Supply to Touring Caravan Site.

[peterson]

What divesity would be applied to 5x16amp sockets for 5 touring caravans on a farm caravan site?

What size SWA would be required for a 300 metre feed from the farm supply to the site?

Your comments will be appreciated.

 

[The Godfather]

What divesity would be applied to 5x16amp sockets for 5 touring caravans on a farm caravan site?What size SWA would be required for a 300 metre feed from the farm supply to the site?

Your comments will be appreciated.

This is not my boys area, but I suspect this is going to be a large sized cable.

Have you done any calculations yourself?

Don

 

[SPECIAL LOCATION]

What divesity would be applied to 5x16amp sockets for 5 touring caravans on a farm caravan site?What size SWA would be required for a 300 metre feed from the farm supply to the site?

Your comments will be appreciated.

Welcome to the forum Peterson...

I must just say first of all.. This is a ruddy good opening question!!!

And I shall now have to say second of all... (as like wot the DON said).. I have absolutely NO personal experience of this area...

{other than actually towing a caravan & using camp sites :^O }

But putting my electrician head back on a can still bat a few thoughts out into the topic....

Considering the first Diversity bit:-

As far as I am aware, the regs or On Site Guide don't actually give any specific guidance re Caravans/Sites and diversity..

General guidance is given for typical final circuits in domestic & small commercial premises.. However it also states that Other methods of calculating Max demand are also permitted..

it talks about using any previous demand or historic records and any other relevant information.

Is this a brand new caravan site area.. or an upgrade/.rewire of an existing one?

i.e. does the owner have any past record of site utilisation.. e.g. how ofter is the site full?

Assuming there is absolutely no historic info.. we could make some basic assumptions...

1)

The average touring caravan has a max supply of 16A.

If all five pitches were in use simultaneously taking max load..

5x16 = 80Amps top end!

2)

Many modern caravans haves loads of 12v accessory's that can run off the battery..

and the battery is trickle charged off the mains hook-up.

things like built in ovens and plug in portable appliances probably take most off the 230v power consumption..

It may be quite reasonable to assume the individual caravan is taking 10A or less?

{our old caravan has a 10a MCB for all the sockets, a 6a for the lights & fridge!

our kettle is gas, we use an electric toaster 1700watt, the girls use hairdryer 2000watt,

most other stuff is low power, charges for phones, laptop etc.. }

3)

If we assume that either [a] the site is not always full. (3 or 4 vans not 5).

all the caravans on site aren't taking full wack at the same time...

Then realistic demand may be more around 40-50amps??

so top=80A, rough diversity=50A...

meet halfway... I guess 65A +/-?? maybe the answer?

It may well probably end up been at lot lower maybe just 40A?? ?:| ? :| ?:| ; )

I'll have a go at the other bit in a short while on my next post..

 

[SPECIAL LOCATION]

Just done a quick search...

found this little bit of info at the Voltimum website...

http://www.voltimum.co.uk/consult.php?action=main&mode=consult&father=&child=&textToSearch=&offset=&id=5348&universe=consult.index.questions

which says the following..

Subcategory - 1. BS7671 Can you offer any help on calculating maximum demand for caravan park? The park has 61 static caravans and 120 touring "hook ups" plus street lighting and two shower blocks. Also office and workshop.

----------------------------------------------------------

Can I ask you to refer to IEE Guidance Note 1, Appendix H.

However as stated in GN1, '....it is impossible to specify the appropriate allowances for diversity for every type of installation and such allowances call for special knowledge and experience.'.

Street lighting - 100% of the load must be considered as they are all likely to come on together.

Has the shower area electric water heating, are the lights on all the time?

How many static caravans are used at any one time? Similar with the touring hook ups? What is their maximum demand?

If this is an existing site, see if there is maximum demand metering, or try current monitoring.

Sorry if vague....

Although this questions refers to lighting & shower blocks...

the caravan bits.. appear to verify my gut instinct from previous post..

Try & get a bit more info off the caravan park owner...

and/or and other similar size parks within the local vicinity???

OR

maybe organisations such as the Caravan club / Camping & Caravan club etc... may have some tech help line who may be able to offer some advise as to typical realistic demand at their sites???

 

[NozSpark]

I did some work on a static site a year or so ago, they had a 400kVA transformer supplying 440 static vans (50A sub mains supplying 4 vans each - 10A supply to individual vans), about 12 touring pitches, shop, shower block, laundrette, offices, workshop & street lighting.. they had max demand metering and it never got up to 400kVA

BTW. showers h/w is heated by gas, tumble dryers (gas heated)

 

[SPECIAL LOCATION]

I did some work on a static site a year or so ago, they had a 400kVA transformer supplying 440 static vans (50A sub mains supplying 4 vans each - 10A supply to individual vans), about 12 touring pitches, shop, shower block, laundrette, offices, workshop & street lighting.. they had max demand metering and it never got up to 400kVABTW. showers h/w is heated by gas, tumble dryers (gas heated)

GOOD NEWS:-

Thats about what I guessed? 10A per van

BAD NEWS:-

I had just typed a whole bunch of calcs re cable size..

then pressed "Ctrl W" by accident....

closed me blo0dy Tab!!!!!X(X( X(

Lost all me typin!!!!!!!!! :_| :_| :_| :_| :_| :_|

I shall not be detered...

I shall start typing again!:| X(

 

[SPECIAL LOCATION]

What size SWA would be required for a 300 metre feed from the farm supply to the site?Your comments will be appreciated.

Right... lets assume 10A per van... max all vans 5 x 10A 50A

is the 300m the length to the furthest hook-up point?

or are all the hook-ups grouped together off the same supply cable?

You must ensure you do not exceed max volt drop..

previously used to be 4% (9.2v)

now re table 12A, Appendix 12, 3% lighting 5% other uses.

So assume 5% drop for caravan hook-up = 11.5volt

Using the volt drop formula we can work backward to get the max mV/A/m.

( (mV/A/m) x Ib x L / 1000 = 11.5

L=length

Ib = design current 10amp OR 50amp.

So...

1 Assume individual hook-ups wired

(mV/A/m) x 10 x 300 / 1000 = 11.5

(mV/A/m) x 3000 = 11.5 x 1000

(mV/A/m) x 3000 = 11500

(mV/A/m) = 11500/3000 = 3.83

volt drop must not exceed 3.83

so from table 4D4B pg 281 App4 smallest cable size is

16mm multicore armoured (2.8) needed to satisfy voltdrop...

Verify current & inst method with Table 4D4A.

2 Assume 5 hook-up together off one cable

(mV/A/m) x 50 x 300 / 1000 = 11.5

(mV/A/m) x 15000 = 11.5 x 1000

(mV/A/m) x 15000 = 11500

(mV/A/m) = 11500/15000 = 0.766

volt drop must not exceed 0.766

so from table 4D4B pg 281 App4 smallest cable size is

70mm multicore armoured 0.63 needed to satisfy voltdrop...

Verify current & inst method with Table 4D4A.

Remember cable will only need to be Two core because each hook up will be TT'd ref section 708, caravan parks...

Wait till someone else double checks my cals...

it is getting late now..

and its the second time I have typed them in!!!

Never trust anyone who wires a lighting circuit with a tub of water!!! :O:^O:^O:^O

 

[SPECIAL LOCATION]

It is now morning..

I have slept... and woken up...

and I have been thinking more about this...

A question crossed my mind with ref to the max permitted volt drop,

which you need to consider with your calcs...

reg 708.530.3 Pg 191. (paraphrase version)Caravan pitch supply equipment located not more than 20m from the connection point on leisure vehicle.

note: Not more that 4 should be grouped at one point!

reg 721.55.2.6. Pg. 213. (also paraphrase)Means of connection to the caravan pitch socket outlet shall be supplied via

BS-EN 60309-2 (blue commando plug/socket),

Flexible cord 25m (+/- 2m) C.S.A. 2.5mm for 16A

SO...

Is the volt drop just calculated to the pitch outlet

 

[a1]

I do believe that KME has experience in this area too? :|

 

[peterson]

Thanks for all the info to date. So quick and knowledgeable. Plenty of good ideas.

This is a new site and I agree that 10amps/unit should be ample.

The farm is PME. Do you say that I can use a 2core cable and go to TT at the remote end with earth rods, if so where is the SWA armouring bonded to?

I think that the 70mm cable might be the best bet (

 

[SPECIAL LOCATION]

Thanks for all the info to date. So quick and knowledgeable. Plenty of good ideas.

allegedly!!! ; \ :^O :^O

This is a new site and I agree that 10amps/unit should be ample.

The farm is PME. Do you say that I can use a 2core cable and go to TT at the remote end with earth rods, if so where is the SWA armouring bonded to?

I think that the 70mm cable might be the best bet (

 

[NozSpark]

Just a quick note to add - whilst the supplies to groups of vans was via C 50 MCB's each individual van had a connection point with a B 10 MCB and a 30mA RCD... these were connected up MCB - RCD, rather than the traditional RCD - MCB, as some of the RCD's and hence connection boxes were going on fire from time to time and the C50 MCB at the supply would not trip before major damage occurred.

 

[NozSpark]

The farm is PME.

Why has a farm got PME?????

TT the whole installation!!

 

[a1]

with a little nudging and persuasion we could get this topic round to our favourite "exported earth" discussions! ]

]

Lets wait & see if Admin was right and if KME can put a bit of input to verify or correct any points discussed so far?? ?:|

I do believe it was pre-17th Edition.

 

[kme]

Sorry for the delayed response guys - Sunday is my wine&nookie day ; ) .

I haven`t re-calc`d the calc Spec, as there doesn`t appear to be anything wrong - the figure for cable sizing are what I`d guesstimate if asked "on the hoof"!

Similarly, unless there is specific reason for having the 5 on seperate lines; I`d be looking at a 3/2 split - it SHOULD be slightly cheaper than 4/1 on materials:x

Mr. Peterson, I wouldn`t just plump for the 70mm - two reasons:

1. It`s way bigger than you actually need, since running all 5 from one line is not a recommended manoeuvre.

2. It`s a bit expensive, and, even at 2 core, a bit of a ***** to work with.

With regard to the farm/pme/tt business:

A farm on PME? I find that a little spooky TBH. Agree with Noz here, I`d TT the whole thing (outbuildings should be TT anyway - exported earths & all that).

Even if not, the pitches MUST be TT`d. One option is to terminate the SWA into a plastic box - no issues with continuity or exposed conductive parts.

As Our Admin alluded - We had a job a few years ago, TT`ing a caravan park. Luckily, I was employed at the time, and hadn`t priced the job.

We arrive first day, earth rod, meet lump hammer. Rod fairly flies into the ground - no Ra reading at all. OK - screw on a second rod - (don`t tap it - whack it).

Same result.

Turns out I had to put nine rods on in order to get a reading - The caravan park is on a flippin` sand dune!!!!!!!

We`ve got seventy odd pitches to do. We brought eighty five rods, and I used 9 of `em on the first pitch! and the second, and the third...........

Guess who had to try and explain who the price was SO FAR out from the estimate.

No, not me. I was knaffered from sending rods into sand all blinkin` week.

HTH

KME

 

[kme]

]

I do believe it was pre-17th Edition.

Ohh, Bless...... (you ARE naughty........)

 

[a1]

]

 

[SPECIAL LOCATION]

Sorry for the delayed response guys - Sunday is my wine&nookie day ; ) .

Too much information!!!

As Our Admin alluded - We had a job a few years ago' date=' TT`ing a caravan park. Luckily, I was employed at the time, and hadn`t priced the job.

We arrive first day, earth rod, meet lump hammer. Rod fairly flies into the ground - no Ra reading at all. OK - [b']screw on a second rod - (don`t tap it - whack it).

Same result.

Turns out I had to put nine rods on in order to get a reading - The caravan park is on a flippin` sand dune!!!!!!!

We`ve got seventy odd pitches to do. We brought eighty five rods, and I used 9 of `em on the first pitch! and the second, and the third...........

oh eck!!! :O

PMSL at the earth rods!!! :^O:^O:^O:^O:^O

me thinks a good lesson..

Do a sample test inserting one earth rod test before quoting for several pitches!!! :|

 

[kme]

Too much information!!!oh eck!!! :O

PMSL at the earth rods!!! :^O:^O:^O:^O:^O As was I mate. :^O

me thinks a good lesson..

Do a sample test inserting one earth rod test before quoting for several pitches!!! :|

That was a lesson I very quickly worked out bud - Very expensive mistake:_|