Static caravan

[c.boy]

Hi all,
Got a look at a job today in a traveling site, we are installing a supply to a static caravan! The supply is tncs to a metal clad d/b in an out house,all circuits have rcbo protection!! There is a 100a rcd fitted,fed from the main isolator switch then feeding the d/b!! My ? is obviously the ze was very poor and this was put in at some point to overcome that, however with all circuits now protected by rcbos is the rcd still required?? Tight for space to install 4x4 box for the s.w.a supplying the van post.And forgive me if I'm being thick but how does fitting and rcd solve the high ze??

An an earth rod will be installed for the caravan supply tho!!

 

[telectrix]

because a TT system will have a Ze value too high to trip a fuse/breaker in the event of a fault, a RCD will perform this function with a Zs of up to 1667 ohms for a 30mA device.

 

[c.boy]

So with all the circuits being protected by the rcbos. There's no need for the rcd?

 

[telectrix]

what does the existing RCD protect? is it there to protect the feeder cable to the DB?

 

[Guest77]

Hi all,
Got a look at a job today in a traveling site, we are installing a supply to a static caravan! The supply is tncs to a metal clad d/b in an out house,all circuits have rcbo protection!! There is a 100a rcd fitted,fed from the main isolator switch then feeding the d/b!! My ? is obviously the ze was very poor and this was put in at some point to overcome that, however with all circuits now protected by rcbos is the rcd still required?? Tight for space to install 4x4 box for the s.w.a supplying the van post.And forgive me if I'm being thick but how does fitting and rcd solve the high ze??

An an earth rod will be installed for the caravan supply tho!!

The caravan supply needs to be a 30 ma double pole RCD as you have converted the supply to a TT system.

 

[c.boy]

Yes it splits the tails coming from the isolator to the main switch on the consumer unit!

 

[c.boy]

The caravan supply needs to be a 30 ma double pole RCD as you have converted the supply to a TT system.

The supply hasn't been changed yet that's my ? The 100a rcd is splitting the tails from the isolator then to the 100a main switch on a consumer unit with all circuits on an rcbo.

 

[Guest77]

The supply hasn't been changed yet that's my ? The 100a rcd is splitting the tails from the isolator then to the 100a main switch on a consumer unit with all circuits on an rcbo.

But you said you were changing it ?

 

[c.boy]

But you said you were changing it ?

I was hoping to keep the outhouse on the tncs supply, and the caravan on the tt! Clearly marked and labelled!

 

[c.boy]

Had another look today was late last night and head was fried!! I think you must have miss read my original post tho!! I've kept the out house on the tncs supply and the caravan on tt!!! I said the caravan was being put on tt not the out house!! Which had the 100a rcd feeding the rcbo fuse board!! Was a strange setup should have posted a pic thanks tho.