Polarity Testing

<h2>What polarity testing verifies</h2>
<p>Polarity testing confirms three things:</p>
<ol>
<li><strong>Line conductors are connected to line terminals</strong> of all accessories, switches and equipment</li>
<li><strong>Single-pole switches interrupt the line conductor only</strong> — never the neutral</li>
<li><strong>Correct polarity is maintained throughout the installation</strong></li>
</ol>

<h2>Why polarity matters</h2>
<p>Reversed polarity at a socket means equipment plugged in has live and neutral transposed. Switches on appliances interrupt the neutral rather than the line — leaving the appliance live when apparently switched off. A switch in the neutral of a lighting circuit leaves the lampholder live when the light is off — severe shock risk when changing bulbs.</p>

<h2>Dead polarity testing</h2>
<p>Carried out before energising using a continuity tester:</p>
<ol>
<li>Connect one lead to the line terminal at the consumer unit</li>
<li>Connect other lead to the line terminal at each accessory in turn</li>
<li>A low reading confirms the line conductor is correctly connected throughout</li>
<li>Repeat for neutral and CPC</li>
</ol>

<h2>Live polarity testing</h2>
<p>After energising, use a voltage indicator (GS38 compliant) to check:</p>
<ul>
<li>230V between line and neutral at each accessory</li>
<li>230V between line and earth at each accessory</li>
<li>Near 0V between neutral and earth</li>
</ul>

<h2>Key exam points</h2>
<ul>
<li>Polarity is tested DEAD then confirmed LIVE — both in the CRIPPER sequence</li>
<li>C2 code on EICR for reversed polarity at accessories</li>
<li>A switch in the neutral is potentially dangerous (C2)</li>
<li>Edison screw lampholders must have line on the centre contact</li>
</ul>