MF and Crimps

[Pete999]

Just a quick question, I should be aware of the answer, but I'm not sure. Are inline crimps classed as Maintenance free joints?

 

[Taylortwocities]

Yes, its one of the approved solutions for a cable joint in the regs. Its been in there a long time, along with welded and soldered joints. They were in the regs a LONG time before the issue of MF joints surfaced.
I've only got my green book to hand.
reg 526.3 (iv) = appropriate compression tool = crimps.

 

[Pete999]

Yes, its one of the approved solutions for a cable joint in the regs. Its been in there a long time, along with welded and soldered joints. They were in the regs a LONG time before the issue of MF joints surfaced.
I've only got my green book to hand.
reg 526.3 (iv) = appropriate compression tool = crimps.

Right, OK thanks, now an interesting thought occurred to me, could be talking out of my backside, but interesting none the less, what do people think of my concerns?

To be classified as MF the box/connectors have to marked MF am I right so far? so as an example Wagos can't be classed as MF unless they are in a box marked MF, is that correct?

So a joint has to be accessible unless it is made up of MF components? my concerns are the crimp, as you say according to BS7671 are MF,

There have been posts recently regarding people drilling through cables in a wall and the repairs to the cable are crimped and plastered over, not accessible, so how can this method be considered OK as it is neither accessible, or MF, as the joint is not in a MF marked enclosure, am I over thinking, talking rubbish or whatever?

 

[Taylortwocities]

Over-thinking. 526.3 give six SEPARATE options for connections that are not accessible for inspection etc.
one of the options (iv) is welding, soldering, brazing or joining with a compression tool. The joint (from another reg) needs to be sleeved, but doesnt need to be in any other sort of enclosure.

a separate option (vi) details what you are supposed to do if the connection is made along the BS5733/MF route.

 

[Des 56]

With any joint,be it soldered or crimped,the insulation and/or cable protection has to be re instated

Heat shrink over the crimps and conductors will give protection for ingress of moisture etc,conduit will provide a degree of mechanical/impact protection

 

[Pete999]

Have to say crimping and burying in the wall, with or without heatshrink, no I wont say for deference to my forum colleagues.

 

[Dave OCD]

I'll say that would be a proper bodge.

 

[Marvo]

I might be wrong, I don't have a copy of the latest UK regs but doesn't an MF joint require strain relief?

 

[sparksburnout]

I'll say that would be a proper bodge.

So how would you do it then, in your typical domestic husbands drilled through the cable scenario?

 

[sparksburnout]

I might be wrong, I don't have a copy of the latest UK regs but doesn't an MF joint require strain relief?

If its buried in a wall why does it need strain relief?

 

[Dave OCD]

So how would you do it then, in your typical domestic husbands drilled through the cable scenario?

It would depend on the wall material, if I could gain a little slack on the cable or not etc but regardless I'd make every effort to put the repair or joint in an enclosure.

 

[Marvo]

If its buried in a wall why does it need strain relief?

I don't know if it does, I don't work to UK standards, but for the same reason if a joint is under floorboards or above ceiling in a roofspace why would it require strain relief there? No idea what those those reasons actually are but I remember with the Line Products MF connection there were special cable straps to fulfil the requirement of strain relief on an MF joint.

 

[sparksburnout]

It would depend on the wall material, if I could gain a little slack on the cable or not etc but regardless I'd make every effort to put the repair or joint in an enclosure.

We were talking about a cable embedded in a wall that has been drilled through, were we not??

 

[Dave OCD]

Yes of course, why ?

 

[sparksburnout]

Yes of course, why ?

Well, if the cable was embedded in a masonry/plastered wall just wondering how an enclosure would help or be practical? How are you going to gain any slack in such circumstances??

 

[DPG]

Strain relief is required when joining cables in lofts, under floors etc. because someone can knock/move the cables and cause them to become loose. However this strain relief can be provided by clipping the cables to joists, and fixing the JB to the joist. If the JB is floating, ie. above chucked above a ceiling, in a void, etc. then it must have strain relief provided. Daz

 

[Dave OCD]

Well, if the cable was embedded in a masonry/plastered wall just wondering how an enclosure would help or be practical? How are you going to gain any slack in such circumstances??

I just think it's better to be enclosed if at all possible,no chance of the repair getting soaked when filled in for one thing, generally I'd use a very small IP rated enclosure obviously only if some slack can be gained though. If the cable in question was in oval conduit or even flat capping you can generally get a little spare cable from above.

 

[sparksburnout]

I just think it's better to be enclosed if at all possible,no chance of the repair getting soaked when filled in for one thing, generally I'd use a very small IP rated enclosure obviously only if some slack can be gained though. If the cable in question was in oval conduit or even flat capping you can generally get a little spare cable from above.

Yes good point. I once managed to pull an entire new length in when the cable in question was in capping. Modern 2.5mm seems to be a bit slimmer than that of a few years ago.