EICR on a Sunday

[vxwestie]

Is there a requirement to remove 90% of fittings on an EICR or go into a loft space?

Ive never earnt an extra penny for working on a Sunday either... Lol

 

[sparksburnout]

The job I mentioned above the bloke is some kind of air-con installer and apparently they always use 2.5mm for 3kw loads!

Pedantic as ever Dave eh? I think you will find 2.5 is extremely common for immersion flexes, FFS how much more does it cost to install a cable that is well over capacity for the load rather than one which is only just over. If I came across a plumber who stuck a bit of 1.5 in I would ask why as well.

 

[davesparks]

Pedantic as ever Dave eh? I think you will find 2.5 is extremely common for immersion flexes, FFS how much more does it cost to install a cable that is well over capacity for the load rather than one which is only just over. If I came across a plumber who stuck a bit of 1.5 in I would ask why as well.

Cost is irrelevant. If 2.5mm is squeezed into a terminal designed for a max of 1.5mm then there is a problem.
Do you also install all final circuits in bigger cable for the sake of putting an over capacity cable in?

I installed a ring final in 1.5mm at the weekend as that is what my calculations said would be right, would you have done it in 2.5 and wasted the extra couple of hundred pounds?

 

[sparksburnout]

Cost is irrelevant. If 2.5mm is squeezed into a terminal designed for a max of 1.5mm then there is a problem.
Do you also install all final circuits in bigger cable for the sake of putting an over capacity cable in?

I installed a ring final in 1.5mm at the weekend as that is what my calculations said would be right, would you have done it in 2.5 and wasted the extra couple of hundred pounds?

How many immersion heater heads are designed for 1.5mm? why would you install an RFC in 1.5 was it for a specific application or for general use, RFC's are usually installed in 2.5 as far as I am aware I cant really understand the point you are tying to make??

 

[sparkstu]

Pedantic as ever Dave eh? I think you will find 2.5 is extremely common for immersion flexes, FFS how much more does it cost to install a cable that is well over capacity for the load rather than one which is only just over. If I came across a plumber who stuck a bit of 1.5 in I would ask why as well.

Why would you ask why to a bit of 1.5 butyal? I never find 2.5 it's always been 1.5 and that's all I've ever done for standard immersion heaters why use anything else

 

[sparksburnout]

Why would you ask why to a bit of 1.5 butyal? I never find 2.5 it's always been 1.5 and that's all I've ever done for standard immersion heaters why use anything else

So that you don't find them suffering from overheating and general degrading over time, given the arduous environments they are often in. If you are running them off an FCU then that's a bad idea anyway as the fuse is at its limit and contributing to the overheating. How much more does a bit of 2.5 cost?

 

[sparkstu]

2.5 butyal rated at a higher temp then 1.5? Don't think so! As Dave has already said cost is irrelavant

 

[sparksburnout]

2.5 butyal rated at a higher temp then 1.5? Don't think so! As Dave has already said cost is irrelavant

Who said anything about the temperature rating?? 1.5 is rated at 16A, which, given the conditions it is being used in, is running it close. Have you not come across such cables in a bad state after prolonged use? And what's butyal anyway, it is like butyl?

 

[davesparks]

How many immersion heater heads are designed for 1.5mm? why would you install an RFC in 1.5 was it for a specific application or for general use, RFC's are usually installed in 2.5 as far as I am aware I cant really understand the point you are tying to make??

As far as I know the standard single phase 3kW immersion is designed for 1.5mm fix, and the cable grip certainly ain't big enough for any bigger flex.
I installed in 1.5mm because it was the right size for the job and I don't suffer from the urge to oversize the cables unnecessarily.
RFCs are subject to a minimum cable size of 2.5 for plastic insulated cables and 1.5 for mineral insulated cables though it is usual to install in 4mm single commercially to meet grouping requirements.

 

[davesparks]

Who said anything about the temperature rating?? 1.5 is rated at 16A, which, given the conditions it is being used in, is running it close. Have you not come across such cables in a bad state after prolonged use? And what's butyal anyway, it is like butyl?

You mentioned general overheating and degradation which in my experience is almost always down to the temperature affecting the insulation inside the terminal chamber of the immersion heater. I have never seen a 1.5mm butyl feeding an immersion heater suffer from overheating through overload.
localised heating at the terminations does not necessarily indicate overload or 'running it close', heating through overload is normally visible as a deformation of the insulation and sheath along the length of the cable or localised at bends or other stress points along the run of the cable.

A 3kW 240V immersion heater (2.7kW at 230V) which is the standard these days will draw 12.5A. this is just under 80% of the rated operating current of the cable (16A) I don't see how you can consider that to be running it close? It is only 4/5 of the rated current of the cable!

 

[Wonderwall]

I simply tell the customer they are paying for a report, as I find it. I leave it fully confident that they can get another sparky in if they wish to verify any faults I have highlighted.

 

[Andy78]

I fitted 3 lengths of 2.5mm butyl flex to immersion heaters yesterday. I'll let myself off over sizing the cable though as they were 4kW elements. Now that would have been pushing 1.5mm flex to its limit, but a 3kW element certainly wouldn't.

 

[Lucien Nunes]

I don't see how you can consider that to be running it close? It is only 4/5 of the rated current of the cable

Indeed. For anyone worried about using a cable near rating, remember that the heat dissipated is proportional to the square of the current, in this case 16/25 or about 64% of the permitted temperature rise.

I can see the point in standardising on 2.5 for 3kW aircon loads though as the voltage drop during compressor starting is critical and might often be a more onerous requirement than CCC.

 

[Skimpy Wan]

Indeed. For anyone worried about using a cable near rating, remember that the heat dissipated is proportional to the square of the current, in this case 16/25 or about 64% of the permitted temperature rise.

Please can you explain this one to me as I've not heard / been taught this calculation / consideration .... sorry if I'm being dumb!

p.s.Can we not just say heat resistant flex rather than butyl ... its so much easier to spell!!:tounge_smile:

 

[Andy78]

Please can you explain this one to me as I've not heard / been taught this calculation / consideration .... sorry if I'm being dumb!

p.s.Can we not just say heat resistant flex rather than butyl ... its so much easier to spell!!:tounge_smile:

Butyl has enhanced heat resistance over standard duty flex, but not all heat resistant flex is butyl. Butyl is rubber HR flex but you can get PVC HR flex too.

 

[Lucien Nunes]

Please can you explain this one to me

P=I²R

This P being the one dissipated in the cable, not the load.

 

[Skimpy Wan]

Cheers.

I now need to learn to spell butyl correctly then! Lol! Only every used "heat resistant flex" from wholesalers. I'll have a look into when butyl would be prudent in comparison to heat res. flex.

I didn't notice the link between P = I2 x R, so thanks for clarifying for me