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

  • Replies 4 replies
  • Subscribers 37 subscribers
  • Views 458 views
  • Users 0 members are here
Options
You may also be interested in

Could/Should a uk domestic dwelling need a 10kA breaker in the future

Sergio Fernandez

Could/should a UK domestic dwelling need a 10kA breaker in the future, especially with the rise of high-power EV chargers or heat pumps, as these additions can increase potential fault currents (PSCC) beyond what a standard 6kA breaker can handle, making 10kA a safer, "future-proof" choice for new installations or upgrades, even if 6kA is often sufficient for basic setups



As always please be polite and respectful in this purely academic debate.





Come on everybody let’s help inspire the future

Parents
  • Sergio Fernandez said:
    as these additions can increase potential fault currents (PSCC) beyond what a standard 6kA breaker can handle,

    UK consumer units do have 6 kA breakers, but they must be suitable for a 16 kA prospective fault current! This has been the case for 10s of years, and this has been part of product standards for UK consumer units from the standards that preceded BS 5486.

    In current, and more modern, consumer units to BS EN 60439-3 and BS EN [IEC] 61439, the use of 6 kA breakers for a 16 kA prospective fault current is termed 'rated conditional short circuit current' and given the symbol Icc. This is tested for in the UK national annex to the relevant assembly standard for consumer units.

    For consumer units specifically, this is addressed in Regulation 536.4.201 of BS 7671:2018+A2:2022. The 16 kA conditional prospective fault current rating is applicable for public supplies with a 19.6 kA prospective fault current at the transformer, provided that the service cable length is at least 2 m in length.
    Equally importantly, the UK-specific testing for conditional prospective fault current is a key reason why you can only install devices approved by the manufacturer in a CU in the UK (see Regulation 536.4.203).

    Icc can also be specified for RCCBs and switchgear in other situations, provided the backup overcurrent protection meets the manufacturer's requirements. This is addressed in Regulations 536.4.2.3 and 536.4.2.4 of BS 7671:2018+A2:2022

Reply
  • Sergio Fernandez said:
    as these additions can increase potential fault currents (PSCC) beyond what a standard 6kA breaker can handle,

    UK consumer units do have 6 kA breakers, but they must be suitable for a 16 kA prospective fault current! This has been the case for 10s of years, and this has been part of product standards for UK consumer units from the standards that preceded BS 5486.

    In current, and more modern, consumer units to BS EN 60439-3 and BS EN [IEC] 61439, the use of 6 kA breakers for a 16 kA prospective fault current is termed 'rated conditional short circuit current' and given the symbol Icc. This is tested for in the UK national annex to the relevant assembly standard for consumer units.

    For consumer units specifically, this is addressed in Regulation 536.4.201 of BS 7671:2018+A2:2022. The 16 kA conditional prospective fault current rating is applicable for public supplies with a 19.6 kA prospective fault current at the transformer, provided that the service cable length is at least 2 m in length.
    Equally importantly, the UK-specific testing for conditional prospective fault current is a key reason why you can only install devices approved by the manufacturer in a CU in the UK (see Regulation 536.4.203).

    Icc can also be specified for RCCBs and switchgear in other situations, provided the backup overcurrent protection meets the manufacturer's requirements. This is addressed in Regulations 536.4.2.3 and 536.4.2.4 of BS 7671:2018+A2:2022

Children
No Data

Community Rules & Guidelines