Author Topic: Quite nervous doing this...  (Read 2441 times)

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Offline paulca

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Quite nervous doing this...
« on: January 23, 2020, 07:39:21 pm »
So my house has loads of underfloor "ventilation".  The meter cupboard had bare floor and was allowing cold air in.  Literally it was like 5*C in there at night time and cold air pouring in so much that if you open a window the meter cupboard door would blow open.

So I decided to put thermal underlay down to cover all the cracks and holes.

Thing is... it has a conductive upper layer!  No point turning the power off either.  Just had to nervously make sure it didn't hit anything.  I don't think there is any exposed live, but it was still a bit daunting.

Of course I did bump the trip test button and it's got such a heavy spring on it, it went CRACK! and darkness.  Scared the living sh1t out of me.

Done now though, phew!

"What could possibly go wrong?"
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Offline andy3055

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Re: Quite nervous doing this...
« Reply #1 on: January 23, 2020, 09:07:50 pm »
That looks pretty dangerous and could be against the local code!

You could line the floor with plywood instead and seal off all the edges with silicone sealant - the kind used for sealing bathroom sinks. For better insulation, line up foam sheets under the plywood.

Just my thoughts.
 

Offline thinkfat

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Re: Quite nervous doing this...
« Reply #2 on: January 23, 2020, 09:36:15 pm »
What on earth is THAT? Your house mains wiring??
 

Offline dmills

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Re: Quite nervous doing this...
« Reply #3 on: January 23, 2020, 09:45:41 pm »
Yup, older style UK incomer, meter, RCD and breaker box, not the neatest job I have seen but fairly typical of what you find in older housing stock, and FAR from the worst job you will see.

Current rules would need non flammable materials and a metal cased breaker box, but you only got to make those changes if doing major work.

Regards, Dan.
 

Online Ed.Kloonk

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Re: Quite nervous doing this...
« Reply #4 on: January 24, 2020, 12:55:14 am »
What on earth is THAT? Your house mains wiring??

Nice timber backboard. Classy.  :-+
 

Offline TerraHertz

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Re: Quite nervous doing this...
« Reply #5 on: January 24, 2020, 04:59:12 am »
So that's just some lightweight foam with a foil layer, sitting there unattached?
Won't make any difference. If air draft came up through gaps in the floorboards before, it still will. And lift that foam up like a piston.

I'm guessing that 'solution' was chosen because you don't have any means of cutting to shape something solid, like plywood?

How about this instead: Some old heavy felt carpet underlay, with a layer of something like linoleum or rubber floor matting on top. Those are all things that can be cut with scissors. Then seal any gaps around the edges with silastic. But if you cut the underfelt a bit oversize that won't be necessary.

End result: a relatively non-flamable, electrically insulating layer, heavy enough to hold down against draught pressure.

Or, just seal all the floorboard gaps with gap-filler.
« Last Edit: January 24, 2020, 05:01:43 am by TerraHertz »
Collecting old scopes, logic analyzers, and unfinished projects. http://everist.org
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #6 on: January 24, 2020, 08:21:42 am »
So that's just some lightweight foam with a foil layer, sitting there unattached?
Won't make any difference. If air draft came up through gaps in the floorboards before, it still will. And lift that foam up like a piston.

Yes, it's regulation compliant foam underlay for putting under hardwood flooring.  I believe it's fire retardant.  The upper layer is mica or something, probably not actually conductive on it's surface as it's laminated in plastic.

I weighted it down with stuff.  But, yes the air still gets round it and I can still feel a draft under the door. 

I might just seal the door surround.

On my meter box.  This is a late 1960s house.  Looks like the meter box has been updated maybe 10 years ago.  Not sure if house has been rewired, but it is using black/red twin and earth and has way too many double plugs for a 1960s house.  However it's still out of date, if it was rewired it was 10 or 20 years ago.

A rewire is on the long finger, but at approximately £3000 it will need to wait for other work first.
"What could possibly go wrong?"
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Offline BillyD

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Re: Quite nervous doing this...
« Reply #7 on: January 24, 2020, 09:25:01 am »
I imagine it should at least reduce air flow through the floor of that compartment which should be some help.
Just wondering about the boards that the electrics are mounted on, could there also be draughts coming through the gaps in these boards and around the edges, etc.
Assuming that the door the cupboard doesn't get opened very often, it might be more effective to tackle the cupboard door - put a good seal around it, a latch to ensure it doesn't spring open, maybe even insulate it.

 

Online janoc

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Re: Quite nervous doing this...
« Reply #8 on: January 24, 2020, 10:59:21 am »
Hum, if anything goes wrong in that closet, you have at least a well prepared electrocution chamber now. You feeling nervous about doing this is a pretty good indication that it is a terrible idea.

Sealing the holes and cracks with either silicone or foam is a much better (and safer) way.
 

Online ebastler

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Re: Quite nervous doing this...
« Reply #9 on: January 24, 2020, 01:41:19 pm »
Looking at your original post, I had not realized that you meant that to be the complete job!?!  :wtf:  As you state, this stuff is meant to go underneath hardwood floor. Please do yourself a favor and put something on top of it — pine board, cheap laminate, whatever.
 

Offline CJay

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Re: Quite nervous doing this...
« Reply #10 on: January 24, 2020, 02:02:41 pm »
I think perhaps I'd look around for some PIR board without foil. Or fit draught strip around the door to the meter cupboard and find a decent latch.
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #11 on: January 24, 2020, 02:57:11 pm »
Yes, I'm currently considering laying heavy underfelt over it and putting a draft strip around the door.  It doesn't have to be pretty, it's an under stairs cupboard.

Also I think the "foil" is just metalized plastic sheet, it's probably only 1 or 2 atoms of aluinium thick to create the thermal mirroring.
"What could possibly go wrong?"
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Online TK

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Re: Quite nervous doing this...
« Reply #12 on: January 24, 2020, 03:12:53 pm »
Yes, I'm currently considering laying heavy underfelt over it and putting a draft strip around the door.  It doesn't have to be pretty, it's an under stairs cupboard.

Also I think the "foil" is just metalized plastic sheet, it's probably only 1 or 2 atoms of aluinium thick to create the thermal mirroring.
:palm:
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #13 on: January 24, 2020, 03:48:10 pm »
Yes, I'm currently considering laying heavy underfelt over it and putting a draft strip around the door.  It doesn't have to be pretty, it's an under stairs cupboard.

Also I think the "foil" is just metalized plastic sheet, it's probably only 1 or 2 atoms of aluinium thick to create the thermal mirroring.
:palm:

You know how mirroring of surfaces works in the modern world and how they can use silver to coat mirrors and not have it cost thousands?  They vapourise the metal (or metal compound) and allow it to condense onto the electrically charged surface forming a layer with is literally only a few atoms thick but creates a perfect mirror effect.

Even electroplating can be done to produce extremely thin layers.  Food packaging with "foil" is quite often actually plastic with an extremely thin layer of metal to make it look like foil. Crisp packets for example.
"What could possibly go wrong?"
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Online Monkeh

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Re: Quite nervous doing this...
« Reply #14 on: January 24, 2020, 03:52:59 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?
 

Offline Twoflower

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Re: Quite nervous doing this...
« Reply #15 on: January 24, 2020, 04:05:29 pm »
A telescope mirror has a coating about 100nm a diameter of an Al atom is about 125pm. So I think that's a bit more than 1 or two atoms.

An Al is cheap, so even a 1mm layer wouldn't cost a fortune compared to the whole thing.

If interested spend some time watching this (Recoating a Giant VLT Mirror):
 

Offline NivagSwerdna

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Re: Quite nervous doing this...
« Reply #16 on: January 24, 2020, 04:07:04 pm »
An isolation switch just after the meter.  That's quite novel?
 

Offline andy3055

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Re: Quite nervous doing this...
« Reply #17 on: January 24, 2020, 04:11:39 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?

The problem is what he has done. We are not addressing the cables in this post.
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #18 on: January 24, 2020, 04:33:06 pm »
An isolation switch just after the meter.  That's quite novel?

As I understand it, this is common.  It is also a requirement in some houses depending on the type of earthing.

If you are replacing a consumer unit/breaker board in a house you need to disconnect the mains, however the main inlet in the UK is usually sealed with metal seals and you are not allowed to break the seals.  Breaking the seals is considered "tampering with ultility equipment" and a criminal offense, since you could have been installing a meter bypass loop, yes that's a thing! Some areas it's just a matter of calling up the distributor and getting authorisation to cut the seals and pull the main fuse, in others it requires the distributor send out an engineer to do it.  Either way the distributor has to come back out to replace the seals later.  All this costs money and time.

So in a lot of places a sensible spark will install some form of 80/100A isolator between the meter and the consumer unit making it easier in future to isolate the board to do work on it.
"What could possibly go wrong?"
Current Open Projects:  3 Channel Audio mixer with DAC, BT, pre-amps and h/phone amp, WS281x LED controller Version 2 5V/5A w/Atmega328, FY6600 Power supply, 5A DC Load (Still!)
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #19 on: January 24, 2020, 04:43:06 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?
The problem is what he has done. We are not addressing the cables in this post.

His point is, there is no exposed mains.  As discussed elsewhere, (a) the flooring is not actually conductive in it's current state (I can test that) and (b) it should/will be covered with something else.

"What could possibly go wrong?"
Current Open Projects:  3 Channel Audio mixer with DAC, BT, pre-amps and h/phone amp, WS281x LED controller Version 2 5V/5A w/Atmega328, FY6600 Power supply, 5A DC Load (Still!)
 

Offline NivagSwerdna

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Re: Quite nervous doing this...
« Reply #20 on: January 24, 2020, 04:51:24 pm »
So in a lot of places a sensible spark will install some form of 80/100A isolator between the meter and the consumer unit making it easier in future to isolate the board to do work on it.
Indeed. I'm a bit jealous. I'm pretty sure my consumer unit cannot be isolated without pulling out the company fuse.
 

Online Monkeh

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Re: Quite nervous doing this...
« Reply #21 on: January 24, 2020, 05:59:42 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?

The problem is what he has done. We are not addressing the cables in this post.

... and what is it he's done? Placed an object next to a cable?
 

Offline paulca

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Re: Quite nervous doing this...
« Reply #22 on: January 24, 2020, 07:32:38 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?

The problem is what he has done. We are not addressing the cables in this post.

... and what is it he's done? Placed an object next to a cable?

It's a lot more funny if you think about all the things that you would normally find in the understairs cupboards.  Examples:

The hoover.
Your wellie boots.
The kids wellie boots.
The tent.
Camping gear.
The boxes of biscuits from Christmas that nobody likes.
Your sons first bike that he's well outgrown but you still keep in case you have another kid.
The ironing board.
The spare car battery.
Engine oil / washer fluid.
Shovel for the drive and car window scraper.
Your old HiFi the wife hated.

Usually it's piled so high that to read the meter you need to pull a load of junk out first.

It used to be a favourite place to play hide and seek when I was a kid.
"What could possibly go wrong?"
Current Open Projects:  3 Channel Audio mixer with DAC, BT, pre-amps and h/phone amp, WS281x LED controller Version 2 5V/5A w/Atmega328, FY6600 Power supply, 5A DC Load (Still!)
 

Offline Bud

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Re: Quite nervous doing this...
« Reply #23 on: January 24, 2020, 07:46:21 pm »
Your sons first bike that he's well outgrown but you still keep in case you have another kid.
Usually that goes along with your sons carseat that was hoarded before the bike  :-DD
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Online coppice

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Re: Quite nervous doing this...
« Reply #24 on: January 24, 2020, 07:57:20 pm »
That looks pretty dangerous and could be against the local code!

?!

Double insulated cabling, what's the problem?

The problem is what he has done. We are not addressing the cables in this post.

... and what is it he's done? Placed an object next to a cable?

It's a lot more funny if you think about all the things that you would normally find in the understairs cupboards.  Examples:

The hoover.
Your wellie boots.
The kids wellie boots.
The tent.
Camping gear.
The boxes of biscuits from Christmas that nobody likes.
Your sons first bike that he's well outgrown but you still keep in case you have another kid.
The ironing board.
The spare car battery.
Engine oil / washer fluid.
Shovel for the drive and car window scraper.
Your old HiFi the wife hated.

Usually it's piled so high that to read the meter you need to pull a load of junk out first.

It used to be a favourite place to play hide and seek when I was a kid.
It amazes me people get away with this kind of thing as much as they do. The terminals on most meters, and some of the other items used for consumer wiring, are not well shielded, and its very easy for some piece of metal amongst the junk in a cupboard to poke into one of those recesses.
 


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