Crimping and plastering over?

[DNS1]

Asked about this a while back, but read a few things since that have made me wonder if I was doing the right thing...

Got to join 2 pieces of T+E in the middle of a wall for a light switch. The rest of the cabling is plastered over. I'm intending to plaster over the joint too when it's made (currently it's a joint box hanging out a hole in the wall)

I don't want to have to leave it accessible (don't want a box/blanking plate halfway up the wall) so planned to crimp and sleeve, then plaster in.

Was told a while back that this method was compliant, but now I'm not so sure (read a few posts on another forum).

Any tips would be much appreciated. I'm not a pro sparks (obviously!) but intend to be one in few years so want to make sure I get these things right from the beginning.

 

[MarkieSparkie]

The plastered in, crimped joints in heat shrink sleeve, argument has been a failed defence in at least two court cases resulting from electrical accidents.
All you guys that are heat shrink sleeving crimped joints and then plastering over, seem to have forgotten about:
526.5 Every termination and joint in a live conductor or PEN conductor shall be made within one of the following or a combination thereof:
i) A suitable accessory complying with the appropriate product standard.
ii) An equipment enclosure complying with the appropriate product standard.
iii) An enclosure partially formed or completed with building material which is non-combustible when tested to BS476-4
Specifically 526.5 (iii) an enclosure can be PARTIALLY formed or COMPLETED with non-combustible building material tested to BS 476-4. The enclosure CANNOT therefore be made totally from building material.
The most common infringement of this is a crimped termination, covered with supplementary insulation (e.g. heat-shrink sleeve) and buried directly in the wall with building material (e.g. plaster).
Any type of tape or sleeving used in addition to basic insulation, is defined as supplementary insulation, even if it completely encloses the termination it is NOT an enclosure.
Any cable conductors covered with supplementary insulation, to effectively recreate the double insulation of the original cable, needs to be at least equivalent to that of the original cable product standard and would require impulse dielectric strength testing to confirm this. The cable product standards do not specify an impulse withstand capability. However, 412.2.4.1, Note 1, tells us that cable insulation must be at least equivalent to requirements of BS EN 61140 for reinforced insulation, which does specify impulse withstand capability.

 

[Rockingit]

Specifically 526.5 (iii) an enclosure can be PARTIALLY formed or COMPLETED with non-combustible building material tested to BS 476-4, the enclosure CANNOT therefore be made totally from building material. The most common infringement of this is a crimped termination, covered with supplementary insulation (e.g. heat-shrink sleeve) and buried directly in the wall with building material (e.g. plaster).
Any type of tape or sleeving, is defined as supplementary insulation, even if it completely encloses the termination it is NOT an enclosure.
Any cable conductors covered with supplementary insulation, to effectively recreate the double insulation of the original cable, needs to be at least equivalent to that of the original cable product standard and would require impulse dielectric strength testing to confirm this. The cable product standards do not specify an impulse withstand capability. However, 412.2.4.1, Note 1, tells us the cable insulation must be at least equivalent to requirements of BS EN 61140 for reinforced insulation.

Where are you quoting this from?

 

[Darkwood]

Lets just establish what is needed hear, as i went to college 20yrs ago for 4 yrs instead of the fast track 2 yr courses that i see nowadays, you actually got indepth discussions on everything as well as the basics required. Well to establish just crimping the cable wont suffice; the cable is double insulated for a reason the inner insulation gives the required dielectric strength under the normal working conditions of the cable, the outer sheath is on to protect the inner insulation from environmental effects that the cable would need to put up with under normal operation including damp and chemicals associated with plaster and walls etc.. even if capped over there is a possibility of damp in the wall effecting the joint.
What you need to acheive here is the same standard of insulation and environmental protection as a good piece of cable would acheive. One way of which ive utilised in the past is heat shrink crimps for the joint with a shrinkable sleeve to extend fully across the joint with a overlap onto the good section of cable. This then gives a joint that can be plastered over, also to mention its wise to get sleeving which has a glue/paste that seals the joint from moisture inpregnation.

If this is a one off its an expensive route to go as you may need to buy a heat gun etc, but an amalgamating tape (as mentioned above) may suffice if you read the spec up on the tape to see if it meets requirements for the situe but is arkward to put on as it required to be wrapped on taut and as you dont have access to swing it behind the cable it could be a poor seal.
Poor joints may give questionable IR readings at some point thus leading to a possible repair or replacement of the offending cable and not worth the risk to attempt a joint your not entirely sure of.

 

[GLENNSPARK]

Lets just establish what is needed hear, as i went to college 20yrs ago for 4 yrs instead of the fast track 2 yr courses that i see nowadays, you actually got indepth discussions on everything as well as the basics required. Well to establish just crimping the cable wont suffice; the cable is double insulated for a reason the inner insulation gives the required dielectric strength under the normal working conditions of the cable, the outer sheath is on to protect the inner insulation from environmental effects that the cable would need to put up with under normal operation including damp and chemicals associated with plaster and walls etc.. even if capped over there is a possibility of damp in the wall effecting the joint.
What you need to acheive here is the same standard of insulation and environmental protection as a good piece of cable would acheive. One way of which ive utilised in the past is heat shrink crimps for the joint with a shrinkable sleeve to extend fully across the joint with a overlap onto the good section of cable. This then gives a joint that can be plastered over, also to mention its wise to get sleeving which has a glue/paste that seals the joint from moisture inpregnation.

If this is a one off its an expensive route to go as you may need to buy a heat gun etc, but an amalgamating tape (as mentioned above) may suffice if you read the spec up on the tape to see if it meets requirements for the situe but is arkward to put on as it required to be wrapped on taut and as you dont have access to swing it behind the cable it could be a poor seal.
Poor joints may give questionable IR readings at some point thus leading to a possible repair or replacement of the offending cable and not worth the risk to attempt a joint your not entirely sure of.

well i understand what you are saying here....but also for one length of cable......just pull a new in far gawds sake..lol....:icon6:

 

[Darkwood]

well i understand what you are saying here....but also for one length of cable......just pull a new in far gawds sake..lol....:icon6:

LOL yes agree but occassionally not an option ..... her new tiled bathroom floor above with underfloor heating, the cable drop down the back of a joist close to wall so no real useful access underneath either, but in my yrs only ever used this method twice because of limitations to access the cable.

 

[Darkwood]

Specifically 526.5 (iii) an enclosure can be PARTIALLY formed or COMPLETED with non-combustible building material tested to BS 476-4, the enclosure CANNOT therefore be made totally from building material. The most common infringement of this is a crimped termination, covered with supplementary insulation (e.g. heat-shrink sleeve) and buried directly in the wall with building material (e.g. plaster).
Any type of tape or sleeving, is defined as supplementary insulation, even if it completely encloses the termination it is NOT an enclosure.
Any cable conductors covered with supplementary insulation, to effectively recreate the double insulation of the original cable, needs to be at least equivalent to that of the original cable product standard and would require impulse dielectric strength testing to confirm this. The cable product standards do not specify an impulse withstand capability. However, 412.2.4.1, Note 1, tells us the cable insulation must be at least equivalent to requirements of BS EN 61140 for reinforced insulation.

I also struggle to find this anywhere i assume its an interpetation from yourself of the reg', regardless of this their are shrinkcrimps and heatshrink sleeving aplenty out there that meets and goes well beyond the requirements of the joint for dielectric strength and environmental protection, just review any spec' sheet related to the heat shrink and you'll find it give a higher degree of protection than the original insulation does, but you do end up paying over the odds for very short bits of sleeving.

 

[GLENNSPARK]

LOL yes agree but occassionally not an option ..... her new tiled bathroom floor above with underfloor heating, the cable drop down the back of a joist close to wall so no real useful access underneath either, but in my yrs only ever used this method twice because of limitations to access the cable.

No probs dark.....you see this kind of thread can quickly become a yes n no camp....with slanging....like a chimps party..lolffs....:tounge_smile:

 

[SoulTy1066]

a box and blank plate tells where the cable drop is. If it's jointed and plastered then how would anyone know that there is a cable there?

 

[trev]

a box and blank plate tells where the cable drop is. If it's jointed and plastered then how would anyone know that there is a cable there?

Because the cable will be in a safe zone designated by the position of the switch..hopefully

 

[SoulTy1066]

i may be being thick but if the switch is removed then it wouldn't be in a safe zone ? you wouldn't know the cable was there

 

[Des 56]

You may be an ex contributor to this forum unless you edit that post

 

[trev]

The op hasn't mentioned removing the switch mate. I understand what you're saying though. the thing is any accessory can be removed at a later date and we can't install with future idiots in mind can we?
By the way themods are having a clampdown on even implied bad language, twould be bad crack for you to get a telling off

 

[Marvo]

i may be being a **** **** but if the switch is removed then it wouldn't be in a safe zone ? you wouldn't know the cable was there

Using Spoonerisms isn't a way to sidestep the 'zero tolerance for bad language' policy of the forum. Please be warned.

 

[DNS1]

Oh crap, hadn't expected this to turn into a 3 page thread!

Here's the story...

Doorway moved from one corner of the room to another (10 feet down same wall). Switch needed to be moved horizontally across the wall. The cable to the original switch came from directly above it.

To keep the original cable in a safe zone, I installed a double socket directly below the location of the old switch. I ran the new cable horizontally to the new switch (chased and plastered).

Yes, it would have been good to have been able to replace the whole cable run, but simply not an option in this case. No access from above without removing a laminate floor.

 

[Rockingit]

Yes, it would have been good to have been able to replace the whole cable run, but simply not an option in this case. No access from above without removing a laminate floor.

Which very neatly upholds my comment that when needs must, they must.