TT 100ma Rcd + earth electrode??

[impactes]

Hi al,l I am working on a tt system at present. I am going to be a adding a new d/b which will be ran from an existing board which has a 30ma main switch, controlling 1 other circuit i need to change the main switch to 100ma and the 1 circuit its controlling will need changing to a 30ma rcbo as its controlling outside power and lights.
The reason i need to change the main switch is because i will be using 30ma rccbs at new db.

The question i need answering is does the 100ma rcd need to be time delayed? If so the problem i have is that its a hager board and cant seem to find a time delayed rcd from them, so is there an alternative manufacture which i will be able to use? or do they do 1 and am i just not looking in the right place?.

Also would it be advisable to put in new earth electrode to supply new d/b current Ra 25.8 ohms.

Cheers

 

[Guest123]

The 100mA RCD would need to be time delayed to provide discrimination.

Also the Ra of 25.8 is good so I would be happy to leave as is.

 

[impactes]

The 100mA RCD would need to be time delayed to provide discrimination.

Also the Ra of 25.8 is good so I would be happy to leave as is.

Hi thanks for reply do you know if hager do a time delayed rcd or if an mk or wylex would fit ok.

Thanks

 

[Sintra]

Hi thanks for reply do you know if hager do a time delayed rcd or if an mk or wylex would fit ok.

Thanks

Hager make them. Have a look

 

[Guest123]

Hager make them. Have a look

Same page i just found.

 

[impactes]

Thankyou very much guys was looking for ages couldn't find them.

Much appreciated

 

[impactes]

Hi sorry to jump back in with another question.
But was just thinking does the cable that i will be running to the new d/b not need to be 30ma protected, as once i change the rcd it will only be 100ma protected.

Many thanks

 

[Guest123]

Depends what cable it is and how it's installed. I assumed you'd already taken that into account.

 

[impactes]

Depends what cable it is and how it's installed. I assumed you'd already taken that into account.

Yeah apologies didn't think till afterwards, was just trying to avoid any nuisance tripping. Its a 16mm T&E and is ran in a boxing (approx 8 metres) straight from existing d/b and then is clipped direct about 600mm to new d/b. I assume from this it will need 30ma protection?.

Your advise is much appreciated
Many thanks

 

[Guest123]

Is it at any point buried in the wall i.e chased in and plastered over???

For the 600mm it is clipped direct, to what is it clipped direct to...wall surface???

If it is within a purpose made boxing and surface clipped or in mini trunking then the additional 30mA protection is not required.

 

[impactes]

Is it at any point buried in the wall i.e chased in and plastered over???

For the 600mm it is clipped direct, to what is it clipped direct to...wall surface???

If it is within a purpose made boxing and surface clipped or in mini trunking then the additional 30mA protection is not required.

No it is not chased into the wall and is clipped to the surface. So will be able to change it.

Many thanks