Tech Help
Domestic Help
With many years of experience in domestic electrical installations and maintenance, we can provide you with all the help you need for all your domestic electrical work.
Whether you need help with a fuse box replacement or a tripping MCB we offer the expertise to provide you with a solution to work around all your electrical applications.
Please scroll down for information on common domestic electrical faults.
Fuse box replacement
Many older fuse boxes use a piece of fuse wire which is designed to burn out under load. The wire needs replacing every time they are overloaded or become britle and break due to everyday usage.
If you have an old fuse box with re-wireable fuses then you could benefit from an upgrade to a new modern consumer unit (fuse box) with circuit breakers instead of fuse wire and RCD’s for additional protection.
A Residual Circuit Device (RCD) protects by constantly monitoring the current flowing in the live and neutral wires supplying a circuit or an individual item of equipment.
Under normal circumstances, the current flowing in the two wires is equal.
When an earth leakage occurs due to a fault in the circuit or an accident with the equipment, an imbalance occurs and this is detected by the RCD, which automatically cuts off the power before injury or damage can result.
A Circuit Breaker (MCB) has two automatic disconnect devices, as well as magnetic coil which detects overcurrent it also contains a bimetallic strip which the current passes through. The two metals are chosen so that as they heat up in response to the current flowing, as the temperature rises the strip curls, if a large enough current flows disconnection occurs. This thermal type of circuit has the added benefit of detecting even quite small overloads.
The ease of re-tripping MCB’s as opposed to re-wiring a blown fuse wire and the additional protection a new consumer unit gives you far outweigh the cost of replacement.
Powerlec Electrical and Testing is currently offering a full Fusebox replacement for £350, This includes:
Commercial Help
Help with your commercial electrics when you need it most.
Worried about the strain of office equipment on your electrics? Thinking of installing new lighting or sockets in your commercial property? Then call us, we are on hand for all manner of commercial technical questions and problem solving and can help you get the most from your electrics, no matter what your business.
Commercial electrical testing
The Electricity at Work Regulations 1989 or EAWR are statutory and state:
- All systems shall at all times be of such construction as to prevent, so far as is reasonably practicable, danger
- As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger
The only way to ensure your electrical installation is safely maintained would be to carry out an Electrical Installation Condition Report, formerly known as a Periodic Installation Report. Which in most cases are required 5 yearly.
Another option would be to test approx. 20% of the installation every year which can be preferred by companies who cannot isolate all of the electricity at any one time.
Many people/organisations dismiss electrical testing as a necessity as it is not statutory. This is a common miss-conception although it is not directly wrong.
The Electricity at Work Regulations 1989 or EAWR are statutory and state;
- (1) All systems shall at all times be of such construction as to prevent, so far as is reasonably practicable, danger.
- (2) As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger.
All electrical installations deteriorate with age and use. They should therefore be inspected and tested at appropriate intervals to check whether they are in a satisfactory condition for continued service. Such safety checks are commonly referred to as ‘periodic inspection and testing’ now known as an Electrical Installation Condition Report.
A periodic inspection will:
- Reveal if any of your electrical circuits or equipment are overloaded
- Find any potential electric shock risks and potential fire hazards
- Identify any defective electrical work
- Highlight any lack of earthing or bonding
The inspection takes into account all the relevant circumstances and checks on:
- The adequacy of earthing and bonding
- The suitability of the switchgear and controlgear. For example, an old fusebox with a wooden back, cast-iron switches, or a mixture of both will need replacing
- The serviceability of switches, sockets and lighting fittings. Items that may need replacing include: older round-pin sockets, round light switches, cables with fabric coating hanging from ceiling roses to light fittings, black switches and sockets mounted in skirting boards
- The type of wiring system and its condition. For example, cables coated in black rubber were phased out in the 1960s. Likewise cables coated in lead or fabric are even older and may well need replacing (modern cables use longer-lasting pvc insulation)
- Sockets that may be used to supply portable electrical equipment for use outdoors, making sure they are protected by a suitable residual current device (RCD)
- The presence of adequate identification and notices.
- The extent of any wear and tear, damage or other deterioration.
- Any changes in the use of the premises that have led to, or may lead to, unsafe conditions
As it is a requirement that electrical systems installed in places of work comply with the The Electricity At Work Regulations 1989, More and more companies are putting in place people and policies that deal with the electrical testing and other Proactive Maintenance Programs to create a safe ,viable and profitable environment for their staff.
MCB Trip
If an MCB trips this could be an indication either that the circuit has been overloaded or that a short circuit (fault) has occurred somewhere in the circuit.
Before resetting the MCB it is important to attempt to identify what has caused it to trip. I would advise to switch off any appliances connected to the circuit or switch off any switches which may have been on.
Before attempting to reset the MCB I would advise turning off the Main Switch, this will isolate all the electricity to the circuits. Reset the MCB by flicking the lever, up is on, down is off.
Finally return the Main Switch back to the on position.
If the MCB immediately resets itself once power is restored, then a fault is still occurring.
Overloading
Overloading can be a fairly easy problem to solve, it is caused when too many appliances on one circuit are used which exceeds the rating for that circuit, causing the fuse to trip. The easiest solution is to be careful not to use too many appliances or fittings at the same time.
Short Circuit
If you are certain the circuit is not being overloaded then the next step is to inspect all the light fittings, switches, sockets, and appliances using the blown circuit.
Firstly make sure the circuit is off using an appropriate tester. If you are not confident doing this yourselves then we recommend you to call in the experts.
Look for damaged cables or scorched areas.
If you still can’t find any problems then it is time to give us a call.
| Prior to year | Description |
| 1948 | Lead sheathed cables are commonplace. These have rubber insulated, tinned copper conductors and an outer sheath of lead. The conductor insulations is prone to deterioration as for TRS cables and due to the outer sheath being lead these conductors must remain properly earthed. |
| Early 1950s | Non-standard (5 and 15) amp socket outlets. These socket outlets accept plugs that may or may not have an earth pin, commonly a round pin. |
| 1955 | Circuits had a fuse in the neutral conductor as well as the phase conductor. In the event of a short-circuit there is a 50% chance of the neutral fuse operating, not disconnecting the phase conductor automatically and leaving the circuit in a dangerous condition to the unwary. |
| Early 1960s | Tough Rubber Sheathed (TRS), Vulcanised Rubber Insulation (VRI) cables were used. These are easily recognisable by their black exterior. The rubber insulation can become dry and brittle due to overload or excessive temperature. These cables should be left undisturbed until replacement and today are well out of their safe working life. |
| 1965 | Accessories on wooden mounting blocks were commonplace. This practice was discontinued due to the possible initability of the materials used. |
| 1966 | 14th edition Published No requirement for CPC’s at lighting circuits. If encountered rewiring of the lighting circuit or provision of local earthing is required unless all fittings are of a non-metallic type not requiring an earth to prevent indirect contact (electric shock). Water or other service pipes as means of earthing an electrical installation, no requirement for main uipotential bonding conductors to service pipes.The 14th edition introduced this requirement though they were often undersized or absent. During the 1980’s new regulation was introduced requiring the sizing of main equipotential bonding conductors to be much larger than before? For most dwellings the minimum size should be 10mm2. |
| 1972 | Imperial sized cables. Conductors may be single stranded or have 3, 7 or more strands. These can be difficult to recognise, however it should be noted that imperial cable types might have tinned conductors giving them an unfamiliar colour. |
| Mid 1975 | Metric sized 2.5 twin and earth had a CPC of 1.0mm. Due to the common fuse type being BS 3036 at this time it was soon realised that the reduced CPC wouldn’t allow adequate disconnection times in a 32 Amp ring main. |
| 1977 | Green coloured protective conductors or sleeving instead of green/yellow. Green coloured tape or sleeving must be replaced with green/yellow sleeving when making a re-connection. |
| 1981 | 15th edition Published No requirement for supplementary equipotential bonding. Today the minimum size of conductor is 4mm2 with no mechanical protection Earth Leakage Circuit Breakers. Apart from normally being marked ELCB this device can be recognised by its two separate earthing terminals, one for the load and one as a means of earthing, normally to a rod. The drawback with this device is that parallel paths may render it inoperable. No RCD protection for socket outlets likely to supply portable equipment outdoors. In 1981 it first became a requirement that at least one socket outlet would have RCD protection, this was soon found to be inadequate. Today all socket outlets of 32Amps or less, which may reasonably be expected to supply portable appliances for use outdoors, must be protected by an RCD of not more than 30ma. |
| 1986 | Concealed cables outside of permitted zones in walls. When working in a dwelling dating before the latter part of the 1980’s extreme care should be taken when drilling in to walls, floors or ceilings. A cable stud detector could be used to reduce risk of damaging badly routed cables. |
| 1992 | 16th edition published (yellow) Supplementary bonding connected back to the consumer unit. This didn’t provide localized equipotential earthing and so this practice was discontinued in 1992-1993. |
| 2001 | 16th edition republished (blue) Changes to requirements for supplementary bonding in bathrooms. Regulation 601-04-01 requires that the protective conductor terminals of each circuit supplying Class I and Class II electrical equipment in zones 1, 2 or 3, and extraneous-conductive-parts in these zones, are all connected together by local supplementary equipotential bonding conductors complying with Regulation Group 547-03. This means that installations after this date should not only have supplementary bonding between extraneous conductive parts but should then be connected to the CPC of each separate circuit in zones 1,2 or 3 i.e. shaver socket, lighting circuit, shower etc allowing equal potential with the DB earth. This requirement was published in 2001 and came in to force 1st of Jan 2002. |
| March 2004 | 16th edition republished (brown) Non-Harmonized Cable Colours Standard. Phase - Red, Neutral - Black in standard twin. 3 core colours - Red, Yellow, and Blue, as were 3 phase system conductors. Installations on site after the 31st of March 2004 and before the 01st of April 2006 could use either standard cable colours or harmonized but not both. |
| April 2006 | Standard Red and Black cables could be used.After the 1st of April 2006 harmonized cable colours only were permitted for electrical installations. |
