RCD's on farms

[Jimmyb]

Hello, was wondering what people thought about a cable supplying the farm buildings, i need to replace the cable so it now be a 16mm swa from service head area, across the garden and into the 1st shed, i was look ar brb and saw reg 705.411.1 (iii) which says all other circuits require 300ma rcd protection will this apply to the sub main cable or not.

many thanks

 

[malcolmsanford]

What earthing arrangements have you at the service head ?

If you have a TN arrangement you could in fact protect the SWA and do without the RCD protection for it.

 

[netblindpaul]

You may you may not!

 

[Jimmyb]

What earthing arrangements have you at the service head ?

If you have a TN arrangement you could in fact protect the SWA and do without the RCD protection for it.

That was my plan but the reg states : 'in all other circuits, RCD's with a rated residual current not exceeding 300ma'

My thoughts was if i was using a rcd to protect for the sub main cable then it had to be 300ma or less but im not as its tn system but it does say in all other circuits so still not sure.

 

[yellowvanman]

For what its worth, this is my interpretation:

For circuits with sockets less than 32A - 30mA RCD
For circuits with sockets greater than 32A - 100mA RCD
Everything else (including sub mains) - 300mA RCD

My guess, is that this is the RCD level for fire protection - farms usually store flammable materials

 

[Jimmyb]

Thats what i thought as well just didnt want to have to buy a rcd to replace the switch fuse as it isnt on the farm until the cable enters the shed and then its goes striaght into the board.

 

[Deleted member 26818]

What do you mean, 'it's not on the farm until the cable enters the shed'?

 

[Jimmyb]

it across the garden which is seperate to the farm

 

[malcolmsanford]

If you look at reg 705.414.4 it classes residences and all other buildings as a farm installation,

I'm sorry jimmy I did make mistake about the RCD I was thinking of construction sites mate, and yes for any circuit in Agi you need to have RCD protection, sorry mate I took you down the wrong road there

 

[shocking_eg]

so even with the earthed outer sheet of the armouring you still need to rcd protect the sub main ?

 

[JD6400]

so even with the earthed outer sheet of the armouring you still need to rcd protect the sub main ?

Will probably get shot down now , but the way i interpret it is yes .
We always bring the main tails in to a 100 to 300 ma s type before anything else, as yellowvan man put it, is how i see it too .
The type S is for discrimination , and we always TT all boards in the installation !
Would like to hear others opinions on how we do it ?

 

[Jimmyb]

Will probably get shot down now , but the way i interpret it is yes .
We always bring the main tails in to a 100 to 300 ma s type before anything else, as yellowvan man put it, is how i see it too .
The type S is for discrimination , and we always TT all boards in the installation !
Would like to hear others opinions on how we do it ?

I normally bring the sub main from house and then tt everything from subboard onwards with s type 100ma but look like im gona have to start with rcd at source.

Do you also need to rcd protect the house with 300ma or less rcd, if yes how long has it been like that because ive not come across any yet

 

[Deleted member 26818]

300mA was introduced with the 17th, prior to this 500mA was the minimum protection required.

 

[Jimmyb]

300mA was introduced with the 17th, prior to this 500mA was the minimum protection required.

does this include the house as well

 

[Deleted member 26818]

In my opinion yes.

 

[yellowvanman]

In my opinion yes.

Not so sure myself:

705.1 - "Rooms, locations and areas for household applications and similar are not covered by this section."

 

[spark 68]

Hi,
See page 46 in GN7, this shows the supply installation main DB (incoming supply), and this diagram explains all, basically 300mA rcd's feeding all submains related to agricultural (out) buildings, whether this main DB happens to be located in a residential building or not.

 

[yellowvanman]

Hi,
See page 46 in GN7, this shows the supply installation main DB (incoming supply), and this diagram explains all, basically 300mA rcd's feeding all submains related to agricultural (out) buildings, whether this main DB happens to be located in a residential building or not.

I agree, I was trying to point out that the house itself doesn't need the 300mA RCD.