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 20 replies
  • Subscribers 31 subscribers
  • Views 2253 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

adiabatic equation - 2.5 2c SWA

Stewart Mason
I don't get involved with adiabatic equations all to often, hence I'm a bit rusty! I'm trying to calculate the R1+R2 for a 2 core 2.5mm SWA. Obviously the R1 is the easy bit, I'm struggling with the SWA as the R2.  I saw a link to a table on the old forum but I can't find it now. Any ideas?


Thanks Stewart
Parents
  • 0

    Stewart Mason:

    With what Graham has said I'm slightly confused. 


    So with a Ze of 0.35, a 16A 60898 type B, and 30 metres of 2c 2.5mm using the SWA as the earth would this comply? 


    Thank you. 




    If you mean with the adiabatic equation for protection against fault current, then yes... quite simply, there's a note to the bottom of table D7, and para 1 of D3,  in GN1 that says so.


    No calculation required. unless it's an unusual installation method, or a different than usual ambient temperature.


    Will it provide fault protection as well as overload protection? That would require a knowledge of R1+R2, but with a B16. Again, assuming no correction factors apply, you're well in at 30 m, you could probably go over 3 times as far and still achieve 0.4 s disconnection times - but I think volt-drop will limit you to about 45 m with 2.5 mm2 conductors in any case.

Reply
  • 0

    Stewart Mason:

    With what Graham has said I'm slightly confused. 


    So with a Ze of 0.35, a 16A 60898 type B, and 30 metres of 2c 2.5mm using the SWA as the earth would this comply? 


    Thank you. 




    If you mean with the adiabatic equation for protection against fault current, then yes... quite simply, there's a note to the bottom of table D7, and para 1 of D3,  in GN1 that says so.


    No calculation required. unless it's an unusual installation method, or a different than usual ambient temperature.


    Will it provide fault protection as well as overload protection? That would require a knowledge of R1+R2, but with a B16. Again, assuming no correction factors apply, you're well in at 30 m, you could probably go over 3 times as far and still achieve 0.4 s disconnection times - but I think volt-drop will limit you to about 45 m with 2.5 mm2 conductors in any case.

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