Insulated through crimps and heat shrink - settle an argument

[adamh]

as above i've seen a few posts and from what i can make out everybody does this . I dont know the BS number but was led to believe they are a maintenance free compression joint ,
and when heatshrinking as well i would say have good protection from water ingress moisture etc.

A new lad has started at my work who says that this method of jointing cables is unacceptable when buried in walls to be plastered, had a bit of an argument over it and he has asked his tutor for l3 last night who says they can not be burried in walls etc because they are not waterproof only weatherproof as they are hermetically sealed when heat shrunk and if the wall became wet it would become live!!

I just laughed it off and said his tutor sounds like a clown i did use a different word to be honest ha and i also said what ip protection do your normal 25mm metal k/o b/boxes offer as they would be affected by the same situation. at which point he quoted two regs from the BGB i cant remember the no's but i can get them.

The gist of it was all joints need to be accessible for inspection and maintenance with the exception of 1's in MF accessories and there was something else I just said its not an accessory and it will have a bs no im sure stating it is maintenance free which i dont know.

Any help on this 1 as he said his tutor is amazing and i said i will check on a forum i use as there are people on it far more knowledgable than me ...

 

[PC Electrics]

Crimped joints with wrap of self amalgamating tape or normal heatshrink are perfectly acceptable to be buried in plaster. Obviously the joints must be made correctly and the shrink or wrap must overlap the ends of the remaining sheath. Use adhesive lined heatshrink if there is any likelyhood of water around the joint.

This is exactly what these products are made for.

the joints can end up a little bulky if you make all 3 conductors the same length, so I offset the lengths to combat this. makes for a slimmer joint when it's only going into 12mm or so of plaster. Doesn't matter under a floor of course.

 

[Guest55]

Agree with PC , perfectly acceptable means of connection.
And how waterproof do they need to be clipped INSIDE a house , sandwiched between brick and plaster lol ?
Done correctly they are maintainence free and not required to be accessable.

 

[i=p/u]

i bought 1.5mm s.w.a crimps , used my new crimpers and yes they are tight but i can pull them apart, but i reckon ive mastered it after 1 -2 goes

 

[ste mac]

I'm of the same opinion as Biff & PC above perfectly acceptable if done correctly. I have a heatgun, crimps, ratchet crimper and various sizes and colours of heatshirnk in the van and often use these joints buried in plaster. I always use glue lined heatshrink for the outer sheath & I have never had any problems.

Reg 526.3 Every connection shall be accessible for inspection, testing and maintenance, except for the following:

(iv) A joint made by welding, soldering, brazing or appropriate compression tool.

 

[Guitarist]

Reg 526.8 states -

"Cores of sheathed cables from which the sheath has been removed....shall be enclosed as required by regulation 526.5"

Basically I understand this to mean that if you remove the original sheath then it should be enclosed. However, one of the means of enclosing in regulation 526.5 is by the use of non-combustible building materials.

So, if you crimp and sleeve it then it could be argued that the joints (while maintenance free) should be in an enclosure due to the fact that the original (tested) sheath has been removed. On the other hand, if you plaster over said joints, then they have been enclosed.

Imo, both ways are fine

 

[ste mac]

But are you not enclosing the cores by reinstating the removed sheath with heatshrink sleeving?

 

[Guitarist]

But are you not enclosing the cores by reinstating the removed sheath with heatshrink sleeving?

Technically, no. The original sheath will have been tested to various standards. Can you guarantee that your heatshrink is equal-to or better than the original? I think you would be hard-pressed to prove it.

 

[simonk]

This all sounds a bit rough having crimps buried in plaster like that, just like it would be for junction boxes and stuff, worse if anything as you've got no big 'air' gap around the joint to stop direct moisture contact. I would never trust heatshrink alone to stop moisture ingress. Why would you need to do this anyway?

 

[adamh]

It wouldnt be the first thing i would do i admit but it is nice to be able to!

usually for lowering of sockets etc obviously always done in zones.

 

[MarkieSparkie]

BS7671:2008, Amt 1:2011, 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



Note 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. So a crimped termination, whether covered with supplementary insulation (e.g. heat-shrink sleeve [glued or not] or self-amalgamating tape) or not and buried directly in a wall with building material (e.g. plaster) does not comply with BS7671:2008, Amt 1:2011, 526.5 (iii).

Also any type of tape or sleeving, is defined as supplementary insulation NOT an enclosure, even if it completely seals and/or covers the termination. Any cable conductors covered with supplementary insulation to effectively recreate the original double insulation outer sheath of the original cable, will need to be at least equivalent to that of the original cable product standard to comply with BS7671:2008, Amt 1:2011, 133.1. The cable product standards do not specify an insulation withstand capability, as jointing is prohibited. However, BS7671:2008, Amt 1:2011, 412.2.4.1, Note 1, states … the insulation cable system must be at least equivalent to requirements set out in BS EN 61140 for reinforced insulation and this would require impulse dielectric strength testing as detailed in the standard to verify that any applied insulation was indeed equivalent to the original cable insulation.

 

[Deleted member 9648]

^^^^great to have my long held belief that crimps buried in a wall are unacceptable confirmed. Insulated crimps on solid core cables are particularly unreliable. You dont need reg numbers to know burying a joint in a wall is a bodge.

 

[Rockingit]

BS7671:2008, Amt 1:2011, 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



Note 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. So a crimped termination, whether covered with supplementary insulation (e.g. heat-shrink sleeve [glued or not] or self-amalgamating tape) or not and buried directly in a wall with building material (e.g. plaster) does not comply with BS7671:2008, Amt 1:2011, 526.5 (iii).

Also any type of tape or sleeving, is defined as supplementary insulation NOT an enclosure, even if it completely seals and/or covers the termination. Any cable conductors covered with supplementary insulation to effectively recreate the original double insulation outer sheath of the original cable, will need to be at least equivalent to that of the original cable product standard to comply with BS7671:2008, Amt 1:2011, 133.1. The cable product standards do not specify an insulation withstand capability, as jointing is prohibited. However, BS7671:2008, Amt 1:2011, 412.2.4.1, Note 1, states … the insulation cable system must be at least equivalent to requirements set out in BS EN 61140 for reinforced insulation and this would require impulse dielectric strength testing as detailed in the standard to verify that any applied insulation was indeed equivalent to the original cable insulation.

TBH, I think the wording of the reg is less watertight than a crimp & shrink joint. The main let-out is the use of the word COMBINATION, so a mix and match of methods which individually do the job is perfectly fine. A mechanical compression crimp, some suitable grade heat shrink, and a decent dollop of plaster.....that's a combination if ever I heard one!

 

[Guitarist]

I think that common sense would dictate that if you sleeve a joint then cover it in wet plaster, unless you can guarantee a completely watertight seal all around, there is going to be some water seepage into the joint. This may be fine for a while, but how does anyone know whether corrosion is occurring behind the plaster and how long before it all goes wrong?

 

[Rockingit]

^^^ put a few amps through it and the plaster will dry all the quicker......