old style rcd's

[sparkyork]

been to look at a job yessterday, one part is in a shop and the other works is in the main house. both buildings have seperate electricitry supplies.

shop electric works will be straightforward as ive got tt system with 10mm main earth bond and bond to gas in 10mm also got a 30ma rcd to use for the works.

other job tho needs his gas bond putting in so doing that first (he's with british gas so he reckons, who check his installation etc, i said i was suprised they didnt comment on the gas bond!!) anyway other works is just some lighting alterations etc. he's got an old wylex board which has one of the lighting circuits i need in it. i said im gonna have to protect any work i do via an rcd (logical place to do this is at the board), so im thinking of installing a small enclosure with rcd and extending lighting feed into this unit.
again this house is tt and is protected primarly buy an old earth leakage device, what rating are these things normally?? 100ma?? also main earth to electrode is 2.5mm so upgrading that aswell.

cheers and merry christmas

and also this old rcd has the connection to the electrode on it and the connection to the consumer unit. i want to install a seperate small consumer unit so what can i do with the earthing, is it acceptable to come from the old style rcd earth connection that goes to elcetrode and install a small earthing block so i can connect my new consumer unit earthing to this??

also are the old hollow earth spikes still acceptalbe are do they need swapping as well!!

 

[Shakey]

been to look at a job yessterday, one part is in a shop and the other works is in the main house. both buildings have seperate electricitry supplies.

shop electric works will be straightforward as ive got tt system with 10mm main earth bond and bond to gas in 10mm also got a 30ma rcd to use for the works.

other job tho needs his gas bond putting in so doing that first (he's with british gas so he reckons, who check his installation etc, i said i was suprised they didnt comment on the gas bond!!) anyway other works is just some lighting alterations etc. he's got an old wylex board which has one of the lighting circuits i need in it. i said im gonna have to protect any work i do via an rcd (logical place to do this is at the board), so im thinking of installing a small enclosure with rcd and extending lighting feed into this unit.
again this house is tt and is protected primarly buy an old earth leakage device, what rating are these things normally?? 100ma?? also main earth to electrode is 2.5mm so upgrading that aswell.

cheers and merry christmas

and also this old rcd has the connection to the electrode on it and the connection to the consumer unit. i want to install a seperate small consumer unit so what can i do with the earthing, is it acceptable to come from the old style rcd earth connection that goes to elcetrode and install a small earthing block so i can connect my new consumer unit earthing to this??

also are the old hollow earth spikes still acceptalbe are do they need swapping as well!!

Rich, sounds like you have an old ELCB (earth leakage circuit breaker), this could be a current operated type or even a VOELCB (voltage operated) - the VOELCB's are ...ahem.... REALLY dodgy.

A lot of ELCB's, even on domestic CU's can be as high as 500mA

You are quite right, it needs ripping out. Dont see a problem with using an MET external to the CU, as long as it has the usual 'Safety Electrical Connection.....etc) next to it

 

[sparkyork]

cheers shakey what needs ripping out the old spike??

 

[Spudmiester]

Is it a long black box with a yellow test button ? Could be an FVOD ......fault voltage operated device, they worked on voltage leakage, not current. There are a few of them around but they are donkeys years old.

Yes, rip it out and fit an RCD

 

[devon1]

old electrical equipment

Obsolete Chilton earth leakage circuit breaker



How does an VOELCB work?

VOELCBs work by connecting what is usually called the ‘earth wire’ (officially ‘the circuit protective connector’) of the final circuits to the main earth terminal via an electrical coil within the device. If enough current leaks from the ‘live wire’ (officially ‘phase’) to earth, it will produce a sufficiently high voltage across the coil to trip the isolator mechanism.

This automatic operation relies on three significant assumptions:
• That any leakage current passes to a circuit earth wire (or conduit, metal cable sheath, trunking, etc.) and not to earth via any other electrical conductor, such as a person
• That the earth wire or ‘circuit protective connector’ is continuous up to, and through, the VOELCB
• That the main system connection to earth at the consumer’s service board (and earthing rod, if relevant) is adequate and intact
If any of these is not the case - or even worse, if both are wrong - then the system can be lethal. VOELCBs are therefore no longer approved by the IEE Wiring Regulations .

What are the approved alternatives?

For earth leakage protection, the Regulations now recommend the use of a residual current device (RCD), which detects earth leakage by comparing live and neutral currents and disconnecting the circuit if they are different. Any difference implies some fault connecting live or ‘phase’ to earth.

A VOELCB can be recognised as follows:
• It has a On/Off toggle switch and a Push to Test button (like an RCD)
• It has two earth wire connections (an RCD has none)

Any surviving VOELCB (voltage-operated device) should be replaced with an RCD (residual current device) under the guidance of a qualified electrician registered by NICEIC (National Inspection Council for Electrical Installation Contracting). Otherwise people may be at risk, and it is highly likely that the insurance cover of your job will no longer be effective.