Home buyers electrical safety checks for Essex - Domestic Electricals Home buyers electrical safety checks for Essex - Commercail electricals Home buyers electrical safety checks for Essex - Industrial electricals

By Delta T Electrical your electrical contractors in Essex.


Delta T Electrical are able to carry out earth bonding upgrades in Essex and the surrounding areas.

Our team of fully qualified NICEIC registered Electricians, who are Part “P” certified work quickly and efficiently thereby minimizing the disruption to you and your home.

All of our local electricians hold both City and Guilds 2381/2382 and 2391 electrical qualifications and are fully experienced in the inspection and testing of commercial, industrial and residential premises and can advise you of any earth bonding upgrades necessary to keep you within the current regulations.

There are two types of bonding, Main Bonding and Supplementary Bonding.

Most properties built before 1991 generally have the bonding wired in 6mm or 4mm cable this is no longer compliant with the BS 7671 – Requirements for Electrical Installations IET 17th Edition Wiring Regulations if you would like your earthing system checked or earthing system upgraded please call our help desk or use the contact form to book an appointment.

If you need an electrician Essex is our home county and we guarantee to give all of our customer’s outstanding response times and an excellent service time after time.

Main Bonding

Main Bonding is used to connect the Water, Gas and Oil services to the Earth Terminal in or adjacent to your consumer unit. Connections are made on the metal pipes near the point at which they enter your home, i.e. The Main Bonding is normally connected within 600mm from your gas meter and water stop cock.

Main Bonding is there to protect you. A fault current will always try to find a path down to earth, literally to the ground. The current will always take the easiest path to ground; the idea of Main Bonding and Supplementary Bonding is to create an alternative path for the current to flow that is an easier path than along one of your heating pipes, along your arm, through your body, down your legs to the wet kitchen floor and to ground. By using a thick copper cable, you are creating a path that is more inviting to any fault currents and will divert any fault currents from your body or places where it should not go, as the current flows down to ground.

As long as the Water pipe, Gas pipe or Oil pipe, coming into your property are metallic, Main Bonding is compulsory in all circumstances even when the rest of the pipes in your house are plastic.

Main Bonding General Arrangement

General layout

Supplementary Bonding


Supplementary Bonding is used to connect together all metal pipes and possible circuits in a particular area. This area is typically the bathroom, or any other room containing a bath or shower. There may be cases when no supplementary bonding is required in the bathroom, i.e. all the pipes are plastic. There could be other circumstances also when no supplementary bonding is required but since the regulations and calculations involved would be impossible to translate into layman's terms, only a qualified electrician should make that decision.

When should Earth Bonding be upgraded?

The current wiring regulations BS 7671 – Requirements for Electrical Installations IET 17th Edition Wiring Regulations require upgrading of the earth cabling to your gas and water pipes when changing a consumer unit, or when carrying out any works that are part”P” notifiable, these cannot legally be carried out without the correct bonding being in place.

This is sometimes a simple job but can mean a lot of work depending on the location of your consumer unit, water stop cock and gas meter. The BS7671/IET Wiring Regulations are set out to ensure safe & reliable electrical installations. Delta T Electrical are able to carry out all earth bonding upgrades in Essex and the surrounding areas. And issue you with a Part “P” certificate.

Supplementary Bonding

For new installations or alterations / additions in a location containing a bath or shower, supplementary bonding will not be required if:
The disconnection times required by Section 411 of BS 7671 are met, and
All circuits are protected by RCD’s having the characteristics required by 415.1.1, and
The building has protective equipotent bonding in accordance with 411.3.1.2, and
All extraneous-conductive parts of the location are effectively connected to the protective bonding. (See note below)

Note: Regulation 415.2.2 states that where doubt exists regarding the effectiveness of supplementary equipotential bonding, it shall be confirmed that the resistance R between simultaneously accessible conductive parts and extraneous conductive parts fulfils the following condition:
R ≤ 50V  a for a.c. systems
By example, using a 30mA RCD (Required by 415.1.1)
R ≤ 50V  30mA = 1667 ohms

Where supplementary bonding is required, Regulation 701.415.2 requires that the protective conductor (cpc) of each circuit entering the room containing a bath or shower, be connected to the extraneous-conductive parts by local supplementary equipotential bonding conductors complying with Regulation group 544.2.
This is carried out to prevent the occurrence of voltages between any such parts being of such magnitude as could cause danger of electric shock. Ie current bonding is absent or inadequate.

Automatic Disconnection Of Supply

Where the protective measure ‘automatic disconnection of supply’ is used, additional protection by a residual current device, with a rated residual operating current not exceeding 30mA is required for all circuits in locations containing a bath or shower.

Practically this means that every circuit entering a bathroom should be protected by an RCD with a rated residual operating current not exceeding 30mA.

With a Continuity tester on the Ohms setting, test between each metal pipe that enters the bathroom (Extraneous conductive parts) and the circuit protective conductor (cpc) of each electrical circuit in the bathroom.

If the reading obtained is less than 1667ohms and all circuits are protected by 30mA RCD’s then no Supplementary Bonding is required.

If you are looking for a professional electrical contractor Essex Delta T Electrical are able to carry out testing and advise you what works will be necessary to make your electrical wiring installation compliant and safe.
Delta T Electrical are NICEIC registered domestic and commercial installers, Part “P” certified earth bonding upgrades in Essex and the surrounding areas are our speciality.

Call us today! Our help desk staff are waiting to assist you. See our number at the top of this page, or e-mail us via the request a quotation (Again, see top of this page) with your details and we will contact you shortly.