testing static caravan installations

[Kiers1970]

HI Lads,


Had an enquiry about testing Static caravans on a caravan park (state the obvious!)
Anything in particular I should be aware of?

 

[telectrix]

are you testing the caravan electrics or the supply to them?

 

[malcolmsanford]

Obviously a good read of section 708 for the site and if your doing anywork inside the units section 721 of the book.

Like all testing the further you delve into it the more you will find. I suppose it is really down to age and condition. I've not done that many, and I'm sure some of the others will give you better advice but I found

1 Earthing was always hit and miss so look at that
2 Environment because everything is outside things tend deteriorate
3. Because of the nature of the beast, ie users, things tend to get damaged
4. Length of runs for cables. I don't think I ever did one that never had a vold drop issue or a Zs issue
5. Cost. The site owners are reluctant to spend and so make sure you cover yourself with terms and conditions
6. RCD protection or lack of it
7. RCD operation. Can bet a pension if there is RCD protection they have never been tested on the trip button since the last PIR

I'm sure there is more if I sat and thought more, but I won't be greedy lol

 

[telectrix]

i have come across several that have a 100mA RCD front end of the caravan CU.

 

[dingledong]

i'm doing work in a caravan now and on the park rcd's next to the meter outside nice when its pouring down and it trips

 

[telectrix]

that's why snooker cues were invented.

 

[steve-the-hat]

Having done some of these, I would echo everything that Malcolm has said, especially point 5.

Earthing can be very interesting. Especially with a combination of corrosion, water ingress and no RCDs anywhere.

If you are just testing the van itself, rather than the site, then I would suggest temporarily hooking the thing up to a suitcase genny. That way you can eliminate all the site's "features" from the test.

I can also assure you that testing the local RCD will trip one hidden in a shed on the other side of a very muddy field. Discrimination? What's that then...

 

[Kiers1970]

thanks for the replies!

Its apparently just the 'vans, doubtless, there will be issues with the supply's from the 'landlords' too.

 

[richy3333]

As Malcolm has highlighted, plus discrimination of RCD's, use of TNCS earthing, chassis bonding (corrosion issues) etc

 

[dingledong]

discriminatrion is when you dont want more immigrants coming over

 

[WDMDL]

721 doesn't apply to statics... you treat them as a normal domestic installation. (721.1, note 1) even though they may be connected to a stump box via a bit of 4mmsq arctic cable and a 32A commando plug.

Discrimination? No.
The site mine is on has a B32 and 30mA RCD in each stump box.Most caravans seem to have a small garage type board with 40A 30mA RCD main switch, a 6A lighting radial and 32A ring.
Some bigger vans may have 2 lighting circuits.
The stump box RCD trips first usually!


Mine's been modified though, the park sparks had fitted fused spurs off the ring in each room for electric panel heaters for the previous owner, but I put them on their own 16A radial and added a couple more so I could use a heating programmer and contactor.
I've also got a 16A radial for the electric oven.
I've got a bit of fancy overload prevention though, so the panel heaters are cut off (NC contactor) when the oven draws over 2A.

Edit:
I was quite surprised - the Ze is 0.30 Ohms and PSCC 2.4kA. My caravan is some distance from the intake building.

Simon.

 

[i=p/u]

i though each one had tt earth, nearly certain thats the way ares was ... few years ago mind you

 

[MarkieSparkie]

Discrimination? What's that then...

According to the Sepp Blater Book of Elektrikery. If there's a 'black-out', 'brown-out' or 'trip', in the field, it's solved with a hand shake.

 

[WDMDL]

i though each one had tt earth, nearly certain thats the way ares was ... few years ago mind you

The supply is obviously TN-S to my pitch, but quite possibly the touring pitches have a TT arrangement with local rod.

I do know some of the more remote pitches have a Ze higher than the 0.8 Ohms generally taken as a maximum for TN-S. I've not encountered one over 1.5 Ohms though.

Simon.

 

[richy3333]

i though each one had tt earth, nearly certain thats the way ares was ... few years ago mind you

708.411.4 TNS or TT. TNCS prohibited by BRB and ESQCR. Statics are non permanent buildings and are normally found to have their wheels still fitted even though they might be up on brick pillars, or the like. The owners often put a small wooden 'pelmet' around them to hide this.