Posting a message to the forum will remove the above advertisement
  1. angel While you're here, would you mind checking out our Electrician's Insurance section to see if we could save you a few quid? - Specifically our Van Insurance Deals and Public Liability Insurance Deals. Thanks for supporting the forum! angel

    5% Discount from Electrical2Go.co.uk for ALL members! - Click Here

Building Control

Discussion in 'Business Related' started by carl9254, Dec 1, 2009.

Discuss Building Control in the Business Related area at ElectrciansForums.co.uk.

Thread Status:
Not open for further replies.
Please make sure you checkout our forum sponsors, many do discounts for members and, they keep the forum free to use.
  1. carl9254
    Offline

    carl9254 Electrician's Arms

    Hello, got my Elecsa assessment on 4th january, going to change the cu in my house and use that as assessment job, its simple as only 3 circuits, sockets, lights and shower. But shall i tell building control?? Elecsa said upto me, they dont request it but they will let building control know once ive done the job. it will cost £107 if i do.

    Also supply into house is TN-S so should get away with 6mm bonding which it looks like, but i just want to make sure by doing the adiabatic equation on page 128 of regs book, can anyone shed any light on easiest way of doing this??

    Thanks.
     
  2. adam.h
    Offline

    adam.h Regular EF Member

    I was told by building control to update to 10mm when I changed mine.
     
  3. roukel01
    Offline

    roukel01 Electrician's Arms

    Location:
    York(ish)
    also just a board change might not be enough for them to see, they usually like to see some installation work. I always try and take them to a full rewire
     
  4. carl9254
    Offline

    carl9254 Electrician's Arms

    Elecsa have said board change is fine and 6mm is fine aslong as supply is TN-S and that formulaworks out correct. Help on the formula would be good??
     
  5. Guest123
    Offline

    Guest123 Guest

    Hi.

    You cant use an adiabatic equation to size a bonding conductor, it's only for CPC's.
     
  6. carl9254
    Offline

    carl9254 Electrician's Arms

    So will 6mm be ok for a TN-S spply??
     
  7. Guest123
    Offline

    Guest123 Guest

    Well I would say as it's an existing scenario then you may be able to check the suitability of the existing bonding conductors by taking into account the PFC and size of the main fuse almost like doing an adiabatic but not really as it's not the main earthing conductor.

    Obviously you would need to know the PFC (by testing it), rating of main service fuse, time/current characteristics, and K value. All these can be found in the regs book.

    Probably best to install new 10mm for the assesment. You could show him that you used the equation to check, make you look good then too.
     
    Last edited by a moderator: Dec 1, 2009
  8. carl9254
    Offline

    carl9254 Electrician's Arms

    Im new to testing so just checking if done right.

    I got 1.37kA for my L-E reading. 1200A for my t reading and 143 for my k reading.

    Does that look right and will the answer be 11.49??

    Anyone?
     
    Last edited: Dec 3, 2009
  9. Guest123
    Offline

    Guest123 Guest

    Hi.

    I squared you have there.


    (T) comes from APP 3 of ol red. (K) comes from table 43.1 of ol red. (S) must be equal to or greater than the result of the sum.

    (S) = the square root of ((I) squared x (T)) divide by (K).
     
  10. carl9254
    Offline

    carl9254 Electrician's Arms

    So if i stick a 16mm in it will be fine.
     
  11. Guest123
    Offline

    Guest123 Guest

    Mate, you dont need to put in a 16mm bonding conductor 10mm is more than adequate.

    I didn't wat to do the calc for you as I believe working stuff out yourself is the best way of learning.


    Ok so the fault current is 1370A

    We'll assume a 0.1 disconnection as ol'red is in the van and it's belting down!!!

    The K value we'll take as 115.

    1370 squared = 1876900, x 0.1 = 187690

    187690 square root = 433.2

    433.2 / 115 = 3.76mm.
     
  12. carl9254
    Offline

    carl9254 Electrician's Arms

    Why did you do 0.1 disconnection and not 0.4?? Also why 115 for the k and not 143?? Tryin to learn :)
     
  13. Guest123
    Offline

    Guest123 Guest

    0.1 comes form the time current table in ol'red. The 0.4 value is the max value that circuits must disconnect under.

    With the fault current known you go to the graph in ol'red with a ruler and plot a line from the fault current you have to where it meets the time/current curve for your particular protective device. I dont know what you have so i was making an educated guess as the fault current you have, i think is past the curve for most devices so you assume a 0.1 disconnection.

    The 115 value is for 70 degrees thermoplastic cable with copper conductor.


    Right I went out in the MONSOON to get ol'red....turns out I was right so I got wet for nowt.:mad::p:D
     
    Last edited by a moderator: Dec 3, 2009
  14. carl9254
    Offline

    carl9254 Electrician's Arms

    Its a 1361 100A, so am i right in sayin it meets around the 0.3-4 mark??

    I took my last k reading from the 30 deg table, are most 70 deg??
     
  15. Guest123
    Offline

    Guest123 Guest

    Yes I think so too.

    Put 0.3 into the equation then and see what you get.:)
     
Loading...
Similar Threads - Building Control Forum Date
Building Control - Extract fan with filter? Electrical Forum Jun 20, 2018
Non notified Cu in a house and Building control The Electricians Arms Jun 18, 2018
Thread Status:
Not open for further replies.

Share This Page

Electricians Directory Post a Domestic Job Post a Commercial Job