Joining cables.

[Mellykp1]

Hello everyone I am new to this site and always a bit worried about coming on forums for advice because I've heard people say about people being sarcastic, nasty or putting you down because you have asked a silly question, I'm an audio visual engineer of a small company and they put me on one of those month long courses a few years ago and past all the exams but I never class myself as an electrician but also I have never had anyone to turn to for advice or help so I just refer to the internet and wiring regs for help but this time I have bit the bullet and joined this site. Here is my question I did some work in a school last year and I joined a number of cables together the old black and red and extended them with brown and blue, I crimped all my joins and tidyly put them back in to the metal conduit, the conduit is earthed. My boss just spoke to me and said they had the system inspected and it was said that the inspector was surprised that the joints were in metal conduit and not pulled out and joined in a plastic box but upon looking at the regs it states that "where a connection is made in an enclosure the enclosure shall provide adequate mechanical protection and protection against relevant external influences". That's on page 107 ref 526.7 I may be reading this wrong and misunderstood it can anyone clarify this is it wrong to do joins in metal conduit that is earthed or should I have done all the joins in a plastic box.
thanks for listening.
Mel

 

[GMES]

Mel welcome to the forum and despite what you've heard we don't bite.
The only thing we ask of new members is that they are as transparent and clear as possible and provide all relevant info so the members can assist you correctly.

 

[Mellykp1]

I don't mind being transparent lol and I understand thanks for the welcome

 

[andyb]

Hi Mel

By metal conduit do you mean metal trunking?

 

[davesparks]

Joints can be contained in metal trunking or conduit boxes with no problem. It would be better to fit a metal box to the trunking to house the joint, especially if there are more than one or two cables to be joined.

In my opinion the idea of fitting a plastic box to steel trunking to make connections would be bad practice. If a box is needed it should be a steel one to afford the same protection as the trunking does.

 

[Mellykp1]

Yes metal trunking it was about 3 inches square

 

[Mellykp1]

That's great thanks dave sparks

 

[markc123]

upon looking at the regs it states that "where a connection is made in an enclosure the enclosure shall provide adequate mechanical protection and protection against relevant external influences". That's on page 107 ref 526.7

You're using the wrong regs book ...

 

[Mellykp1]

How am I using the wrong book it's the red book bs7671 IEE wiring regulations 17th edition, which book do you suggest I should be looking at

 

[Guest77]

Hello everyone I am new to this site and always a bit worried about coming on forums for advice because I've heard people say about people being sarcastic, nasty or putting you down because you have asked a silly question, I'm an audio visual engineer of a small company and they put me on one of those month long courses a few years ago and past all the exams but I never class myself as an electrician but also I have never had anyone to turn to for advice or help so I just refer to the internet and wiring regs for help but this time I have bit the bullet and joined this site. Here is my question I did some work in a school last year and I joined a number of cables together the old black and red and extended them with brown and blue, I crimped all my joins and tidyly put them back in to the metal conduit, the conduit is earthed. My boss just spoke to me and said they had the system inspected and it was said that the inspector was surprised that the joints were in metal conduit and not pulled out and joined in a plastic box but upon looking at the regs it states that "where a connection is made in an enclosure the enclosure shall provide adequate mechanical protection and protection against relevant external influences". That's on page 107 ref 526.7 I may be reading this wrong and misunderstood it can anyone clarify this is it wrong to do joins in metal conduit that is earthed or should I have done all the joins in a plastic box.
thanks for listening.
Mel

Home : Oxford English Dictionary

 

[Darkwood]

Hi melly the regulations has seen a few ammendments since the publication of that book we had a green one after the red and we have now just introduced the Yellow book with the third ammendment.

 

[Guest77]

How am I using the wrong book it's the red book bs7671 IEE wiring regulations 17th edition, which book do you suggest I should be looking at

The right one for starters Mel.

 

[Mellykp1]

Lol Oxford English dictionary great answer I'll remember you for more great advice. :uhoh2:

 

[Mellykp1]

Thanks darkwood I'll get the boss to by the new book thanks for your help.

 

[tigerpaul]

The cable joints would be better taken into an enclosure to be fair. You need to consider the environment it is in, what the likely hazards are and then you can decide if plastic or metal will be suitable.

 

[Guest77]

Joining it in the trunking is IMO rough, a metal box bushed to the side of the trunking with din rail connectors inside a much better option.

 

[Leesparkykent]

As the singles are in trunking could they of been replaced from point to point?

 

[Mellykp1]

Thanks tigerPaul but in reference to my question is it wrong to join cables and put them back in metal trunking.

 

[tigerpaul]

I'm not searching through my books now, but I doubt if it is "against the regulations", but it is not best practice.

 

[Mellykp1]

Unfortunately they could not be replaced point to point and thanks everyone for your advise I know now to put a box on the outside and put all the joins in there.