A fault refers to something happening in your electrical distribution system that is not part of the normal running operation of the system. Generally, it involves electrical current flowing somewhere that we don’t want it to go. You might also hear it referred to as a short circuit.

Let’s liken an electrical system to an irrigation system. A hose is connected to a main water supply (via a tap). Let’s say this irrigation system is watering two sections of the yard so it has a splitter at the tap and then it has two hoses that each have their own on/off valves located at the sprinklers.

We can draw the following parallels:

Connection to water utility = Connection to electrical utility

Splitter = Electrical Switchboard Bus

Tap = Main Switch at switchboard

Hoses = Electrical Cable

On/Off Valves = Switches / Circuit Breakers

Sprinklers = Load (equipment needing the power)

Let’s examine the scenario where your main tap is in the on or flow position and your sprinkler valves are off. Your hoses will have water in them and be under some pressure. Now consider someone accidentally cutting through one of the hoses with a spade. The water will flow as fast as it physically can to escape through the broken end of the hose. Its only limitations will be the pressure available from the water utility and the size of your pipes/hoses. This is an unwanted (or fault) condition.

Consider the same setup in our electrical system – the main switch is on, but our switches to loads are off. Our electrical system will have “potential” or voltage in that it has potential for current to flow. This is much like the pressure in our hose. If a cable is damaged and comes into contact with the ground or another cable in the system, electrical current will flow at the maximum capacity that the electrical utility and the cables will allow. Electricity on the loose can be a little more concerning than water escaping from a garden hose. Unlike a garden hose system, where water could continue to flow at maximum rate and do little (or no) damage to the hose, taps and fittings; electrical current flowing through equipment at high rate can very quickly cause damage due to rapidly increasing temperatures. Even though a fault is an unwanted situation, we still need to plan for it and ensure that if it does happen, equipment won’t be further damaged.

Faults could occur anywhere in your system, though some are more likely than others. Just as your splitter, tap, valves or even sprinklers could spring a leak, all the components of the electrical system need to be studied as potential fault locations and the effects of those faults happening, considered. That’s where a fault study comes in.

If you’re responsible for an electrical system and something goes wrong (a person is injured or worse), you may have to answer to government authorities who will be investigating the incident. In Australia & New Zealand, it is a requirement for circuits greater than 800 amps to undergo electrical system studies such as Protection Coordination and Arc Flash Analysis; the pre-requisite for both of these being a Fault/Short Circuit Study.

AS/NZS 3000 (The Wiring Rules) is an Australian and New Zealand standard which is mandated by most legislation so that means it is the law.

If you want to find out more about whether you need a fault study for your site, get in touch with SPRK today.