RCD / Safety Switch Nuisance Tripping
This is a frustrating problem which will probably become slightly more common as we use a greater array of electronic appliances in both our homes and offices.
Firstly, we’d like to give you an overview of how a safety switch works so that you can understand the cause and effect. A safety switch measures the amount of current leakage to earth from the wiring and appliances within your premises. When the leakage reaches the factory-set level, the safety switch operates and switches off the power supply to that circuit or circuits.
If an appliance develops a fault and excess current leaks from this appliance, the safety switch senses this additional leakage and if it exceeds the factory-set level the safety switch operates and the power is disconnected.
In all electrical installations there is some leakage present. This is normal and in most instances very low. The amount of leakage increases with the number of appliances connected. The condition of the wiring in your property will also affect and possibly add to the level of leakage. All appliances leak a very small amount of current and when you have a number of appliances each leaking this small amount, then the accumulative value of all of these appliances are added together to produce a larger value.
If the normal day-to-day leakage is high, due to the amount of electronic equipment and/or the condition of your electrical installation, then the safety switch will be close to tripping most of the time. All it will take is for a very small disturbance on the Western Power Network and this will cause a safety switch in this situation to trip.
Western Power does carry out capacitor bank switching each day and has done so for many years. With the advent of safety switches and the greater percentage of electronic equipment in the home and office in recent years, the occasional customer does experience nuisance tripping of safety switches. This is caused when the leakage in your safety switch is higher than desirable and is combined with Western Power switching operations that produce a small transient. This transient will not normally affect any customers, except in an installation where the leakage is excessive, making the safety switch susceptible to nuisance tripping.
A simple test to confirm the cause of the problem would be to unplug all of your electronic equipment (it is not sufficient to just turn them off) for the time period when the tripping occurs, in most cases you would then notice that the tripping of the safety switch would cease.
The problem is within your premises and is activated by Western Power switching operations that have always occurred.
There are several solutions that you can have an electrician carry out for you to rectify this problem and we have listed them for you in order of reliability.
- Have each individual circuit of your installation individually protected by combination RCD/MCB's - highly recommended.
- Have an additional safety switch installed and have the circuits 'split' over the two safety switches. This will not always guarantee success with every installation.
- Have the existing safety switch replaced with a 'delayed trip' safety switch. This unit delays the tripping function an additional 10 milliseconds and will usually correct the problem.
Some caution needs to be exercised here, because if most of the leakage is only on one particular circuit within your installation, then consideration may need to be given to splitting the existing wiring into two or more circuits to reduce the leakage on any particular circuit.
The advent of many more electronic appliances, especially computers and UPS units, combined with the much wider mandatory use of safety switches within all installations these days, has made this problem a little more prevalent in recent years.
These three alternatives are only suggestions and you should talk to a suitably qualified electrician as what best suits your particular installation.
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