If polarity is not correctly determined there may be a risk of electric shock during maintenance procedures. For example, if you isolate or switch the neutral of a circuit via a single-pole circuit breaker or switch, it would appear that the circuit is dead where in fact it is still live. This test will verify that all the switches installed in the system are connected in current carrying conductor and not in neutral. (This is done with the supply connected, therefore carried out at a different stage then the above three).Ī test that creates a circuit using the phase conductor and the single pole device in question, breaking the circuit when operating the device, means that the reading on the instrument will change, and thus confirming that that device must be connected in the phase conductor. The polarity of the mains supply must be correct, using an approved voltage tester.All polarities of socket outlets (ring & radial) must be verified.The phase conductor must be connected to the centre terminal of an Edison screw lamp holder (with the exception of E14 & E27 lamp holders, these are European and occasionally crop up in the exam).All single pole devices (fuses, switches and circuit breakers) are connected in the phase conductor only.There are 4 different scenarios that require a polarity test, these are:
To ensure this, polarity test is done at each relevant point. This simple test is just as important as all the others, and many serious injuries and electrocutions could have been prevented if only polarity checks had been carried out. We cannot simply trust that the electricians have connected things up the right way everyone makes mistakes, even if it’s your own work. Since ac installations consist of a Live and a Neutral conductor, it is extremely important that these conductors are connected the right way around, within all electrical accessories such as wall sockets or plugs. The purpose of a polarity test to ensure that all single pole devices (fuses, switches and circuit breakers) are connected in the phase conductor only. Similarly, it’s important to confirm that switches are located in the line conductor not the neutral conductor. For example, for an Edison-screw lamp holder, it is important that the line conductor is connected to the centre terminal and the neutral conductor is connected to the outer conductor. In the context of electricity installations, a polarity test is used to confirm the correct connection of the line and neutral conductors. Most multimeters, including digital multimeters, can do this. Regarding alternating current in the context of an ac supply, a polarity test is done to ensure that the line and neutral conductors are connected the correct way around at, for example, electrical sockets, Edison-screw lamp holders, etc. In an alternating current (AC) circuit the two poles alternate between negative and positive and the direction of the current (electron flow) reverses periodically. In a direct current (DC) circuit, current flows in one direction only, and one pole is always negative and the other pole is always positive.
Polarity in electrical terms refers to the positive or negative conductors within a dc circuit, or to the Line and Neutral conductor within an ac circuit. Electrical polarity (positive and negative) is the direction of current flow in an electrical circuit. Current flows from the positive pole (terminal) to the negative pole. Electrons flow from negative to positive.
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