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 10 replies
  • Subscribers 34 subscribers
  • Views 3595 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

How to interpret the 512.1.5 of BS 7671

eizo

Maybe I’m confused･･･.

I regret to say that I cannot understand the meaning of Regulation 512.1.5. 

Is it possble to interpret the second pargraph and note 3 of Rgulation 512.1.5 as follows? In principle equipment such as circuit breakers must be connected to thermoplastic insulated cables because their maximum operating temprature is 70° C. But the equipment is also allowed to connect to 90° C thermosetting insulated cables provided that when deciding conductor sizes of the cables, a table from Tables 4D1 to 4D4 of Appendix 4 is refered instead of a table from 4H1 to 4H4. 

Any guidance or suggestion will help me.

Thank you.

Parents
  • 0

    Yer wires must not get hot and make yer switchgear hot as well, as that could damage the switchgear etc. A temperature limit of 70 degrees C is set.  The tables referred to are for copper conductors or aluminium conductors. All of those tables referred to are for 70 degree C rated cables.

    The 70 degree C limit is met if 70 deg C tables are used for a 90 degree C cable of similar construction. (Last sentence of the second paragraph).

Reply
  • 0

    Yer wires must not get hot and make yer switchgear hot as well, as that could damage the switchgear etc. A temperature limit of 70 degrees C is set.  The tables referred to are for copper conductors or aluminium conductors. All of those tables referred to are for 70 degree C rated cables.

    The 70 degree C limit is met if 70 deg C tables are used for a 90 degree C cable of similar construction. (Last sentence of the second paragraph).

Children
  • 0 in reply to Zoomup

    Thank you for your reply.

    I will read the last sentence of the second paragraph and condider your whole reply.

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