Looking at buying Log Cabin.
Wiring slots already cut into beams/walls, therefore cables will be enclosed in wood when fed in.
Looking at regs T&E 2.5 should be OK BUT Building regs now say about using intumescent material in boxes to stop spread of Fire !.
What about cables should they be LSX type ?.
Seems to be a grey area.
Rgds.

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Helping others today enables
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A better description of the "logs", slots and type of boxes may help.

A did a "log cabin" it is rectangular squared timber sections tongued and grooved together with joints at the building corners so the walls ended up flat with v joints. So face fixed white surface mounted pattress boxes, cables clipped up walls with site made timber capping over them Installation method 8, 9 with a little bit of 12 table 4A2 page 317, so B possibly A, the juries still out as the IEC haven't made their mind up according to the foot note!

Intumescent material in boxes? Where are you stopping it spreading too?

Andy

422.4.102 only talks about cables complying with BS EN 60332-1-2 (cables under fire conditions) which according to one manufacturer at least ( http://www.prysmian.co.uk/expo...B/attach/pdf/6241Y.pdf ) their ordinary T&E does comply with.

There's always some debate about "low smoke/fume" cables with exact characteristics varying between manufacturers - but commonly although they may produce less harmful smoke, they're not necessarily less likely to catch fire (or even start a fire) and certainly aren't "fireproof".

Do you have a reference to the building regs requirement for intumescent back boxes?

- Andy.

Building Regulations
Document B of the Building Regulations stipulates the fire protection measures required for all building types. These regulatory requirements include timber framed buildings.

As the cables will be fully enclosed in wood.
The wooden walls are 125mm thick and when fiited together there is a slot already cut in them to feed cables up to roof area.
Owner then cuts box holes out as required.
This hole which is 25mm slot would then allow fire to spread up the hole to roof which is why intumescent material could be fitted to boxes to stop spread of fire.
BUT, there seems as I said a grey area about cables themselves !.
Any help folks ?.
Rgds.

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Helping others today enables
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So similar arrangement to installing on Paramount plasterboard partitions and Stramit straw ones, I assume you mean a cable route it drilled through rather than slotted into the face., I have never seen intumescent used on those systems, in fact it could be argued the same applied to studding on even capping nailed onto masonry as they can have a cable route running directly into a loft. I'll have to give that one a bit more thought.

There timber at 125mm is itself "fire rated" due to its thickness, what's the plan, make a template and use a router with a guide bush to machine out the timber allowing galvanised knock out boxes to be flush mounted.

Andy

"Building Regulations
Document B of the Building Regulations stipulates the fire protection measures required for all building types. These regulatory requirements include timber framed buildings."

I'm going to do a "yes, but" here.

In terms of the building regs I would take the reference to timber framed buildings to mean mean softwood framing, insulated panels or similar with a internal finish of plasterboard giving fire protection to the structural timbers, so if the plasterboard is pierce and a drylining box is inserted the fire resistance is compromised, so inclusion of a intumescent pad would solve the issues. However think also of a light fitting mounted on the ceiling, where the cables come through the plasterboard the hole should be filled in.


In this case it's some what different, the structural timber has its own fire resistance without the building having a plaster board lining and there isn't a void in the wall other than the cable slot. So I consider that a simple squib of mastic either intumesecent mastic or maybe even painters caulk into the end of the slot would probably meet the requirement of the building regs part B 7.24.4- fire stops particularly if there is a plaster board ceiling sat on top of the walls.

However I'd have expected to see the ceiling going up to the roof ridge line with a soffit of timber match board overlaid with a polythene vapour membrane, Kingspan type insulation slabs, plywood and felt tile strips or similar. So where you would define having a point to insert a fire stop is going to be open to debate, so maybe settle for a squib of intumescent mastic top and bottom of the slot.

Does that sound logical? I don't know if a building inspector will agree

Andy

Surely this is a single fire compartment?...

I'd say yes and the timber walls have a 30 minute fire rating without plasterboard internally.

You'll do all this worrying about the back boxes, then install a wood burner and get hot ashes all over the place.

Andy

The Cabin is slightly different to the wooden building structures in that it's "Solid Wood" I'm told Russian Spruce and comes from Estonia !.
So far the best bet seems to be "Intumescent Mastic" top & bottom of cable runs.
The boxes are metal let in to the wood, the buildings do appear quite impressive in that all log walls are marked on plan where to go so all holes/runs line-up.
Took four guys 2 Days to put up all walls and looks good approx 10 x 8Mtrs + Windows & doors.

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Helping others today enables
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Cheers Andy,
Strange thing is I believe my friend is going to put in a Wood Chip heater !.
These items are really very efficient, Iv'e seen a couple of them and they work really well.

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Helping others today enables
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Dare I say it is a posh garden shed!

80 sq m is more than the 15sq m allowed without planning permission as a general rule.

That should concentrate your mind.
Mine is 14.9 sq m and I wired it in plastic conduit

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Norman

Gordon, I do quite a few log cabins. I'm not sure where you get the intumescent requirement from, I only really know it from trunking and riser issues, but I applaud it. Intumescent puts out its own fire by swelling up around the heat... doesn't matter where it was trying to get to because the potential fire is gone once the intumescent has done its job.

Is it a big brand of log cabin you are considering? What are you going to be using it for? single or double skin and how thick?

They do take a while to wire, it is not like doing a shed so allow yourself some time for it. Consider a remote smoke alarm in the house if it is far away. ( and Shhh, but if you have kids who are going to use it as a den, an intercom to and from the house where you can quietly pick up the receiver in the house and listen might not be a bad thing.... you are going to have every parent in the neighbourhood phoning you to see if you have got their child round yours because log cabins are very cool places to be).

But in answer to your question, I use arctic cable if it is going underneath the cabin and is likely to be exposed to the elements, plastic conduit if I can install alongside the cabin builders. Otherwise, just normal stuff. It depends on what the cables are going to be asked to do. RCDs in extremis, and don't forget about mice and gliss-gliss. Do it once.
Zs

I don't crawl under the cabins to install wiring, that's where the Ducks live, so apart from cramped conditions you end up covered in Duck !"£$

Andy

As Paul has hinted above, the cabin is a single fire compartment, and no one else lives on the roof, or under it in a basement, and its not split into flats is it?
You can escape from it in under a minute even by fingernails.
Intumescent materials are to stop spread of fire from one fire compartment to another, often one flat or house to another which isnt valid in this situation.
LSF cables are used to stop acrid fumes from chocking everyone to death in the process of escaping a burning (often public) building, but you will be out in a minute so dont bother.....

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry

Information here if you want it;

http://www.planningportal.gov....rojects/outbuildings/

Part A Structural Stability - This may require structural calculations to demonstrate stability in situations of combined loadings such as winds and snow loads. Often log cabins are modular in design in there are type approvals in place to prove the strength of the individual modules or proof calculations exist for worst case scenario structures.

This section will also deal with the strength and stability of foundations. These will need to be designed with regard to site conditions and the loadings imposed by the building.

Part B Fire - For garden structures or log cabins this will only be relevant if there is an issue regarding closeness to boundaries or separation distance from other buildings. However this section will be very relevant in buildings that fall into dwelling or commercial classifications.

Part C Materials, Workmanship, Site Preparation and Moisture exclusion - Unlikely to be relevant other than adopting normal good working practices.

Part D Toxic Substances - Unlikely to be relevant.

Part E Sound Insulation - Unlikely to be relevant.

Part F Ventilation - Unlikely to be relevant other than common sense design.

Part G Hygiene - Unlikely to be relevant unless you are fitting bathrooms and kitchens.

Part H Drainage and Waste Disposal - May be relevant and important to work to approved methods and practices.

Part J Combustion appliances and fuel storage - Unlikely to be relevant.

Part K Protection from falling, collision and impact - Unlikely to be relevant in single storey buildings without stairways.

Part L Conservation of fuel and power - This section will be very relevant if your intention is to provide a heating system in the building or cabin. It will be necessary to meet the required standards of insulation in the roof, floor walls and glazing.

Part M Access to and use of buildings - This section will be relevant if disabled access is a requirement for the structure.

Part N Glazing - This will be relevant and generally assures that all doors, glazed side panels and windows below 800mm above the floor are provided with break safe glass.

Part P Electrical Safety - Generally always relevant. Usually achievable by having the works performed by a competent and registered electrician who can self certify their work to Part P standard.

regards

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"Take nothing but a picture,
leave nothing but footprints!"
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"Oh! The drama of it all."
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"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
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Edited: 11 June 2012 at 11:15 PM by rocknroll

In reply to Zs.
This is an extension to a friends place who has already lives in a similar size one, so this will give a couple more bedrooms.
This is on a proper insulated concrete bed and plumber is installing his bits.
BUT having installed so many fireproof downlights and being aware of Fire Risks !. I done some checks.
BUT, I also want something like this due to the cost of housing for our kids and we have the space and it will complement my "Solar Tracker" controlled I hope by my "RaspberryPi".
Rgds.

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Helping others today enables
others to help you tomorrow.

Two important words in that document RnR refers to SLEEPING ACCOMMODATION and lets be honest even if it does not have planning permission for sleeping accommodation we need to assume it will be used in that manner.

Gordon hasn't mentioned how if at all it is divided up and whether it has a bath/ shower room.

Andy

Log cabin, i thought we was talking about a shed not someones half ***** house.

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry