mobile home park TT system

[stormy457]

Could you please help me with a couple of queries regarding regulations on a mobile home park?

Firstly, what are the site owners legal obligations with regard to additional protection in addition to each home owners RCD? Mobile home parks are fed from a TT system. In other words what protects the supply in the event of a mobile home either not being equipped with an RCD or having a defective RCD and then developing a fault? And if additional protection is required where would it be located?

Secondly, what are the site owners legal obligations with regard to testing electrical equipment for which they are responsible, i.e frequency, keeping records etc. Also what, if any, are their obligations with regard to ensuring each home has a working RCD?

Many thanks for your help
Stormy457

 

[Engineer54]

The RCD protection for mobile homes on a park patch, is via the supply to that patch. The socket outlet should be protected with a 30mA DP RCD ... Your not saying that the supply side socket outlet isn't RCD protected, ...are you??

Edit.... The supply to caravans doesn't Have to be TT it can be TN-S. It's only PME/TNC-S that isn't allowed to supply caravans...

 

[WDMDL]

I have a static on a park. They insist on a periodic at change of ownership, location or 3yr interval.
If you sublet they insist on appliances being PAT tested

Both the above by their sparks or a contractor you choose and they approve.
If done by your own contractor you have to supply the test documentation to the park for their records.
Mine's due next year so I wonder if they'll accept one from me?

All statics I've been in have an RCD incomer in the CU, but there's also an RCD and 32A MCB in the stump box outside.
The supply there is TN-S, not TT.

Simon.

 

[stormy457]

As far as I am aware there is no additional RCD or other protection other than that which would normally be in the mobile home at the consumer unit. In this particular case there is no RCD protection in the home either.

 

[Engineer54]

Then i'm afraid the Park owners have a rather large problem. All supplies to mobile caravans should be via an RCD/MCB protected socket outlet. The RCD is not classified as additional protection on a TT system, but the only means giving earth fault protection, and the means to meet protective device tripping times!!!

 

[stormy457]

Thankyou Engineer54
To clarify then
there should be an RCD on the meter, i.e when it then goes into the home, {park owners responsibility} then an RCD on the consumer unit {home owners responsibilty}? Have I got that right?

 

[Engineer54]

That's about it, as i see it anyway... Doesn't matter too much about an RCD being present in the caravan CU, there wouldn't be any discrimination between them anyway!!

 

[stormy457]

Thankyou very much Engineer54 and WDMDL, that was a lot of help, the home owner is the subject of a court case as a result of an electrical fault in her home which the park owners say caused faults on the supply and to other homes, and a fire on another home. They left her without RCD protection and she has never been asked for any certification to prove compliance. In short she didn't even know what an RCD was. Your info helps me to start looking at the regs to show up their shortcomings in applying their legal obligations. Many thanks.

 

[Engineer54]

I would say that if an RCD had been present at the park owners patch connection point, It would be doubtful if any problem could have been transferred to other caravans. I can't really see what fault in your friends caravan could have caused a fire in another anyway, but it's early here and not switched brain into gear yet ....lol!!

 

[stormy457]

Because you might find this interesting and because it would be interesting for me to hear your views, the voltage readings taken by Southern Electrical Contracting {SEC} at the time of the fault were
L-E 350 V
N-E 150 V
L-N 88 V
The readings were apparently taken at the meter box, 2 additional earth rods had been installed by the husband {he was trying to sort the fault out and is not qualified}. A part of the park had been experiencing problems for about a week, SEC say that the fault was eventually traced to this lady's home and when they disconnected her home all readings returned to normal.
As I said earlier she did not have an RCD and her wiring was in a poor state. It was the original wiring from when the home was manafactured in 1974. She is on a single phase {red} supply.
Your comments are welcome and Thankyou.

 

[WDMDL]

Someone's talking bull.
If those readings are correct, it points to a failed connection between the Neutral busbar of the main intake and the star point of the supply transformer.

Somehow, with averaging of loading between all caravans, the Neutral will have stayed NEAR zero Volts. But unbalance the loading between phases and this is what you would see. IE the problems being experienced for a week.

The fault COULD NOT have been IN the lady's home, but COULD have been in the stump box supplying it.

And yes, given 350V some electrical equipment has a VERY GOOD chance of chance of catching fire!


Simon.

 

[stormy457]

Thankyou Simon
We have been saying all along there must have been a broken or lost neutral, how can a single phase supply cause, on its own those readings? It can't.

 

[Des 56]

The supply could have a neutral problem,perhaps a local site may be on a different phase and the supply voltage could rise if the neutral was common to both






Nice pictures Ouch

 

[WDMDL]

Which incidentally is what had happened here on this fault I went to look at... cowboy joint of SWA into PILC cable.
This had been done on the outside of a building and just covered with a piece of orange neoprene sheet!
This had arced over and blew a fuse (300A) on one phase.
The fuse was replaced without proper testing. Two weeks later it arced over again and burnt through the Neutral. Now as the loadings were 85A, 20A and 25A, a rather large voltage imbalance occurred when the Neutral was lost.
It was Jan this year and only a couple of admin people were in... one rang the boss when the lights started pulsing and the computers were going BANG!




Oh and there was also no sheath or armour continuity either. Lovely!

Simon.

 

[stormy457]

The home in question is fed from the red phase of a 3 phase system with TT earthing and a common neutral. The transformer delivers power to 107 homes in total, 44 on red, 29 on yellow and 34 on blue.

 

[Engineer54]

I think your friend needs an expert witness on her defence!! This all sounds now very much like a supply problem rather than anything in her static caravan. In any case, the park owners are failing in there responsibility to provide adequate protection at the supply take-off points to caravan patches by not providing RCD protection. If there had of been a problem in your friends home and an RCD had been present, then if the RCD was working correctly it would have tripped out the supply!!

 

[WDMDL]

I take it the fault has been found and rectified now.... Are there any diagrams of how the supply is distributed?
Such as all single phase distribution from one point, or distributed 3ph with each pitch tapped off in sequence?

I'm certain there will be some tell-tale signs of where the fault was - evidence of arcing on terminals, a newly-made-off cable, or a conductor that now has heat-shrink sleeving over it etc.

Simon.

 

[Engineer54]

Any chance of some photos of the caravan patch owners supply point?? Opened if possible!! Might give some of us some clues...lol!!!

 

[Chr!s]

Sound more like an earth fault to me, which may be on your installation!

Regards chris