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Topic Title: Loft Insulation
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Created On: 18 November 2012 05:42 PM
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 18 November 2012 05:42 PM
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Avatar for MrOther.
MrOther

Posts: 528
Joined: 08 June 2010

Just had my house's loft reinsulated. Before workers came in I removed all the old insulation. Rewirde some of the old lighting cables as they were unclipped and tangled, spent last week's nights rewiring and reclipping cables where needed so there was no trip hazards. Junction Boxes were labelled (more for my benefit, bedrooms are being done up next year.)

Told my Mum and Dad - and made it clear that I didn't want my cables covered. Apparently -- Polish nodded that he understood and took the extra bit on top from my Dad.

Went up there today to find it all more or less covered. Seems like they squeezed some insulation inbetween the beams and then layered over the top with some more 300mm thick insulation for good measure. Must say the house feels warmer.

1) Is this normal practice -- to lay so much down?
2) In reality is a normal house lighting circuit going to be that much affected? Can't see it myself.
3) Can anyone point me in the direction of some good halogen guards to put over lights?
4) Any practical advice about making out where things are without ripping the insulation to pieces; or pulling all my nicely clipped cables up above insulation?

Many thanks again.
 18 November 2012 05:58 PM
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rocknroll

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Joined: 03 October 2005

This might help you;

http://electrical.theiet.org/w...-ratings.cfm?type=pdf

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 18 November 2012 06:58 PM
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alanblaby

Posts: 343
Joined: 09 March 2012

I'm just re-wiring a 1950's bungalow with around 18 inch of insulation. It is an awful job, but with a little help from the builders and plumbers on site, most of it has been chucked to one side until the work has finished.
As to cable ratings, I had intended to run the wires on cables trays attached to the joists, but, on reflection, that is far too much work, so have opted to clip to joists, de-rate the circuits, and add extra circuits, so power radials are in 2.5mm with 16A RCBOs, lights on 6A etc.
1.5mm T+E can run 13A continuous, clipped to a joist with over 100mm of insulation, so I wouldnt worry too much about the depth of insulation if yours is clipped.
The more insulation, the warmer the house will be.
As for getting at the wires in future - how often would that happen? Modern insulation isnt so irritating, so you will be able to roll it back if need be.
 18 November 2012 07:02 PM
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normcall

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I have a feeling that in order to get a grant for this work, the contractors have to ensure existing cables are laid on top of any insulation.
I confess I've yet to see it done and I just walk away from any job when you lift the loft trap and spot a sea of yellow and stupid signs that say be careful and use crawling boards.
Obviously it's much cheaper just to lay over everything existing from wiring to pipes to mouse droppings.

-------------------------
Norman
 18 November 2012 07:23 PM
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Avatar for Martynduerden.
Martynduerden

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Originally posted by: rocknroll

This might help you;



http://electrical.theiet.org/w...gs.cfm?type=pdf



regards


What about 1.5 & 1.0 mm?

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 18 November 2012 07:29 PM
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rocknroll

Posts: 8824
Joined: 03 October 2005

Paragraph 5 Page 2.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 18 November 2012 07:50 PM
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MrOther

Posts: 528
Joined: 08 June 2010

Originally posted by: normcall

I have a feeling that in order to get a grant for this work, the contractors have to ensure existing cables are laid on top of any insulation.

I confess I've yet to see it done and I just walk away from any job when you lift the loft trap and spot a sea of yellow and stupid signs that say be careful and use crawling boards.

Obviously it's much cheaper just to lay over everything existing from wiring to pipes to mouse droppings.


Hahha Norm this exactly has has happened. Sign too. Mum has just told me an inspector is due so we'll see and I'll report back.
 18 November 2012 07:53 PM
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MrOther

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Originally posted by: alanblaby

I'm just re-wiring a 1950's bungalow with around 18 inch of insulation. It is an awful job, but with a little help from the builders and plumbers on site, most of it has been chucked to one side until the work has finished.

As to cable ratings, I had intended to run the wires on cables trays attached to the joists, but, on reflection, that is far too much work, so have opted to clip to joists, de-rate the circuits, and add extra circuits, so power radials are in 2.5mm with 16A RCBOs, lights on 6A etc.

1.5mm T+E can run 13A continuous, clipped to a joist with over 100mm of insulation, so I wouldnt worry too much about the depth of insulation if yours is clipped.

The more insulation, the warmer the house will be.

As for getting at the wires in future - how often would that happen? Modern insulation isnt so irritating, so you will be able to roll it back if need be.


Thanks Al, yea that's how I figured, should be okay for 13A and any new lights in the house, bar those one on dimmers will more then like be LEDs.

RocknRoll I've saved that PDF nice one.
 18 November 2012 07:53 PM
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Avatar for MrOther.
MrOther

Posts: 528
Joined: 08 June 2010

Originally posted by: alanblaby

I'm just re-wiring a 1950's bungalow with around 18 inch of insulation. It is an awful job, but with a little help from the builders and plumbers on site, most of it has been chucked to one side until the work has finished.

As to cable ratings, I had intended to run the wires on cables trays attached to the joists, but, on reflection, that is far too much work, so have opted to clip to joists, de-rate the circuits, and add extra circuits, so power radials are in 2.5mm with 16A RCBOs, lights on 6A etc.

1.5mm T+E can run 13A continuous, clipped to a joist with over 100mm of insulation, so I wouldnt worry too much about the depth of insulation if yours is clipped.

The more insulation, the warmer the house will be.

As for getting at the wires in future - how often would that happen? Modern insulation isnt so irritating, so you will be able to roll it back if need be.


Thanks Al, yea that's how I figured, should be okay for 13A and any new lights in the house, bar those one on dimmers will more then like be LEDs.

RocknRoll I've saved that PDF nice one.
 18 November 2012 07:56 PM
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Avatar for MrOther.
MrOther

Posts: 528
Joined: 08 June 2010

Originally posted by: alanblaby

As to cable ratings, I had intended to run the wires on cables trays attached to the joists, but, on reflection, that is far too much work, so have opted to clip to joists, de-rate the circuits, and add extra circuits, so power radials are in 2.5mm with 16A RCBOs, lights on 6A etc.
.


How about a plane of wood spanning across and clip to that? Cheaper, can still look decent and saves have to lean over clipping to the side of joist.
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