Why get a periodic inspection and test?
You might say to yourself, “Why bother with an EICR?” and in all honesty, as an electrician, I understand. After all, you use your electrical installation every day of your life and have done for years, without issue. Your constant use of the lights, sockets, cooker or machines tells you that nothing is the matter and that there is unlikely to be. You could be right but as with all things, life takes its toll.
One of the things that scares a lot of people about electricity is that it is unseen. So are some of the degradations that can occur over time. Electricians use multi-meters to test whether the installation is functioning properly or degrading, from the resistance of the insulation which coats the live conductors, to the ability of your consumer unit to automatically disconnect the supply in the event of a fault, which could otherwise cost someone their life. Other problems are not naked to the eye, just naked to the untrained and require the expert knowledge of a competent person to be seen and rectified.
Listed below are some of the problems that electricians, like myself, find regularly in installations that are in service. The following faults are not an exhaustive list but are the common problems that change an EICR report from satisfactory to unsatisfactory. In a lot of instances, these codes are actually very simple to fix, requiring only the replacement of a single piece on the circuit. But its worth doing, to know that in the event something does happen, automatic disconnection does take place.
Faults on an EICR
Gaps and the Exposure of Live Parts
This is an immediately dangerous problem, where a person or animal can come into contact with something live. Missing blanks in a consumer unit is the classic example but this can also occur from badly broken sockets and switches, wires stripped of their insulation from friction or collision or holes in an enclosure which has not been blanked off. This is an automatic failure. Its the most severe kind of fault and yet, in most cases (the replacement of cables aside) they are the easiest to solve. These are the sorts of things that can be fixed on the day. There is not need to fail in most cases where simple things can be done for immediate improvement.
The IP Rating for any horizontal or flat surface, within an installation, must have a degree of protection no less than IPXXD or IP4X. This prevents small objects, such as cables with a cross-sectional-area of 1mm from being able to penetrate the containment or accessory.
In cases where live parts must be exposed, the opening must be no bigger than is necessary for correct function and operation, operatives must be informed by warning signs that the components must not be touched and suitable obstacles or barriers must be in place.
Lack of RCD Protection
Residual Current Devices (RCD) is a device which automatically disconnects the supply based on the imbalance of current draw between the live conductors – the neutral (black or blue colour) and the line conductor (brown or red). This sensitive form of protection is capable of detecting tiny imbalances in the milli-amp range. They are used for fault and additional protection, based on the application. If the installation does not provide enough current flow under fault conditions, they are used for fault protection, where fault current is restricted by high-resistance.
Most commonly they are used for Additional Protection, at a rating of 30ma. Limiting the amount of current that can flow, to 30ma, quickly disconnects the power, in the event of a fault, by 20ma below the threshold of current that can kill a person or animal. This type of protection is not provided by MCBs, which are actually for the protection of the circuit, not the protection of people.
Whatever the RCD is being used for, properties may not have any at all and in other cases, the mechanism inside the breaker has become broken and no longer operates. People typically neglect to push the test buttons of their RCDs, which causes them to become sticky or to malfunction altogether. This type of problem is always picked up on EICRs as they are crucial for the preservation of life under fault conditions.
Loose Connections
Loose connections can effect the disconnection time of a circuit by creating resistances higher than the maximum permitted for the type and rating of a given circuit breaker. Each breaker requires a certain amount of current to flow in order to trip instantaneously. For a Type B 32 amp miniature circuit breaker (MCB), roughly 160amps (5 times its current rating) must flow to meet the 0.4s disconnection time for TNS and TNC-S earthing systems. The maximum resistance at the farthest point on the circuit, for this breaker, according to table 41.3 of BS7671:2018 Amendment 2:2022, is 1.37 ohms. Each Breaker has its own maximum resistance value called the maximum permitted earth fault loop impedance and failure to meet this requirement means a failure to disconnect the circuit in safe timing.
Loose connections also pose the threat of fire, where arcing can occur, creating an excess of heat. Checking the tightness of the connections in your consumer unit is part of a periodic inspection.
Incorrect IP Rating of Equipment
IP stands for ingress protection. IP ratings are the degree of protection a given piece of electrical equipment is tested to. These rating are extremely important to follow because they tell us where they should and should not be installed, based on the external influences that the installation will have to cope with throughout its lifetime, such as whether for outdoor equipment or steam and the potential to be splashed on a bathroom.
Its common in older properties for the IP rating of bathroom fittings to be below the required rating of the regulations. Some items may also have been improperly installed, even though they are rated for the environment, essentially voiding the rating originally given to the accessory. Examples of these would be a pendant in a bathroom or an outdoor socket with a bulging gasket. Both of these can cause further deterioration or have the potential to eventually cause harm.
Cracked, Broken and Improperly Secured Accessories
Cracked and broken accessories can range in severity of code. A broken socket could be merely cracked or brandish exposed live parts. In either case the item needs to be replaces either to avoid future danger or to remove a current one.
The functionality of a circuit is also a concern at hand. Any defective switched should be replaced so that the circuit works properly for the customer and are picked up by an inspection. Should Items be loose, the likelihood that something breaks in the near future increases and increases the potential for live parts to be exposed in the future.
Insulation Degradation
The degradation of insulation is assessed using Meg-Ohms. This is the opposite of assessing the resistance of a connection because the desired outcome is completely the opposite. In this instance we want there to be no connection found, as opposed to the best connection possible. Voltage is pushed from the tester down the conductors, while two leads connect to two different connectors simultaneously. This assesses how strong the insulation is between them. In low-voltage systems, such as covered by this post and by the BS7671, circuits are tested at 500v, double the operating voltage, to ensure the insulation is capable of withstanding the voltage under its normal operation.
Old circuits typically have lower insulation resistance values indicative of a break down of the insulation. This helps us to gage whether the cables are likely to need replacing in the future. A good result would be 50 mega-ohms and up. The regs states that anything under 1 mega-ohm is to be considered a fault.
Lack of Earthing or Improper Size
The proper size of an earth is important for the safe disconnection of the supply. If the earth is incorrectly sized the conductor could heat to a degree that would damage the circuit or even cause a fire.
A lack of earth typically happens when a loose connection is bad enough to be a complete disconnection on a circuit. This is a cause for concern because the circuit-protective-conductor (CPC) is what provides the signal back to the MCBs and RCDs for them to trip. Without it, faults cannot be detected. The CPC is connected to the exposed metal work of the installation, defined as any metal work that is included within the electrical installation itself, that is exposed, such as a metal switch or cooker hood. These are the parts of the installation that you could touch and are the very part that must be earthed, if we are to provide you with any protection at all.
The extraneous metal work in the property. Pipes, and structural steel are considered extraneous because they are not a part of the electrical installation. These also need to be earth, in order to ensure that their equipotential does not differ from that of the exposed metal work. Should the potential differ and a fault from the electricity supplier occur, the exposed metal work could become live, undetected by the circuit protective devices in the consumer unit. If this occurs without bonding conductors present, on metal that is embedded in the earth, there is the potential for a person to simultaneously touch both exposed and extraneous metal, becoming a load. This would ultimately be fatal.
Lack of Ring Main Continuity
Ring mains are were originally introduced in war times, when materials were scarce. A single length of 2.5mm cable can only carry 26 amps clipped directly to a surface. When configured into a ring, where sockets are distributed evenly (see picture right) across a ring configuration of the same conductor, the load is evenly distributed across the two legs of the circuit. In the event that the continuity is lost all, of the load for the socket can flow through only one of the legs, making the breaker oversized for the current carrying capacity of the conductor. This leaves the circuit at risk of catching fire.
Incorrect MCBs, Fuses and Incompatible Makes and Sizes
All of these problems relate to the consumer unit, although, the incorrect sizing of fuses can also relate to other components. The bases of rewireable fuses and breakers, the busbar and the MCBS and the cover, are all designed to work together to create something both functional and safe. It is important that all components are of the same brand, to ensure compatibility. A lack of compatibility can create heat from improper connections and twisting of the busbar. The shape and size of components could also prevent proper closure of the enclosure.
MCBs and fuses must be sized correctly for the current carrying capacity of the cable. If a length of cable is capable of carrying 26 amps, it must not be put on a breaker that will allow more amps than it can carry. Otherwise the circuit would catch fire.