Class B: Development by electricity undertakings

 

Class B permits specified development by statutory undertakers for generating, transmitting, distributing or supplying electricity. It covers some electric lines and associated equipment, communications lines, boreholes and work on operational land.

The Class excludes certain overhead electric lines that require consent under section 37 of the Electricity Act 1989. Other siting, size and temporary-work rules also apply.

 

Important exclusions and conditions

Check the 29 m³ threshold for apparatus chambers, the protected-land, 15-metre support and 1,000-metre line restrictions for electronic communications, and the volume, floorspace and height limits for building alterations. B(f) does not provide a general right to erect a new building.

Temporary diversion lines and borehole plant have six-month removal and restoration conditions. A building solely to protect plant under B(e) needs design and external-appearance approval before work begins. Read Part 15, Class B in full.

 

Electricity undertakings: changes from 21st October 2026

From 21st October 2026: SI 2026/1056, article 8, raises the Class B(a) apparatus-chamber threshold from 29 to 45 cubic metres for chambers at or above ground level or under a highway used by vehicular traffic. Where a chamber exceeds 29 cubic metres, it must not exceed three metres in height, be within five metres of a dwellinghouse, or be on an SSSI or European site. Above 29 cubic metres, any part on article 2(3) land triggers an application before work begins for a determination whether prior approval is required for siting and appearance. The other Class B rules remain.

The new procedure requires a written description, site plan, contact details and any required fee. The authority may refuse non-compliance or insufficient information. The procedure includes public notification, consideration of representations and relevant NPPF provisions, and a 56-day mechanism. Development must await written confirmation that prior approval is unnecessary, written approval, or expiry of the specified 56 days without notification whether approval is given or refused. Approved or submitted details must be followed unless otherwise agreed in writing.

This is a statutory-undertaker right. It is not a general permission for any landowner to build a substation. The five-metre dwellinghouse separation above is different from the ten-metre residential-curtilage separation for EV equipment housing under Part 2 Class E.

Legislation

Version note: the reproduced text below is the law before 21st October 2026. For development on or after that date, read it with article 8 of SI 2026/1056, which substitutes B.1(a)(ii), adds B.1(a)(iii) and B.2(1)(ba), and introduces the detailed procedure in B.2(2) to (11).

 

Class B – electricity undertakings

Permitted development

B. Development by statutory undertakers for the generation, transmission, distribution or supply of electricity for the purposes of their undertaking consisting of—

(a) the installation or replacement in, on, over or under land of an electric line and the construction of shafts and tunnels and the installation or replacement of feeder or service pillars or transforming or switching stations or chambers reasonably necessary in
connection with an electric line;

(b) the installation or replacement of any electronic communications line which connects any part of an electric line to any electrical plant or building, and the installation or replacement of any support for any such line;

(c) the sinking of boreholes to ascertain the nature of the subsoil and the installation of any plant or machinery reasonably necessary in connection with such boreholes;

(d) the extension or alteration of buildings on operational land;

(e) the erection on operational land of the undertaking of a building solely for the protection of plant or machinery;

(f) any other development carried out in, on, over or under the operational land of the undertaking.

Development not permitted

B.1 Development is not permitted by Class B if—

(a) in the case of any Class B(a) development—
(i) it would consist of or include the installation or replacement of an electric line to which section 37(1) of the Electricity Act 1989 (consent required for overhead lines) applies; or
(ii) it would consist of or include the installation or replacement at or above ground level or under a highway used by vehicular traffic, of a chamber for housing apparatus and the chamber would exceed 29 cubic metres in capacity;

(b) in the case of any Class B(b) development—
(i) the development would take place in a National Park, an area of outstanding natural beauty, or a site of special scientific interest;
(ii) the height of any support would exceed 15 metres; or
(iii) the electronic communications line would exceed 1,000 metres in length;

(c) in the case of any Class B(d) development—
(i) the height of the original building would be exceeded;
(ii) the cubic content of the original building would be exceeded by more than 25% or, in the case of any building on article 2(3) land, by more than 10%, or
(iii) the floor space of the original building would be exceeded by more than 1,000 square metres or, in the case of any building on article 2(3) land, by more than 500 square metres;

(d) in the case of any Class B(e) development, the building would exceed 15 metres in height, or

(e) in the case of any Class B(f) development, it would consist of or include—
(i) the erection of a building, or the reconstruction or alteration of a building where its design or external appearance would be materially affected, or
(ii) the installation or erection by way of addition or replacement of any plant or machinery exceeding 15 metres in height or the height of any plant or machinery replaced, whichever is the greater.

Conditions
B.2 Development is permitted by Class B subject to the following conditions—

(a) in the case of any Class B(a) development consisting of or including the replacement of an existing electric line, compliance with any conditions contained in a planning permission relating to the height, design or position of the existing electric line which are capable of being applied to the replacement line;

(b) in the case of any Class B(a) development consisting of or including the installation of a temporary electric line providing a diversion for an existing electric line, on the ending of the diversion or at the end of a period of 6 months from the completion of the installation (whichever
is the sooner) the temporary electric line is removed and the land on which any operations have been carried out to install that line is restored as soon as reasonably practicable to its condition before the installation took place;

(c) in the case of any Class B(c) development, on the completion of that development, or at the end of a period of 6 months from the beginning of that development (whichever is the sooner) any plant or machinery installed is removed and the land is restored as soon as reasonably practicable to its condition before the development took place; and

(d) in the case of any Class B(e) development, approval of details of the design and external appearance of the buildings must be obtained, before development is begun, from—
(i) in Greater London or a metropolitan county, the local planning authority,
(ii) in a National Park, outside a metropolitan county, the county planning authority,
(iii) in any other case, the district planning authority.

Interpretation of Class B

B.3 For the purposes of Class B(a), “electric line” has the meaning given by section 64(1) of the Electricity Act 1989 (interpretation etc. of Part 1).

B.4 For the purposes of Class B(b)—

“electrical plant” has the meaning given by section 64(1) to that Act; and

“electronic communications line” means a line which forms part of an electronic communications apparatus, (and both line and electronic communications apparatus have the meaning given in paragraph 5 of the electronic communications code set out in Schedule 3A to the Communications Act 2003 (the electronic communications code)).

B.5 For the purposes of Class B(d), (e) and (f), the land of the holder of a licence under section 6(1) of the Electricity Act 1989 (licensing of supply etc.) is treated as operational land if it would be operational land within section 263 of the Act (meaning of “operational land”) if such licence holders were statutory undertakers for the purpose of that section.

 

 

 

 

Explore GPDO Part 15

 

 

Page updated: 1st October 2026