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Topic Title: VOELCB
Topic Summary: Data required for Periodic Report Schedule
Created On: 06 September 2009 01:34 pm
Status: Read Only
Linear : Threading : Single : Branch
 VOELCB   - Phased - 06 September 2009 01:34 pm  
 VOELCB   - stureid - 06 September 2009 01:45 pm  
 VOELCB   - sparkingchip - 06 September 2009 01:54 pm  
 VOELCB   - sparkingchip - 06 September 2009 02:11 pm  
 VOELCB   - CarlCosby - 06 September 2009 02:35 pm  
 VOELCB   - Phased - 06 September 2009 02:51 pm  
 VOELCB   - spinlondon - 06 September 2009 04:34 pm  
 VOELCB   - sparkingchip - 06 September 2009 04:49 pm  
 VOELCB   - sparkingchip - 06 September 2009 04:51 pm  
 VOELCB   - alancapon - 06 September 2009 05:36 pm  
 VOELCB   - stureid - 06 September 2009 05:58 pm  
 VOELCB   - perspicacious - 06 September 2009 06:13 pm  
 VOELCB   - stureid - 06 September 2009 06:27 pm  
 VOELCB   - Phased - 06 September 2009 08:10 pm  
 VOELCB   - Paul1966 - 06 September 2009 08:49 pm  
 VOELCB   - sparkingchip - 06 September 2009 09:04 pm  
 VOELCB   - Paul1966 - 06 September 2009 09:20 pm  
 VOELCB   - sparkingchip - 06 September 2009 09:40 pm  
 VOELCB   - sparkingchip - 06 September 2009 09:42 pm  
 VOELCB   - Paul1966 - 06 September 2009 09:57 pm  
 VOELCB   - sparkingchip - 06 September 2009 10:00 pm  
 VOELCB   - spinlondon - 06 September 2009 09:05 pm  
 VOELCB   - Paul1966 - 06 September 2009 09:45 pm  
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 06 September 2009 08:49 pm
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Paul1966

Posts: 1538
Joined: 21 December 2004

The limitation option seems reasonable if you're going to be pulling the whole board apart and replacing with a modern RCD.

But for the record, here is the relevant section on testing from the 14th edition, 1966. Appendix 6, Earth tests & measurements; part 3, Test of earth-leakage circuit-breakers (as required by Regulation E.5):

For the purpose of this test a voltage not exceeding 45 volts, obtained from a double-wound transformer connected to the mains supply, shall be applied across the neutral and earth terminals (or neutral and frame terminals of a voltage-operated earth-leakage circuit-breaker) and the circuit-breaker shall trip instantaneously. The transformer shall preferably have a short-time rating of not less than 750VA (see Figures 2 and 3).

When, in accordance with the requirements of Regulations D.10-13, cross-bonding to other services is carried out in an installation where a voltage-operated earth-leakage circuit-breaker is provided, this may result in a direct earth connection of low impedance being introduced in parallel with the path through the earth-leakage circuit-breaker. Thus an increased value of earth-leakage current would need to flow before the circuit-breaker came into operation, and in some instances the cross-bonding may well remedy the deficiency which originally gave rise to the need for the earth-leakage circuit-breaker. These effects are not harmful; it is common practice to use the best solid earth available (e.g. suitably spaced earth electrodes) in parallel with an earth-leakage circuit-breaker. The circuit-breaker would still be effective in preventing the exposed metalwork of the installation from rising to a dangerous voltage.


Of course, those parallel paths must not affect the reference earth electrode to which the coil of the ELCB is connected, as required by regulation D.26:

The earth electrode of any voltage-operated earth-leakage circuit-breaker shall be placed outside the resistance area of any parallel earth which may exist, for example where a water heater is installed. If by sub-division of the earthing system, discrimination in operation between a number of voltage-operated earth-leakage circuit-breakers is to be afforded, the resistance areas of the associated earth electrodes shall not overlap.


The V/O-ELCB testers generally had a double-wound transformer with a tapped secondary, so one side was just linked to the neutral and by using test jacks or a switch you could apply 10, 20, 30, 40, or 50 volts to the earth of the socket supplying the tester.
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