Static or not

[Engineer54]

Just as a point mobile homes semi permanent are required to have a PIR or in new parlance an electrical condition report when they are moved and reconnected they are also required to have an annual PIR if they are to be hired.All mobile homes we site are given a PIR after connection. It's amazing how many times RCDs fail testing, on a caravan site there are probably many many more RCDs than domestic guys come across.I wouldnt trust my life to an RCD. Just as an aside to BS7671 I have a system that runs 600v chopped DC at 20KHZ in water it is protected by a 9mA earth leakage detector and a continuous insulation test that trips if below 1.5Mohms. Would you go near it if protected by a commercial 30mA RCD

Fully agree with you there on the total reliance of an RCD device Mike!! Which is why i consider this BS 7671 200 ohm Ra level for a TT system, as a total farce.

 

[Strickers]

Cheers for all your comments not looking forward to talking to client tomorrow and explaining that all there supplies need changing to TT. Well bit of work for me.

 

[mike22861]

We try and get earth spike Ras below 10 ohms either by multiple spiking or other earth plate arrangements. BS 7671 doesn't give a calculated reason for the 200 ohm other than its likely to be unstable above this in my experience and Ra of 200 ohms is practically unacceptable it would certainly lead to a touch voltage over 50V which is what i thought the regs were all about keeping touch voltage below 50V