certainly not going to put 4mm² cable 'in any danger' - as I've recently written, such cable (Method C) is deemed to come to no harm with about 41.8 A flowing indefinitely, and about 53.6 A for an hour. What 'danger' did you have in mind?

 

[SUNRAY]

As to a combi boiler even more problems, the Bosch on in parent's house had two options, eco off or on. With the eco off, the shower worked OK, but with eco on, the shower would start cold, get hot, then go cold again, then finally hot again. But, with eco off using all other taps they had to be full on, or the boiler would not fire up.

Bear in mind this ECO system cycling aimlessly around the random settings is potentially running at peaks of something like 25KWh of gas power.

Within that 3 minutes of mind numbing boredom waiting to be able to get under the water I've had my 2 minute shower and most of the way towards being dry using my 10.5KW instant electric heater running at low (2/3) power setting.

 

[SUNRAY]

You've moved the goalpost slightly, by now talking about 10.5 kw Showers and 4mm² cable "protected by B32s or 30/35A fuses", but, even in that situation, I personally still cannot see how it could possibly qualify as C1, and might well struggle to regard it as C2 - as you say, C3 might be appropriate.

"10.5 kW" showers are invariably 10.5 kW at 240 V, which equates to about 41.9 A at 230V

Method C 4mm² T+E has a CCC of 37A. It would be deemed to be 'safe' if it were protected by a hypothetical 37A MCB, and by virtue of the spec of such devices, that means that the cable would be deemed to be 'safe' (come to no harm) with a continuous current 'for ever' of about 41.8 A, and 'safe'with a current of about 53,6 A flowing for an hour.

The situation you describe would, strictly speaking, be non-compliant with BS7671 on at least two counts (ib>In and In>Iz), which might well be considered to justify a C3 - but, in view of what I've written in the previous paragraph, I would not personally regard the situation you describe as even 'potentially dangerous' - so not even a C2, let alone C1

I haven't moved anything, the thread had moved to showers on 4mm² cable, further I'm basically saying the same thing as you. Sadly the opinions of the EICR inspectors is generally based on a work generation scheme and marking something as C1 is more likely to result in additional profit than marking as C3

 

[JohnW2]

I haven't moved anything, the thread had moved to showers on 4mm² cable ...

It did but, if I recall correctly, not with any mention of the rating of the circuit's protective device.

However, it doesn't really make much difference to what I have said. If the circuit were protected by, say, a 40 A OPD, the (modest) non-compliances would be slightly different, but my bottom-line view would be unchanged - that to have a load of about 41.9 A fed via 4mm² (Method C) cable (with any OPD) is not going to introduce any significant 'potential danger' - hence, to my humble mind, not even C2, let alone C1

, further I'm basically saying the same thing as you. Sadly the opinions of the EICR inspectors is generally based on a work generation scheme and marking something as C1 is more likely to result in additional profit than marking as C3

As you say (and as above) we seem to basically agree. If they could not reasonably justify the C1 (and, as above, I can't see how they could), and if the CI were given for the reason you suggest, then might that not be a criminal offence, since it sounds like 'fraud' to me ?

 

[ericmark]

I had some problems with my dad's house, the pre-mm² cable was fine, but it showed the post mm² in this case 2.5 mm² had part melted, it was a spur from a spur, but location tells me likely prolonged use of a 3 kW electric fire, plus clearly something else. When I look at the loading of automobile cable, household cable is a lot lower, but the bunching of cables seemed to dissipate the heat, rather than cause over heating.

As to danger, one would hope a melted cable would trip something before it caused a shock risk, but what about fire risk? For a home with no insulation on the cable run, a 32 amp overload on a 4 mm² cable is likely safe enough. But can one be sure there is no insulation? My old house had cables in the cavity, and I know I instructed the people doing the cavity wall insulation to miss the area where the cables ran. But can one be 100% sure they have missed it?

This house I don't have a clue where the cables run, so not a clue if in insulation or not.

 

[SUNRAY]

It did but, if I recall correctly, not with any mention of the rating of the circuit's protective device.

However, it doesn't really make much difference to what I have said. If the circuit were protected by, say, a 40 A OPD, the (modest) non-compliances would be slightly different, but my bottom-line view would be unchanged - that to have a load of about 41.9 A fed via 4mm² (Method C) cable (with any OPD) is not going to introduce any significant 'potential danger' - hence, to my humble mind, not even C2, let alone C1

As you say (and as above) we seem to basically agree. If they could not reasonably justify the C1 (and, as above, I can't see how they could), and if the CI were given for the reason you suggest, then might that not be a criminal offence, since it sounds like 'fraud' to me ?

Although I agree with this, there are no strict rules on the definitions and as everything is referenced to something which in iself has no legal standing the whole thing is on a sticky wicket.

A cable running at ~120% of its absolute loaded rating (many areas are still >240V) is an overheating risk and therefore potentially a hazard risk. At those sorts of operating conditions it doesn't take very much for something to go wrong; a disturbed connexion or some insulation added or moved etc. to move from getting very warm to "Why didn't the inspector find that on the EICR" and then the considerations on whether it's easier to defend negligence or fraud to the man wearing a wig.

Having seen and worked on overloaded cables myself, I can see why some (many) will in their opinion class them as C1.