Surge Protection Switchboard
Cris Luczak
Today's increased reliance on very sensitive electronics makes surge protection an important topic for Switchboards listed to UL891. The Insurance Institute for Business & Home Safety study found that $26 billion dollars was lost due to non-lightning power surges. In addition, there are about 25 million lightning strikes in the US each year that cause between $650M to $1B in losses according to the Insurance Information Institute, State Farm.
NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed. This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E.Being a key component of most of the power distribution network throughout an entire facility, the surge protection will provide 2 critical functions: protection of the switchboard itself and first layer of protection for that actual equipment and branch panels feeding from that switchboard.
Choosing the right surge protective device (SPD) and protective circuit breakers involves considering a wide range of parameters related to types of SPDs, circuit breaker arrangements, and risk assessment.
Use European HD 60364-5-53, for example. Some countries make it compulsory to use this standard when considering surge protection for big and/or highly sensitive buildings like industrial facilities, hospitals, and data centers.
Otherwise, bear this rule of thumb in mind: always install a Type 2 surge protection. If the distance between the surge protector and the equipment to be protected is greater than 10 meters, then add a Type 2 or Type 3 SPD, close to the load to be protected.
You should choose a circuit breaker according to the short circuit current of the building where the SPD is installed. For example, a disconnection circuit breaker with a short-circuit breaking current lower than 6kA is suitable for a residential building. For an office, it is usually 15kA or 20kA.
But determining matches is a delicate business, many parameters need to be considered while selecting the external short-circuit protection (Breaking capacity, Lightning current withstand, Coordination with upstream protection)
Hello Victor,
The explanation is given in the Wiki-EIG/ Chapter J 6.4 :
-installation.org/enwiki/Detailed_characteristics_of_the_external_SCPD
We compare tripping curve MCB versus Fuse . MCB is the best protection against impedant short circuit (An impedant short circuit dissipates a lot of energy and should be eliminated very quickly to prevent damage to the installation and to the SPD.)
BR
Our businesses and homes are filled with many items that are susceptible to power surges. This includes anything with a microprocessor, like computers, TVs and kitchen appliances. Power surges, even low-level fluctuations, can damage sensitive electronic equipment. Take steps to protect these items.
Fluctuations in voltage of the electricity that flows into your business or home, sometimes called a power surge, occasionally interfere with normal equipment operation. A surge can stem from inside, occurring when equipment with a motor starts up or shuts down.
A surge also can be caused by external factors resulting from a lightning strike or something interacting with a power line.
Type 1: Full-building surge protection. Also known as service entrance surge protectors, these are the strongest type of protection devices. A qualified electrician can install these permanently connected, hard-wired devices near the utility pole where electricity enters your main breaker panel. Type 1 devices help filter the power that enters your building, ensuring external factors are mitigated before entering your internal power system.
Type 2: Branch or load circuit protection. Type 2 devices are the main protection system for all low-voltage electrical installations. A qualified electrician can install these permanently connected, hard-wired devices in each electrical switchboard to help limit transient voltage.
Type 3: Point-of-use or device-specific protection. Power strips, the most commonly seen type of surge protectors, are Type 3 devices. Some are able to redirect and protect against medium surges, while others only guard against a mild surge. Look for these features when purchasing power strips:
An uninterruptible power supply (UPS) device can be placed between the electrical receptacle and the computer (or other electronic equipment) to isolate it from an outage. When the UPS senses a change in voltage or a power outage, it switches to battery backup. The batteries provide time to save information and shut down. Some models use software that can close and save your files before safely shutting off the computer. This is typically referred to as an unattended shutdown.
MGE recommends a UPS be applied to electronic equipment that could be adversely affected by power problems. These include PCs, PLCs, phone systems, etc. Choose the type of UPS by how critical the equipment is that you need to protect.
All the power in your house runs through a switchboard, which receives the power from the street and then distributes the power throughout the rest of your home. As such there are very strict electrical regulations about how it must be set up. All residential switchboards must have a main switch that provides overload protection and both overload and RCD (safety switch) protective devices on all other circuits including power, lighting and electrical appliance circuits (eg. A/C, cooktop, oven and solar).
The switchboard enclosure is typically a plastic or metal enclosure which houses the protective devices. It is the location where all the electrical circuits originate before the cables are distributed throughout the building.
The main switch isolates the electrical supply to the whole installation so that it can be turned off for servicing or maintenance. It also provides overload protection for the mains cables (on newer switchboards) so that it will trip if the cable is drawing too much power.
Over-current circuit breakers provide protection from overloading the cables. This means that if too much power is being drawn through a circuit the circuit breaker will trip to prevent the cable from overheating and starting a fire. This can happen when too many appliances are turned on at once, a cable is damaged causing a short circuit, or water enters an appliance causing a short circuit.
Residual Current Devices (RCDs), otherwise known as safety switches, are designed to protect people and animals against electric shocks. Without safety switches, your switchboard provides absolutely no protection against electric shock. Safety switches are the only device that provide protection to humans, and the electrical system in your home is unsafe without them.
RCDs will trip when there is leakage current. This occurs when electricity flows through a person during an electrical fault or other fault scenarios. All residential circuits are required to have safety switch protection, including power, lighting, ovens, cooktops, A/C and hot water units.
An earth electrode is a metal stake that is driven into the ground on the outside of your home and it is then wired directly into your switchboard. This provides protective earthing/grounding for your electrical system which is vital to the safe operation of all the electrical equipment in your home.
Older homes that were built before the 1990s utilised a form of protective earthing called an equipotential bond. This involved joining the electrical earthing onto the metal plumbing pipes in the house that then run underground.
The risk with relying solely on equipotential bond earthing is that the protective earthing system can be accidentally completely disconnected by a plumber if the old metal pipes are removed, replaced or modified. Plumbers do not have electrical testing equipment to make sure that they are not interfering with the electrical earthing systems. This means the safety devices in your switchboard may not operate correctly.
With a complete switchboard upgrade, Kenner Electrics will ensure you have an up-to-date earthing system which includes an independent earth electrode. The electrode will make sure that the protective devices in the switchboard operate correctly to protect your family and anyone else who might be working on your house!
Anytime the electricity supply voltage goes above what an appliance is rated to, there is a risk of damage to the appliance. A surge protector provides protection against an over-voltage fault that can damage appliances. Surge protection can be installed in your switchboard to ensure expensive appliances are kept protected if there is a surge on the power lines.
Surges are an over-voltage event which could be caused by lightning, HV injections (where High Voltage Lines come into contact with low voltage power lines that connect to homes and businesses during a storm or an accident) and other events caused by electricity distribution. While Australia has a very reliable and safe electrical distribution system, accidents and faults are more common than you think.
Arc Fault Detection Devices (AFDD) offer the latest form of electrical safety equipment that is becoming popular in Australia. An AFDD provides protection against electric arcing which could cause a fire.
While Arc Fault Detection has been common in America for many years due to the power distribution differences in America (they have 110V power which is more susceptible to high current arcing than the 240V power used in Australia and much of the rest of the world), it has taken a while for Australia to see the benefits.
Principally, AFDDs provide protection against a fire starting due to an arc fault. Arc faults can be caused by older wiring with damaged insulation, or broken/damaged conductors and terminals that have higher resistance due to corrosion or wear and tear (like switches, older power points and old fuse holder contacts). Electric arcs are hot enough to melt metal so they can very quickly start a fire in home if they are left undetected.
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