People's opinion....

[Mr s]

Afternoon to all.....


i have a question to ask all of you and wondered if any of you could help..

I was carrying out some work on one of the other sparks jobs today and questioned why he had three earths at a socket. It is a ring main. Now before you say it it is not a fly lead as it's in plastic dado trunking. Now his reply was that we have been told from now on when using swa to dado trunking to take a tembi clip from the wire sheaf to the socket outlet. I have never heard of this before but I am curious as to what you think. My thoughts where that the sheaf will be earthed via the trunking at the board end with a bolted down banjo and we are using three core so has a core for its cpc.

any feed back would be appreciated..........

 

[Flanders]

It may be if the sockets are for computers and they want to increase the CSA of the earthing put if its only to one socket then I can't see any reason for it, as you have said the swa is terminated at the board end so no reason to do it, By the way whats a Tembi clip,

 

[7029 dave]

No idea WHY.

 

[E.E.I]

Is it on this job only? Could be to reduce the zs values??

 

[Pete999]

Why would you use SWA in plastic Dado trunking? a tenby clip on the SHEATH ?????

 

[E.E.I]

I think the sea is the supply to the dado trunking

 

[E.E.I]

*swa

auto correct!!

 

[Pete999]

Afternoon to all.....


i have a question to ask all of you and wondered if any of you could help..

I was carrying out some work on one of the other sparks jobs today and questioned why he had three earths at a socket. It is a ring main. Now before you say it it is not a fly lead as it's in plastic dado trunking. Now his reply was that we have been told from now on when using swa to dado trunking to take a tembi clip from the wire sheaf to the socket outlet. I have never heard of this before but I am curious as to what you think. My thoughts where that the sheaf will be earthed via the trunking at the board end with a bolted down banjo and we are using three core so has a core for its cpc.

any feed back would be appreciated..........

What size is the SWA? how long is the run? people opinions differ on this subject but IMO it's not ideal to run one cable to feed a Ring FC assuming that's what he has done, as I said that's my opinion

 

[Mr s]

It's about ten meters from the board. Tenby clamps perhaps I should say, what you use to earth copper pipe work etc.... He has run two cables fro the ring main, as I said a three core so be a bit difficult to complete a ring. It's a print copy area so will have printers etc etc. zs readings where 0.11 so not a high zs. And yeah he has said on every job. This guy thinks he is the nuts, he is the firms nic man so what ever he said's the director wants but when I see this I could not see any point to it and would rather not squeeze three earths in one terminal if there is no reason to do so.... It's commercial in London and we use swa in most power situations now days....... It's on an rcbo so so just can't see a reason for this....

 

[Welchyboy1]

Not a good idea to clamp earth straps to swa sheaths

if its suitiably earthed the other end its not really required, however.......

still a bit of a rough way to do things, why not terminate the swa into a suitiable box then feed the dado from there


im sure if his nic area engineer saw his install methods he would put him straight

 

[Flanders]

You should not use one of these clips as it can damage the inner cores of the cable by putting to much pressure on them if your going to terminate the swa it needs to be done with the correct gland

 

[Darkwood]

As above whatever the reason about the earthing link its clear that the use of a tenby clip is poor workmanship and I would challenge the competence of anyone seen doing this, why hasn't a correct gland and banjo earth ring been used or other recognised earth method?

 

[Flanders]

You can get lock rings with a terminal on them so you make off the swa into plastic
see link may be a better idea if required
https://www.google.co.uk/search?q=l...irect.co.uk%2FProducts%2FPRPEN20.html;580;600

 

[Pete999]

You can get lock rings with a terminal on them so you make off the swa into plastic
see link may be a better idea if required
https://www.google.co.uk/search?q=l...irect.co.uk%2FProducts%2FPRPEN20.html;580;600

Are you sure about that statement??

 

[Flanders]

Yes see pictures on link to see how its done

 

[Pete999]

Yes see pictures on link to see how its done

What link

 

[Mr s]

Thank you very much for your feed back and from what you have said it is as daft as I thought. Thing is I didn't want to challenge him because he is the man who knows it all APPARANTLY.

thanks again people

 

[Geordie Spark]

Yes see pictures on link to see how its done

As a Time Served Precision Engineer I have to say that thing is total cack!!!

 

[Pete999]

As a Time Served Precision Engineer I have to say that thing is total cack!!!

Same as him

 

[Cyril Molony]

If it a PVC SWA to BS5467 and you are use one of the core/conductor as a circuit protective conductor then armouring must only be terminated at the supply, (to provide protection against mechanical damage or piercing of the amoured) at the load end it must be terminated into a not conductive box or trunking. This is a requirement of BS 5467 and not the regulation. As it be described, under fault condition most the the fault current will flow through the cable and only a fraction through the armouring, this will produce circulating current, that may cause damage to cable. Read Paul cook commentary on IET regulations.