Lighting Circuits Without an Earth
Work in progress.
Many lighting circuits are still in use that have no earth or conductive protective core (cpc). Whilst the rewiring of these circuits is the preferable solution, for many people the cost of installation and redecorating can be prohibitive.
If a rewire is not an option then the following steps should be taken for safety reasons
1. Class I (metal) light fittings and accessories should be replaced with Class II (plastic) fittings
2. Resistance test. The circuit should be tested between the line conductor (line and neutral connected together) and the earth terminal of the consumer unit. The resistance should be at least 1 Megohm
3. RCD protection. It is advisable to have 30mA RCD protection on lighting circuit that have no cpc.