AnswerID: 209583 Submitted: Sunday, Dec 10, 2006 at 11:56
Brian, an RCD (Residual Current Device) - also known as a safety switch and previously known as an Earth Leakage Circuit Breaker (ELCB) operates by measuring any in-balance in current flow between the active and neutral conductors. The standard RCD will operate when the in-balance (fault current) reaches or exceeds 30 milliamps. The in-balance current would be flowing through an alternate means back to the source of supply (through the earthing system).
The issue with portable power sources is the lack of an earthing system and the lack of M.E.N (Multiple Earth / Neutral bonding). This means that a fault current path through may not exist meaning that the RCD will not operate unless the fault is integral with the supply cables or the connected equipment.
So, in answer to your question, an RCD would improve the safety but will not work in the same circumstances as it would in a fixed LV (240 volt) installation.
Note, If RCDs are to be fitted to a switchboard, it is best to use individual MCB / RCDs (main circuit breaker RCDs) to each circuit requiring protection.
Disclaimer - Electrical work undertaken on fixed LV grid
supplied installations is required to be undertaken by an authorised person.
Cheers Tony, REC7359
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