Armour termination

[Adam_151]

I have to say that just sleeving the armour and terminating it into an earth terminal does seem a neat way of doing it. Though, I do find myself thinking that on most cables I've dealt with, it would be a fairly thick bit of wire by the time you got all the strands together !

No. It looks a complete mess. They don't really bunch into a neat bunch, just rather a big untidy one that splits off into different directions near the cable it emerges from. Its a favorite of aircon installers though!

Its nothing like doing the same thing with SY, which can be quite tidy (although technically not quite right) and you are putting the SY screen to earth just for EMC reasons, its not the CPC.

 

[JohnW2]

I have to say that just sleeving the armour and terminating it into an earth terminal does seem a neat way of doing it. Though, I do find myself thinking that on most cables I've dealt with, it would be a fairly thick bit of wire by the time you got all the strands together !

When the technique is used, IMO people do not generally attempt to get all the strands of the armour into a single bunch - which, as you say, would probably be too thick to handle/route. Instead, they usually split the strands into several bunches, separately sleeved and separately terminated in an earth bar. It may not look as neat as gland termination, but I still don't understand why so many people seem to regard it as an 'unthinkable' method.

Kind Regards, John.

 

[JohnW2]

The other point that I was taught was the gland was only for the electrical connection and not to provide mechanical strain relief.

Indeed so. Particularly with a non-waterproof gland, the only mechanical support is that provided by the electrical termination of the armour - and, as we know, that is regarded as a definite no-no for any type of cable, since there is then no strain relief at all protecting the electrical termination.

Kind Regards, John

 

[holmslaw]

..

 

[LUG]

I have to say that just sleeving the armour and terminating it into an earth terminal does seem a neat way of doing it. Though, I do find myself thinking that on most cables I've dealt with, it would be a fairly thick bit of wire by the time you got all the strands together !

the only way to do it is to put about 3-4 strands into each piece of sleeving otherwise its far too stiff and unmanageable.

 

[ban-all-sheds]

The other point that I was taught was the gland was only for the electrical connection and not to provide mechanical strain relief.

It may not (nor should it) provide "strain relief", but it mechanically ties the cable to the surface it's passing through.

I'm not one of those fools who thinks that no matter what nonsensical rubbish a manufacturer puts in his instructions they must be given precedence over the rest of the regulations, and must be followed no matter how many non-compliances result.

There are several hundred pages of regulations in BS 7671, arrived at via several hundreds of man-years of work. You don't throw them away in favour of one or two pages of instructions from a manufacturer.

Even if there are MI's saying that you can dispense with a gland and twist armour strands together and put them in an earth bar, I am in no doubt whatsoever that doing so would be an unarguable contravention of the requirement for good workmanship.

 

[LUG]

The other point that I was taught was the gland was only for the electrical connection and not to provide mechanical strain relief.

It may not (nor should it) provide "strain relief", but it mechanically ties the cable to the surface it's passing through.

I'm not one of those fools who thinks that no matter what nonsensical rubbish a manufacturer puts in his instructions they must be given precedence over the rest of the regulations, and must be followed no matter how many non-compliances result.

There are several hundred pages of regulations in BS 7671, arrived at via several hundreds of man-years of work. You don't throw them away in favour of one or two pages of instructions from a manufacturer.

Yes
Yes
Yes

Even if there are MI's saying that you can dispense with a gland and twist armour strands together and put them in an earth bar, I am in no doubt whatsoever that doing so would be an unarguable contravention of the requirement for good workmanship.

Surely an armoured cable is just another cable.

If a twin & earth doesn't need a brass gland then should steel wired armour need one? That is on the assumption the strength of the armour is required elsewhere and not at the point of entry into an enclosure.
The lack of good workmanship you argue is is fact techniques learnt during my apprenticeship so I rather take offence at the suggestion.
I will offer that the technique may in fact improve on the quality of the connection between armour and earth as there is only one point for failure (consisting of 1/2 dozen parallel terminations) as opposed to a minimum of 5 in series using a brass gland.
As a matter of interest how would people here assemble a resin filled jointing kit for an armoured cable? I must confess its been a while since I have done one but assume screw terminals are no longer permitted as once filled they become inaccessible.

 

[JohnW2]

As a matter of interest how would people here assemble a resin filled jointing kit for an armoured cable? I must confess its been a while since I have done one but assume screw terminals are no longer permitted as once filled they become inaccessible.

One might think so, but this is seemingly another of those anomalies of the regs - 526.3(ii) indicates that a "compound-filled or encapsulated joint" does not have to be accessible, without any qualification about the nature (screw terminals or otherwise) of the joint between conductors!

Kind Regards, John.

 

[LUG]

As a matter of interest how would people here assemble a resin filled jointing kit for an armoured cable? I must confess its been a while since I have done one but assume screw terminals are no longer permitted as once filled they become inaccessible.

One might think so, but this is seemingly another of those anomalies of the regs - 526.3(ii) indicates that a "compound-filled or encapsulated joint" does not have to be accessible, without any qualification about the nature (screw terminals or otherwise) of the joint between conductors!

Kind Regards, John.

Indeed many resin joints are directly buried in the ground.
I raised the point because all the kits I have used, in the distant past, have never included a "gland" for the armour.

 

[JohnW2]

Indeed many resin joints are directly buried in the ground. I raised the point because all the kits I have used, in the distant past, have never included a "gland" for the armour.

Indeed. I think what we are dealing with here are deeply entrenched traditions and teachings. As you, I and others have pointed out, in engineering terms the 'unthinkable' (in some people's minds) method of terminating SWA is (assuming adequate strain relief is provided) at least as satisfactory (and safe) as is the use of an SWA gland, so the only real basis for any argument is that of aesthetics - and even that is not really materially different from what one would have with split con.

Kind Regards, John.

 

[RF Lighting]

As a matter of interest how would people here assemble a resin filled jointing kit for an armoured cable? I must confess its been a while since I have done one but assume screw terminals are no longer permitted as once filled they become inaccessible.

One might think so, but this is seemingly another of those anomalies of the regs - 526.3(ii) indicates that a "compound-filled or encapsulated joint" does not have to be accessible, without any qualification about the nature (screw terminals or otherwise) of the joint between conductors!

Kind Regards, John.

It's not an anomalie, It's people who actually understand what they are talking about making perfectly sensible exemptions to a regulation.

All the cast joints I've ever used have four screws to joint each conductor, and how exactly do you think a screw is going to work loose when it's cast in rock hard resin?

 

[JohnW2]

It's not an anomalie, It's people who actually understand what they are talking about making perfectly sensible exemptions to a regulation. All the cast joints I've ever used have four screws to joint each conductor, and how exactly do you think a screw is going to work loose when it's cast in rock hard resin?

I guess that's a matter of opinion. I've never seen any suggestion that having four screws for each connection would make it any more acceptable for a (non-encapsulated) screw-terminal joint to be inaccessible - and, as for your second point, isn't one of the problems (maybe the main problem) with screwed joints believed to be creep in the material of the conductor (resulting in secondary loosening of the screw), rather than primary mechanical 'working loose' of the screws (which would probably be fairly unlikely to arise in the absence of creep, unless one's house was next to the M25 or above a shallow underground train tunnel!)?

Kind Regards, John.

 

[17thman]

As a matter of interest how would people here assemble a resin filled jointing kit for an armoured cable? I must confess its been a while since I have done one but assume screw terminals are no longer permitted as once filled they become inaccessible.

One might think so, but this is seemingly another of those anomalies of the regs - 526.3(ii) indicates that a "compound-filled or encapsulated joint" does not have to be accessible, without any qualification about the nature (screw terminals or otherwise) of the joint between conductors!

Kind Regards, John.

It's not an anomalie, It's people who actually understand what they are talking about making perfectly sensible exemptions to a regulation.

All the cast joints I've ever used have four screws to joint each conductor, and how exactly do you think a screw is going to work loose when it's cast in rock hard resin?

Well said RF

The idiot that is JohnW2, has probably never made a swa resin filled joint in his life.
He does not realise that that it can never work loose.

To JohnW2. would you like me to come to your house and terminate some swa with the strands seperated into rough sections and sleeved into a terminal?. probably compromising the IP rating of the entry, without a gland.

I am sick of your postulations and your attempts to get someone to agree with you.

Your eristic attitude and complete misunderstanding of the difference between eathing and bonding has become boring.

your specious comments drew me in for about a week, but you tireless attempts to extort some sort of favour out of contributors to your own ends and to try and find cohorts to your constant moaning about BS 7671 annoys me.

Some times I laugh, sometimes I cry when i read your nonsence.

Do you think that because you constantly quote regulations and then try to dissect it and infer it into redciculous situations, I amnot interested.

Neither would any OP.

For the first time i have hijacked a post. Sorry, but i wanted to say it

 

[ban-all-sheds]

I raised the point because all the kits I have used, in the distant past, have never included a "gland" for the armour.

Yes, but they have, and are designed to have, an alternative means of providing continuity for the armour.

The item designed to be the appropriate way to terminate SWA into an enclosure like a CU, as opposed to a resin-filled joint, is a gland.

 

[SimonH2]

To JohnW2. would you like me to come to your house and terminate some swa with the strands seperated into rough sections and sleeved into a terminal?. probably compromising the IP rating of the entry, without a gland.

If you are going to pick a point to fight on, pick a valid one

From observation, the vast majority of terminations indoors don't have a specific IP rating requirement and the cable is terminating into an enclosure which itself has no IP rating. In fact, unless you choose a (more expensive and bulkier) sealed gland, then there is no protection against water ingress.

Someone earlier asked if it was considered necessary to always take a (for example) T&E cable into an enclosure with a gland ? I think the answer is "rather infrequently" - most T&E entering an enclosure via some trunking (in an industrial environment), or through a hole with (unless it's coming through a big hole in the back of the board) a grommet.

My main concerns would be the bulk and stiffness of the armour, and the number of ways in the earth bar it would take up. In a plastic enclosure, the use of a gland may well distort the enclosure (I'm thinking CUs here which tend to have large and flexible sides) as the cable is likely to be stronger than the enclosure !
In terms of appearance, if routed well then an SWA taken through a grommet and terminated as described may well look neater than one terminated in a relatively bulky gland - that's a matter of preference, and SWA is rarely chosen for it's aesthetics.