Earthing and Bonding snags and solutions NICEIC

Lightning protectionsystemsLightning protection systems should be

connected to the Main Earthing Terminal

(MET).

Snag 13Instances are occasionally encountered of

lightning protection systems not

connected to the Main Earthing

Terminal of the electrical

installation.

MARCH 2006 (2nd edition)

SolutionThe lightning protection system

must be connected to the MET

of the electrical installation by

main bonding conductor(s)

complying with Section 547

(Regulation 413-02-02 refers).

Where there is a lightning

protection system, due account

must be taken of the

recommendations of BS 6651

(Regulation 541-01-03 refers).

The lightning protection system

itself is, however, excluded

from the scope of BS 7671 by

Regulation 110-02-01.

It is advisable that the exact

positions of bonding connec-

tions are determined by the

lightning protection system designer, due to the complexity of the requirements of

BS 6651. Normally, the connection should be from the down conductor of the

lightning protection system closest to the MET of the electrical installation, by the

most direct route available. Bonding connections should not be made without

consulting the designer of the lightning protection system, the system maintenance

contractor or other competent person.

Bonding connections to a lightning protection system are normally made outdoors,

and may involve conductors of different shapes and dissimilar metals. Accordingly,

special consideration should be given to the requirement of Regulation 526-01-01 for

electrical connections to provide durable electrical continuity and adequate

mechanical strength, and those of Regulation Group 522-05 regarding measures to

avoid corrosion.

snags and solutions NICEIC

snag 13

Earthing and Bonding snags and solutions NICEIC

Electricity cable

Water

Gas

Service pipes

Insulator

External down conductor

Main EarthingTerminalFor cavity walls provide sealed tube

Test joint

Lightning protectionearth terminationnetwork

G

Main equipotential bonding conductor

Generally, the means of connection should be discussed and agreed with the lightning

protection system designer and installer. It is often best for the actual making of a

connection to the system to be to carried out by the lightning protection installer,

although it is still the electrical contractor’s responsibility to see that this is done

satisfactorily.

Exceptionally, for reasons of safety, lightning protection system designers may advise

that a main bonding connection should not be made to a lightning protection system. In

such circumstances, the consequent departure from Regulation 413-02-02 must be

recorded on the Electrical Installation Certificate and reference made to the last

sentence of Regulation 120-01-03. The departure must be drawn to the customer’s

attention. This is permissible only where the electrical contractor has requested the

main bonding connection be made, and has obtained the lightning protection system

designer’s written objection to the connection being made on grounds of safety.

MARCH 2006 (2nd edition)

Regulation 110-02-01 (part of)

The Regulations do not apply to the following installations:

(ix) lightning protection of buildings covered by BS 6651.

Regulation 120-01-03 (part of)

Any intended departure from these Parts requires special consideration by the

designer of the installation and shall be noted on the Electrical Installation Certificate

specified in Part 7.

Regulation 413-02-02 (part of)

In each installation main equipotential bonding conductors complying with

Section 547 shall connect to the main earthing terminal extraneous-conductive-parts

of that installation including the following:

(vi) the lightning protective system.

Regulation 526-01-01

Every connection between conductors and between a conductor and equipment

shall provide durable electrical continuity and adequate mechanical strength (see

Other mechanical stresses, Regulation 522-08).

Regulation 541-01-03

Where there is also a lightning protection system, reference shall be made to

BS 6651.

snags and solutions NICEIC

snag 13