Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 6 replies
  • Subscribers 32 subscribers
  • Views 3709 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Split concentric ccc?

Farmboy

Hi all



Basically, what ccc table, if any, in apdx 4 would be used for split concentric? I've had a look on the old forum but couldn't see a definitive answer, so sorry if I've just missed it.



The scenario is an existing domestic installation has an approx 7 metre run of what appears to be 25mm2 cable running from the external meter box, under the floor, to the internal CU, on a 100A main fuse, with no switch fuse.



The installation method is awkward to determine because the cable comes up internally through the floor screed, making it seem to be buried under the concrete floor. However, there also appears to be an approx rough/faint 100mm circular pattern around the cable which makes me think there may be a duct (probably brown plastic drainage pipe) just below the surface, but can't be sure, could just be the way the screed was smoothed around the cable.



So, if there's a duct, will that satisfy reg 522.8.10 (probably no cable making though), so the concentric can remain? But if there's no duct, should it be disused/replaced because the cables protective earth only surrounds 1/3 of the cable?



So if the cable can remain, what ccc and size of switch fuse?



Thoughts please - apart from run the other way ?


F


Parents
  • 0

    davezawadi:

    I agree Alan, but that does not make an existing installation "dangerous", but simply non-compliant. Sheathed cables are not "double insulated" (class 2) but you know that! I don't like this split con tails install, but I also think that ripping up a concrete floor is not very useful, on the information provided. Does SWA make this any safer, I rather doubt it. Also I presume the DNO connected these tails to the meter, are you saying that they did not? There is an answer, and that is to note the deficiencies in the EICR notes, then it is up to the customer to decide to change it if they wish. BS7671 does not say anything about the alleged problem, and so the EICR should reflect this.




    Sorry, it's not an eicr. I was attending the property to look at something else and noted this cable. There's a cct to put in to the CU and thinking about the existing setup must be adequate, so thinking about installing a switch fuse, which led on to the cables installation method.


    I'd already seen the pdf mapj1 posted, and saw that the installation method wasn't listed, which led to the question of ccc for the cable under/in concrete, and applying 0.9 rating factor for buried cables, hence the question about ccc and size of switch fuse.


    Regards


    F

Reply
  • 0

    davezawadi:

    I agree Alan, but that does not make an existing installation "dangerous", but simply non-compliant. Sheathed cables are not "double insulated" (class 2) but you know that! I don't like this split con tails install, but I also think that ripping up a concrete floor is not very useful, on the information provided. Does SWA make this any safer, I rather doubt it. Also I presume the DNO connected these tails to the meter, are you saying that they did not? There is an answer, and that is to note the deficiencies in the EICR notes, then it is up to the customer to decide to change it if they wish. BS7671 does not say anything about the alleged problem, and so the EICR should reflect this.




    Sorry, it's not an eicr. I was attending the property to look at something else and noted this cable. There's a cct to put in to the CU and thinking about the existing setup must be adequate, so thinking about installing a switch fuse, which led on to the cables installation method.


    I'd already seen the pdf mapj1 posted, and saw that the installation method wasn't listed, which led to the question of ccc for the cable under/in concrete, and applying 0.9 rating factor for buried cables, hence the question about ccc and size of switch fuse.


    Regards


    F

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines