Current operated ELCB

[ejmoore]

Went to quote for a job today,
Client currently has a 16th edition board with a current operated ELCB 230v 60amp 30mA main switch. He wants a socket radial circuit for his new extension.

My question is, is this switch 17th edition compliant. If I install the required circuit. I know it is the old form of RCD but as it covers the whole installation does it goes against reg 314

Would you recommend a CU change? Or install the required circuit! Bonding to water is present gas is plastic supply, does this still need Bonding.

Appreciate your replies.

 

[telectrix]

you can install a new circuit to that CU, but on the EIC i would note that the set up is prone to nuisance tripping of any circuit isolating all the installation. if you are unsure of bonding the gas. IR test from metal gas pipework to MET. if it reads > 22kohms, no need to bond it.

 

[Sintra]

Why would you need to replace the cu? Just install the new circuit and have it protected by the existing RCD. Test your addition job done.

 

[sparkdog]

Last time I tested one of those old main RCDs it gave faster trip times than I have seen on a modern RCD.

 

[ejmoore]

Thank you for your replies. It is very much appreciated.

I advised the client to upgrade his board because of future nuisance tripping. Client has extended his home. A sparky came in and installed 2 extra double sockets off the current ring final circuit which now exceeds 100 square meter allowed, he also FCU from the socket for lights for the new extension. Sparky wouldn't give him a Cert. He now wants the cables moving as he is ready to knock through to the extension. There is a spare way on the board with a 15 amp breaker, for a radial to power the current extension arrangement isn't really ideal is it?

So cu upgrade is recommended, do you agree?

 

[telectrix]

recommend if you wish, but don't try and pressure him into it. just explain the advantages.

 

[Silly Sausage]

Isn't that 100 sqm for an RFC just in the regs now for historical value only?

 

[ejmoore]

Yes, figure 15A iv. Historically 100sqm has been adopted. So any more than this, ie, 120sqm a new circuit should be installed?

 

[Engineer54]

Thank you for your replies. It is very much appreciated.

I advised the client to upgrade his board because of future nuisance tripping. Client has extended his home. A sparky came in and installed 2 extra double sockets off the current ring final circuit which now exceeds 100 square meter allowed, he also FCU from the socket for lights for the new extension. Sparky wouldn't give him a Cert. He now wants the cables moving as he is ready to knock through to the extension. There is a spare way on the board with a 15 amp breaker, for a radial to power the current extension arrangement isn't really ideal is it?

So cu upgrade is recommended, do you agree?

Are you sure about that, you'd have to go some to exceed a 100 sqm in a house installation. Unless the ring is covering both upstairs and downstairs as well as the kitchen. The average square meterage of an older house was around 140/150 sqm (for a 3 bed house), now it's more like 110 sqm metre rabbit hutches!! lol!!

Nothing stopping you changing the existing 15A MCB for a higher rated MCB!! Lighting can be extended from the existing downstairs lighting circuit, if it has a CPC incorporated in the existing cables...

 

[ejmoore]

The RFC is covering the whole house, upstairs downstairs kitchen and extension. I have measured the floor area.

Client hasn't had a EICR done in the last 20 years either. I dowt the last sparky even tested the circuit before or after additions. Seems my client is spending a lot of money modernising and improving his property. Be a shame it burned down from the lack of electrical saftey after all the hard work and cash he put into it.

 

[Engineer54]

The RFC is covering the whole house, upstairs downstairs kitchen and extension. I have measured the floor area.

Client hasn't had a EICR done in the last 20 years either. I dowt the last sparky even tested the circuit before or after additions. Seems my client is spending a lot of money modernising and improving his property. Be a shame it burned down from the lack of electrical saftey after all the hard work and cash he put into it.

That's fair enough then!! ...lol!!

Always the same i'm afraid, these sort of mindless people think far more about decorations than the families safety. By the time it dawns on them (if it ever does) they want everything installed without damaging all the ultra expensive decorations, which is 9 times out of 10, always an impossibility!! lol!!

 

[alanl]

The 100 sq M guide is due to the limitation of Zs and Volt Drop on such a circuit. If you calculate the sizes, and find they are within the VD and Zs values, then there is no problem.If it is a RFC, then R1 and R2 values can be measured to find out if the circuit will comply. Obviously any spurs will need to be checked individually.

 

[ejmoore]

Thank you for all your replies. I've learnt something today. That's what it's all about.

Cheers.

 

[MDJ]

. A sparky came in and installed 2 extra double sockets off the current ring final circuit which now exceeds 100 square meter allowed, , do you agree?

How do you know that?

 

[kingeri]

The 100 sq M guide is due to the limitation of Zs and Volt Drop on such a circuit. If you calculate the sizes, and find they are within the VD and Zs values, then there is no problem.If it is a RFC, then R1 and R2 values can be measured to find out if the circuit will comply. Obviously any spurs will need to be checked individually.

The 100m2 rule was more to do with heating, the thinking was that any more floor space would require more than the 30amps available on a single RFC.