Maintenance free joints

[BobPhillips]

In another thread that I read, someone commented on maintenance free joints. Assuming that insulated joints are used with a proper ratchet crimping tool, is it absolutely necessary to also add heatshrink? if it is, should that be a cover that goes over all three wires togerther as well as the casing, or is it acceptable to just have each individual wire covered?

I ask as I am raising some sockets and not all of them are fed down the wall so I need to join the cable. Getting a heatshrink to cover all three wires together seems difficult to obtain. I couldn't get any in our local elcetrician's shop, although they did have individual wire heatshrink, and the guy there suggested wrapping it in amalgam tape. Is this suggestion acceptable, from a safety and regulatory perspective?

TIA.

 

[AndrewDavie]

I order my heatshrink off ebay.
It is slightly more of a pain as you have to stagger the crimps so as to avoid a bunch in the middle that the heatshrink won't pass over.

 

[BobPhillips]

Thanks Andrew, any particular supplier?

Staggering I was aware of, it gets a bit thick otherwise doesn't it

 

[ericmark]

Where I worked we had an RS account so it all came from RS. Each wire had standard heat shrink and the one over the lot was epoxy coated heat shrink.

As to self amalgamation tape it is good but creeps so standard tape then self amalgamation tape then standard tape works well but not self amalgamation tape on it's own.

 

[EFLImpudence]

Assuming that insulated joints are used with a proper ratchet crimping tool, is it absolutely necessary to also add heatshrink?

No. If there is room, you could put the joints in an enclosure with cable clamps.
If not then heatshrink or self-amalgamating tape.

should that be a cover that goes over all three wires together as well as the casing

Yes. you should replace the sheath.

Others will disagree but crimps should not be used on solid core conductors.

 

[EFLImpudence]

As to self amalgamation tape it is good but creeps standard tape then self amalgamation tso ape then standard tape works well but not self amalgamation tape on it's own.

The other way round, surely - creep-wise that is.

 

[ericmark]

As to self amalgamation tape it is good but creeps standard tape then self amalgamation tso ape then standard tape works well but not self amalgamation tape on it's own.

The other way round, surely - creep-wise that is.

If only self amalgamation tape is used over time the wires can contact each other. But if small amount of standard tape used first then the self amalgamation tape may become very thin in parts but due to standard tape there will be no insulation break down.

Buried in a wall one assumes not pressure on the joint so no problem but I would still use both tapes just in case.

 

[JohnW2]

No. If there is room, you could put the joints in an enclosure with cable clamps. If not then heatshrink or self-amalgamating tape.

I agree that putting the 'bare' crimped joints in an enclosure is an alternative to heatshrink/tape. However, you seem to be implying that cable clamps are required if there is no heatshrink/tape, but not if there is. Is that what you intended to imply and, if so, could you possibly explain?

Kind Regards, John

 

[EFLImpudence]

I agree that putting the 'bare' crimped joints in an enclosure is an alternative to heatshrink/tape. However, you seem to be implying that cable clamps are required if there is no heatshrink/tape, but not if there is. Is that what you intended to imply and, if so, could you possibly explain?

In a way, I was.

I was thinking that if the joints are not sealed by whatever means then they would be in the open (not buried) and so would require restraints.


Of course, now you mention it, the rest of the cable could be buried with the joints in a buried box without cable clamps.

However, heatshrink sealing the cable would be better than this for moisture prevention.

 

[BobPhillips]

Gentlemen, I am somewhat confused as to what is required and what is best by the to-ing and fro-ing.

To sum it up, my joints are in my lounge, one on the inside skin of an exterior wall the others on interior walls, and will be within an enclosure which I want to cover with skirting board, therefore not accessible. I will be crimping each individual wire within my cable, but do I
- need to individually heatshrink each wire?
- and/or heatshrink all threes wires and over the cable?
- or use amalgam tape (and standard insulation tape first (and after))?

 

[sparkwright]

Since applying heat shrink is a problem, I would suggest sliding plastic conduit over the joint/cables.

Ideally you should be replacing the entire cable. Or even doing the joint under the floor (if a suspended wooden floor) would be more satisfactory.

 

[JohnW2]

To sum it up, my joints are in my lounge, one on the inside skin of an exterior wall the others on interior walls, and will be within an enclosure which I want to cover with skirting board, therefore not accessible. I will be crimping each individual wire within my cable, but do I
- need to individually heatshrink each wire?
- and/or heatshrink all threes wires and over the cable?
- or use amalgam tape (and standard insulation tape first (and after))?

If, when you say "within an enclosure" you mean within some sort of plastic box, then I don't think you need to do any of those things to your crimped joints. As you have seen, some people might suggest that the enclosures should be ones that include cable clamps/restraints (to avoid any risk that the crimped joints could ever be pulled apart) - but I'm not at all sure than many would worry about that.

Do I take it from what you've said that the entire path of the cable (including that in this 'enclosure') will be vertically aligned with the new position of the sockets - so that the cable remains within the required 'safe zones' throughout its length? Also, if these were new sockets, regulations would require them to be RCD protected, and I think many might interpreting that regulation as still applying if you move existing sockets - so, if the sockets are not already RCD-protected, you may have to address that issue.

Kind Regards, John