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Topic Title: Immersion Heater Supply Question.
Topic Summary: Opinions Invited Please.
Created On: 04 August 2017 04:56 PM
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 13 August 2017 01:11 PM
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geoffsd

Posts: 1702
Joined: 15 June 2010

But the ridiculous Table 52.3 allows 0.75 sq.mm. for:

any other application

and even smaller for:

specific appliances if specified in the product standard.

 13 August 2017 10:12 PM
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AJJewsbury

Posts: 15812
Joined: 13 August 2003

Oh good. I know in the past you have been of the opinion that the output of a fused connection unit was a circuit. I thought for a minute you were going down the line of the fused spur constituting a circuit and therefore as its heating not lighting, the minimum size cable was 1.5mm!

Oh it's definitely part of a circuit (whether after a FCU or not) - it can be 0.75mm2 though, 'cos it's flex - not solid or (course) stranded (although I can't vouch for the reasoning for that).
- Andy.
 14 August 2017 08:23 AM
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Zoomup

Posts: 3266
Joined: 20 February 2014

Originally posted by: weirdbeard

Hi zoomup, it's any help I don't think you did anything wrong by fitting your 16A MCB in the airing cupboard, it's not like it's cost the customer loads and I'm sure you did a fine job, but as mentioned in post 2 of this topic and by others, a 20A switch would be fine.



I'd always put money on any airing cupboard fire being caused by a faulty plastic timer. It might reduce fires those timers were only used as a switching device for a nice clunky contactor?


Yes weirdbeard the cheap plastic timers are of poor quality and probably more suitable for small items like security lights in the house.

The Horstmann Economy 7 Quartz timers are so much better for immersion heater control, but cost a lot more than the cheap plastic ones.

Bye,

Z.
 14 August 2017 09:41 PM
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Zs

Posts: 3814
Joined: 20 July 2006

Well, I disappear with my broken heart and new job to settle in to without them knowing about that bit. House being cleared out whilst at work kind of thing. Half a bottle of Tennessee Honey, a few days...and I miss this thread. I don't half wish I'd had my eye on it but oh well. OMS alerted me to it last night (he driving too far in the cause of work, me wondering if the mattress on the floor is OK for a grown-up cos I quite like it there) and so on.

I had no idea how many posts OMS was referring to so I've scanned and not fully read. But things are coming to mind as I read through;

First. That the switch in an airing cupboard, when it energises, often causes a visible spark. If I have seen one I have seen fifty. Trust me I have seen. No question, visible or not, there is a burst on energising. Over time I have no doubt that this spark or burst of heat will cause degradation and quite possibly the issue the Zoomup alerted us to in the opening.

Things have a shelf life and maintenance is required. As Pete TLM says in his tag; ' Lack of planning on your part does not make it an emergency on mine'. Any designer worth their salt will produce a document about the life expectancy of an installation. In domestic that is quite a different matter.

Then, that the ambient temperature in an airing cupboard is about 24 degrees when the tank is at its warmest. I know that because mine is measured with a super little device from Ikea. That is not going to cause degradation in the extreme ways to which some have referred...IMO.

Then Dave Z's post of 6th August;

Originally posted by: davezawadi

It seems that we are back to attempting to foresee the future again, and imagining extremely unlikely faults. The fault scenario suggested by Z is extremely unlikely and probably not possible due to the heater construction. Leakage from heater elements to the sheath does happen, but this is milliamps not 32A. .


The entire post fantastic and erudite. The above is just a snippet of what I think is a fine post.

I worry that we are on the edge of causing yet another regulation to be written.

Talking of the future... I've gone back. I stood in front of a machine that soo looks like the flux capacitor that I had to pinch myself. But it is real and you'd love it. But the pack mentality, sexism ( genuinely, I never thought I'd hear myself saying that word in relation to myself) and bullying are jaw-dropping and they don't even realise they are doing it.

I might be a touch busy for a little while eh? Got a flux capacitor to fix......

Please don't make another reg for the 18th, there is enough in there that needs comment as it is.

Zs
 14 August 2017 10:44 PM
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alancapon

Posts: 6879
Joined: 27 December 2005

Originally posted by: Zs
. . . the ambient temperature in an airing cupboard is about 24 degrees when the tank is at its warmest. . .

Remember also that if you are using the immersion heater, a BS1362 fuse operating at its maximum capacity may dissipate up to 1 watt of heat. In the case of an FCU, this will act as a heat source inside the accessory.

Regards,

Alan.
 15 August 2017 09:44 PM
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Zs

Posts: 3814
Joined: 20 July 2006

Yes Alan, I reckon much like a plug feeling warm.

Being a regular user of a hairdryer I also observe that toward the end of their useful life, hairdryers run very hot for a month or two. A sign of imminent failure to me. If this is also true of other heating elements (?) such as immersion heaters then Zoomup's issue may be explained by the age of it.

Perhaps just a life expectancy/ replacement date like in smoke alarms?

Zs
 15 August 2017 11:21 PM
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potential

Posts: 1630
Joined: 01 February 2007

Originally posted by: Zs
Yes Alan, I reckon much like a plug feeling warm.
Being a regular user of a hairdryer I also observe that toward the end of their useful life, hairdryers run very hot for a month or two. A sign of imminent failure to me. If this is also true of other heating elements (?) such as immersion heaters then Zoomup's issue may be explained by the age of it.
Perhaps just a life expectancy/ replacement date like in smoke alarms?
Zs

IME hair dryers get hotter as they get more bunged up with hair.
Every year or so my wife will complain about our hair dryer and almost without exception it is hair causing the problem. .

And why do so many people roll up the flex so tightly on small appliances?
It is as if they tying the moorings for the QE2.
I've had to replace the flex on the dryer at least 3 times in the 34 years we have had it.
 16 August 2017 08:10 AM
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leckie

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Joined: 21 November 2008

Your spoiling that lady!
 16 August 2017 02:01 PM
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Zoomup

Posts: 3266
Joined: 20 February 2014

Another example of an airing cupboard fire. http://www.fenlandcitizen.co.u...-fire-1-2340752


An elderly couple suspected "smouldering" in the airing cupboard. "The fire had smouldered undetected in the airing cupboard while the elderly residents searched for the reason their fire alarm was going off."





Z.
 16 August 2017 02:08 PM
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Zoomup

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Airing cupboards high fire risk. http://books.google.co.uk/book...g%20cupboards&f=false

Z.
 16 August 2017 02:08 PM
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Zoomup

Posts: 3266
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Airing cupboards high fire risk. http://books.google.co.uk/book...g%20cupboards&f=false

Z.
 16 August 2017 02:18 PM
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Zoomup

Posts: 3266
Joined: 20 February 2014

Cotton tea towels start airing cubboard fire by self ignition/self combustion. http://www.standard.co.uk/news...t-london-a2945331.html

The brigade's Charlie Pugsley said: "Cotton laundry like aprons, tea towels and cloths can often be contaminated with organic cooking oils that can self-ignite if dried and stored.

Z.

Edited: 16 August 2017 at 02:43 PM by Zoomup
 16 August 2017 02:23 PM
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Zoomup

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Sorry about the double entry above. Technical reasons prevent deletion of one.

Z.
 16 August 2017 02:26 PM
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Zoomup

Posts: 3266
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Yet another airing cupboard fire report. http://www.bbc.co.uk/news/uk-england-norfolk-35779975

Z.
 16 August 2017 02:36 PM
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Zoomup

Posts: 3266
Joined: 20 February 2014

Another Charlie Pugsley report about spontaneous fires of tea clothes etc. [L=http://www.telegraph.co.uk/new...rsts-into-flames.html
http://www.telegraph.co.uk/news/uknews/11859718/Fire-brigade-issues-warning-after-too-hot-laundry-spontaneously-combusts-and-bursts-into-flames.html

"Natural fibres such as cotton are susceptible to spontaneous heating and subsequent spontaneous combustion. However the possibility of residual materials such as cooking oils or cleaning products can increase the likelihood of fire."

Z.
 16 August 2017 02:53 PM
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Zoomup

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A terrible story is contained here about a dementia victim who had an airing cupboard fire. http://www.alz.co.uk/sites/def...cal-lessons.pdf


"....the lady with dementia whose family had put signage up on the front
door, because she used to go out and wander. And she had the fire
in the airing cupboard, and she walked past the fire, and went
downstairs, and because she knew she shouldn't go out the front
door, she went and sat in the front room. But all the doors were
open, so she died from smoke inhalation... there were signs on the
door, and the family told the Fire Investigation Officer, that because
she had a habit of going out and wandering, and the police kept
bringing her home, and they kept getting phonecalls at three or four
o'clock in the morning, there was a sign on the front door, that said,
don't go out of the door. So, she didn't. G1F4."


Z.
 16 August 2017 03:20 PM
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Zoomup

Posts: 3266
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An report of the spontaneous combustion of a pile of towels. Could this happen in an airing cupboard?

http://www.skynews.com.au/cult...neously-combust-.html

Z.
 17 August 2017 12:02 PM
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chrisbradley

Posts: 79
Joined: 13 September 2005

I think this particular thread's run out of steam at this point......but following comments received at moderator level, I'm going to lock this one here. Thanks all....!

Chris
IET » Wiring and the regulations » Immersion Heater Supply Question.

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