Power transmission and distribution networks
- 29/29.240/29.240.01 Power transmission and distribution networks in general
- 29/29.240/29.240.10 Substations. Surge arresters
- 29/29.240/29.240.20 Power transmission and distribution lines
- 29/29.240/29.240.30 Control equipment for electric power systems
- 29/29.240/29.240.99 Other equipment related to power transmission and distribution networks