Electrical Supplies, Distribution Boards and PAT Testing Safety!

My Husband is mad at me :(
Apparently I have written about all sorts on here (including kitten care tips) and yet not promoted his business at all! He feels left out (Aww bless). So I said if he writes an article out, I'll post it. I also said he could consider it his Christmas present from me, but that idea was just met with a scowl and some muttering!
Dave (Hubby) has his own electrical business. He specialises in fitting distribution boards, rotary isolators, consumer units, and all that type of complicated machinery, as well as a PAT Testing arm. PAT testing is explained more below, but basically checks electrical equipment (mainly office items like kettles, printers PC's etc) to ensure they are safe for use. Having these two divisions works well, as it means he gets some good commercial contracts from the supplies, and then the PAT testing element ensures continuity with the clients and a long relationship with repeat purchases. Clever isn't he?
Anyway, over to Dave.

First, thanks to Mel for letting me near her precious blog! I want to write an article on the basics of distribution boards and why it takes a professional company to install them. So here is ‘All You Need To Know About Distribution Boards‘.

The distribution board is also known as a panel board, breaker panel, consumer unit or service panel. The distribution board is part of a building electrical wiring and has the role of splitting the building’s main power feed into smaller subsidiary circuits. The main power feed is divided through the use of protective fuses, circuit breakers or residual-current devices in a common enclosure. The distribution board enclosure also houses the main switch.

A distribution board with RCD

The circuit breaker or residual-current devices are usually placed in two columns. Each row of circuit breakers or residual-current devices is connected to a different phase of the electrical power supply. This is because mains AC electrical power supply comes in split phases i.e. it has more than one energized conductor. This means each pole contact of a circuit breaker or residual-current device is connected to a different phase. This prevents overloading of any of the phases in the AC power supply. The front facing part of the distribution board is always a dead-front, which means no energized(live) parts of the electrical circuitry are exposed. This reduces the risk of electrocution.

A fuse is usually a copper wire placed in a small ceramic cylinder, which melts when a large electrical current flows through it. An increase in the electrical current can be due to an overload or short-circuit. Therefore, a fuse needs to be replaced every time there is an overload or short-circuit.

Circuit Breakers
A circuit breaker is an automatic switch that is designed to protect a subsidiary circuit from an overload or short-circuit. The circuit is designed to detect a sudden increase in electrical current which causes it interrupt current flow. Unlike a fuse which is used only once, a circuit breaker can be manually or automatically reset to allow continued current flow.

The circuit breaker makes use of mechanically stored energy in springs or compressed air tubes, to separate electrical contacts breaking current flow. The sudden increased current can also flow into an electromagnetic relay that then separates the electrical contacts. The electrical contacts are designed to withstand repeated electrical discharge arcs. The contacts are made with copper, copper alloys, and silver alloys.

Residual-Current Devices
The residual-current device has an almost identical physical appearance to the circuit breaker. However, it mode of operation is slightly different. The residual-current device is designed to constantly monitor current flow in the energized conductor and the ‘neutral’ conductor. The main power grid alternating current electrical power supply¬†carries electrical energy in a ‘live’ conductor while the ‘neutral’ conductor is used to complete electrical circuits.

By monitoring and comparing the electric current flowing in and out of an electrical circuit, the residual-current can detect current leakage. Current leakage is usually caused when a part of an electrical circuit becomes grounded. This can be due to a short-circuit or accidental grounding when a person touches a live part of the circuit. Once the current leakage is detected the residual-current device interrupts electrical power flow preventing a potentially fatal electric shock.

3 Phase Distribution Boards

For all the people related to electronics, a 3 phase distribution board may be a relatively simple term. However, for laymen, it can be defined as a component of electric supply system which divides the incoming and the outgoing power supplies. It is called by numerous names like an electric board, panel board, breaker box, fusion board and many more. When we talk of a 3 phase distribution board, the first and foremost thing we should be aware of is about its installation.


Installing a 3 phase distribution board can be quite a challenge. It requires a lot of technical skill and a big responsibility too. There are certain steps that need to be followed for the successful installation of this board. Also, proper care should be taken while checking the incoming and outgoing supplies as there can be chances of you being affected with the passing current. First ensure you get an industry standard distribution board, such as the ones Cudis sell. They must be approved by an official body for setting electrical standards, such as IET.

STEP 1:  

The location has to be determined by the incoming power supply, as in the case of most distribution boards. Also, it has a fully wired integral meter. While fixing it to the wall at a certain height, it is necessary to use your spirit level.


Once the board is fixed on the wall, the unit can be populated or rather activated with the outgoing devices. The technical aspects have to be up to the mark, for example, the bus bar stubs should be correctly inserted into the box clamps and should be tightened correctly. In order to ensure maximum IP protection, fit the full form blanks to any unused outgoing supplies.


In case you are using brown cable, you need to label the incoming cable to differentiate one from the other. This happens only in the case when there are three-phase incoming supply cables. The cables can be labeled as black, brown, grey, from left to right in a way it can be clearly seen. The interface kit should be used to mark the trunking to ensure protection against the sharp edges.


It should be carefully observed that the connecting link is dropped out and not connected while connecting the incoming neutral to avoid the swift passage of current which can be harmful to the human body.


Make sure that the cables are well dressed and secured with the cable ties. Also ensure that the radius bend is neat and there are no sharp bends in the cable. It makes it easier to identify and test circuits when they are labeled nicely and clearly enough.


All the sample tests should be carried out before energizing the flow of current. If the integral meter board is being used, open the blade fuses before the insulation resistance tests are performed. Also ensure that the main neutral link is connected.


Lock the door for security where the board has been heightened or enclosed. A door barrel lock can easily work in this case.


After all the live tests have been carried out successfully, ensure that all the circuits remain identifiable. Check if you have a schedule of circuits attached on the inner side of the door and also see whether the certificates and user documentation are authentic.


The installation of a 3 phase distribution board requires a proper streamlined method. As such the order of the steps is of immense importance. It is in the best interest if a certified professional overlooks the entire installation to negate the chances of the current being overflowed at certain places.

So as you can see from the above, it is a highly technical job. I have recently visited multiple places where someone not qualified, but with a little electrical knowledge has attempted to install a distribution board, or make alterations to one, themselves. Some of them have been downright dangerous! As they say ‘A little knowledge can be dangerous’. Call in a professional company for ANY electrical work!

Also, when working in an office, do me a favour. You see the plugs for all your electrical items? Do they have a green sticker on them? Those things are called PAT test labels. They show when the items was tested, when the next test is due, and hopefully a ‘pass’ symbol (if not, and it’s a red ‘Fail’ label, do not use it!)

If there is no label – get on to your boss now! Whilst they aren’t technically a legal requirement having a PAT done, it can lower your business insurance by having yearly checks done, it is safer, and the Law does state that an employer is responsible for ensuring electrical items are safe – PAT testing can help towards fulfilling that obligation.

A PAT test will involve someone with a relevant qualification coming to test all the appliances in your office. They will compile a report of the tests and results, and can even fix minor issues for you on site (we at Safety-PAT do this free of charge).

So get in touch today for a PAT test or if you know someone who needs some professional electrical engineering carried out!

Thanks for reading, have a great Christmas and 2015! Mel & Dave

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