Park Homes

rll13 · Feb 22, 2009

Hi,

I would like an opinion regarding Park Homes/ Static caravans. At present each dwelling is fed via buried 2.5mm 3 core SWA with 20amp C mcb from a local distribution centre. The armour and one core are connected together to provide a combined earth.

My question is that measured Ze at the Park home connection is around 7 ohms. The home has a 30ma RCD as an incomer. As this is a TN system and not TT would anyone adivise an additional earth stake to try and lower the Ze or will this introduce additional problems.

If this were a TT system the readings comply with regs. The RCD trips at rated values.

Many thanks

RL

Spudnik · Feb 22, 2009

Hi RL.

There is a section in the regs that covers this type of install.

However, i think you could either leave the existing earthing alone and TT at the supply end, or you could TT each pitch.

rll13 · Feb 22, 2009

Hi Jason

Thanks for the input. These homes/caravans are not the touring type and I think are considered to be houses in there own right. I can't find any definitive section in the regs regarding them. Regarding the Ze from the combined core/armour (TN) and considering it is lower than a stake and the input to the caravan is an RCD, would you consider this to be sufficient to satisfy regs.

RL

Spudnik · Feb 22, 2009

This value is probably lower than a stake, however, it is too high for a TNS system (0.8).

Therefore, i would definatley stake each 'pitch'.

Guest123 · Feb 22, 2009

Hey there.

Pesonally I would look at converting each pitch into TT installation and treating it almost as a caravan type pitch.

The distribution points would be on a TN-S system providing the Ze readings at these points are within limits, with all supplies to statics then being TT.

As J said your values of Ze for a TN system are way off and so don't comply.

Hope this helps