Was this acceptable practice in a loft space back in 1995?

[bobdabuilda]

Just been up in the loft of our 14 yr old bryant 'executive' build house to change a cold water tank valve. whilst up there I moved some rockwool and found the loft light shorting out intermittently.

On closer inspection theres a leash of six cables bound together with yellow tape which are chock blocked into the back of the bathroom light below and one of the N wires was loose!

One wire is a 1.5mm three core and earth with the yellow cut back going to the extractor fan, another goes to the shower downlight, isolator switch, pull cord switch and the other two are feed and supply. Surely these should have been wired into a junction box in the loft rather than chock blocked within the bathroom light fitting?

Several of the terminal block ends are stuffed with 4 cables whereas I thought there was an unwritten rule that two was the max? No doubt this is why one of the wires worked loose. Phew am I glad that I discovered it!

Also the cables run OVER the joists and under the insulation! I thought that you had to pass the cabling through the joists as a minimum? I have checked under the rest of the rockwool throughout the loft and all the cabling is just draped over the joists! (thank F they didn't notch the joists as they are like matchsticks!)

Given that this was done in 1995 was it acceptable at that time or just a dangerous and bodged wire job by the contractors? Would I have any recourse with the original builders to pay for a proper sparky to come and redo the job?

 

[Taylortwocities]

The joint is a botched add on and needs sorting..

The cabling should have been clipped to the joists but was probably just thrown over the joists - not best practise but its done everywhere.

The insulation over the top was probably done long after the electrician had finished.

You should never notch or drill roof joists. They are carefully sized to support the roof and you'll weaken them if you make them like swiss cheese.

You'll get no change out of the housebuilder. The NHBC will have run out a long time ago (you'd have trouble getting it sorted even if it was still in force)!

If you are really concerned you'd need to rewire the loft wiring to meet your requirements.

 

[bobdabuilda]

Thanks- but its not an add on as I have the original plans and its all standard fit at the initial build.

Re joist drilling - Calcs for the right joist allow for some holes for services. If the joists are correct size wise, you will be ok drilling holes of 18mm as required in the centre (of the joist cross section) The further into the middle of the room you drill, the weaker the joist will be as the middle is more loaded than the edges, so drill near the joist ends. I think there are guidelines like no nearer than 50mm to top or bottom edge and no less than 150mm from joist ends that I have read somewhere? Any ideas BAS?

Therefore- always drill joists exactly in the middle as this is the neutral axis of the joist where the minimum amount of stress exists
The top surface of the loaded joists are in compression with the bottoms in tension and are therefore the worst place to cut notches or drill holes.




edit -just found this-
Electrical installers often need to drill holes and cut notches in the joists of
supported floors and roof joists, for the passage of cables.
Regulation 522-12-03 of BS 7671 requires that wiring systems must not penetrate an elemen of building construction which is intended to be load bearing unless the integrity of the loadbearing element can be assured after such penetration.

Furthermore, to meet the requirements of Part A - Structure in Schedule 1 of the Building Regulations for England and Wales, it is important that a building structure is not weakened when notches or holes are made in joists; these should never be made larger than necessary.

For single family houses of not more than 3 storeys, guidance on the structural requirements of Part A of the Building Regulations for notches and holes in simply supported* floor and roof joists is explained in paragraph 1 B6 of Approved Document A (1992 edition with 1994 and
2000 amendments). That guidance follows together with illustrated examples.

http://www.voltimum.co.uk/news/3914...-made-in-Supported-Floor-and-Roof-Joists.html

 

[Adam_151]

It sounds like you are reading the rules for floorboard joists... you should never drill pre-formed roof trusses, because as you say, they are lke matchsticks!

 

[bobdabuilda]

One wire is a 1.5mm three core and earth with the yellow cut back going to the extractor fan, another goes to the shower downlight, isolator switch, pull cord switch and the other two are feed and supply. Surely these should have been wired into a junction box in the loft rather than chock blocked within the bathroom light fitting?
Several of the terminal block ends are stuffed with 4 cables whereas I thought there was an unwritten rule that two was the max? No doubt this is why one of the wires worked loose.

Would I be allowed under the part P regs to sort this mess out as its an existing installation or does it have to be a sparky? Was thinking of just making a better job of the chockblock connections and using the dragons den chocbox enclosures all located in the loft instead of the bathroom light! Will also stick rcd pods on the upstairs lighting mcbs to be extra safe.

 

[Taylortwocities]

The further into the middle of the room you drill, the weaker the joist will be as the middle is more loaded than the edges, so drill near the joist ends.

Not quite. regulations state holes should be in cetre line between 0.25 and 0.40 x span - so "near the ends" is not allowed.
Max diameter of hole is 0.25 of joist depth.

It is shown in that diagram in the voltimum link above but you cant read it.
On Site Guide page 59 tells all.

 

[RF Lighting]

I found almost exactly the same in my brothers house. It was built about 3 years ago

 

[Taylortwocities]

Rob, doesn't your sig become unlucky on 12th night?

 

[RF Lighting]

Thought that was tomorrow?

 

[Taylortwocities]

Just giving advance warning - I don't want you to run into problems....

 

[RF Lighting]

 

[bobdabuilda]

The further into the middle of the room you drill, the weaker the joist will be as the middle is more loaded than the edges, so drill near the joist ends. I think there are guidelines like no nearer than 50mm to top or bottom edge and no less than 150mm from joist ends that I have read somewhere? Any ideas BAS?

You only part quoted me!! Apologies as this wasn't intended as definitive advice hence why I put up the NICEIC link after!

Not quite. regulations state holes should be in cetre line between 0.25 and 0.40 x span - so "near the ends" is not allowed.
Max diameter of hole is 0.25 of joist depth.

It is shown in that diagram in the voltimum link above but you cant read it.
On Site Guide page 59 tells all.

Thanks Taylor- you can read it if you click on the downloadable pdf link-

http://www.voltimum.co.uk/popup.php...20floor%20and%20roof%20joists%20PDF%20(336Kb)



Holes
Holes should be within the following limits:
• no greater diameter than 0.25 times the depth of
the joist
• drilled at the neutral axis (where the joist is under
least tension, normally at the centre line of the
joist depth)
• not be less than 3 diameters (centre to centre)
apart
• located between 0.25 and 0.4 times the span
from the support

 

[skenk]

Yes but that refers to joist supporting floors. As has been mentioned (twice in this thread already i think?) ROOF JOISTS SHOULD NOT BE DRILLED

 

[Steve]

Yes but that refers to joist supporting floors. As has been mentioned (twice in this thread already i think?) ROOF JOISTS SHOULD NOT BE DRILLED

UNLESS THEY AREN'T PART OF A PRE-FORMED ROOF TRUSS!

 

[RF Lighting]

Even so, I'd still advise against it.

Ceiling joists in Victorian terraced houses tend to be too small to drill. It's not a new thing.