Caravan diversity question

[timhoward]

But for upper limits, B16 is 5X16=80A, vs C10 10X10 =100A. I can see selectivity with the upstream device being an issue if I use C10s?

Could you consider using fuses upstream?

 

[mainline]

These are supplied at the hookup unit.

18th Edition Caravan hook up 2 × 16A 2p+e switched interlocked outlet c/w 2 × 16A DP 30mA RCBO

www.yesss.co.uk

I'm fairly happy with the regs side of the job, I'm just trying to fathom whether I treat the circuit feeding the hookup unit as a 32A load, or if I can apply some diversity to it

Why do you need a double outlet ?
All the touring hook up sites i have seen have been single outlets with 30ma rcd and 16amp mcb.

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Also, all the Consumer units in the caravans / motorhomes i have seen has a 16 / 6amp MCBs and 30ma rcd.

 

[brianmoooore]

There's been regulation changes lately, and interlocked switched 16A sockets are now required with individual RCDs, which are usually RCBOs.
The usual set up is dual units, mounted on the dividing line between two pitches, or quadruple units mounted on the + between four pitches.
16A MCBs are OK, but 10A limits the possibility of customers taking the *iss with continuous heavy loads.

 

[Pretty Mouth]

Could you consider using fuses upstream?

Yes, I guess....

I'll be honest, I'm struggling with working out whether selectivity is guaranteed or not, whatever device I use. Looking into it further, it seems to be a very complicated subject involving comparing obscure manufacturer's data. There's not really any answers in BS7671, or the OSG, or any of the other books I own, that I have been able to find anyway. I watched a youtube on the subject, but I'm pretty sure that the guy trying to explain it is explaining it wrong. I did find some useful info in some of Hager's literature.

Trying to find this out feels like it's above and beyond the call of duty, and is making me look seriously at fast-track plumbing courses.

 

[Pretty Mouth]

Why do you need a double outlet ?
All the touring hook up sites i have seen have been single outlets with 30ma rcd and 16amp mcb.

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Also, all the Consumer units in the caravans / motorhomes i have seen has a 16 / 6amp MCBs and 30ma rcd.

As @brianmoooore said, it's 2 pitches, side by side

 

[mainline]

As @brianmoooore said, it's 2 pitches, side by side

Is there likely going to be other hook-ups in the future ?

Most caravans know not to draw too much, and a 2kw heater in a van will warm the van up in a minute or two.

 

[brianmoooore]

a 2kw heater in a van will warm the van up in a minute or two.

My son, who was banished to one over the winter of 2020-21, as a Covid precaution, would probably strongly disagree.
The 2kW heater in mine is only described as an auxiliary to the gas heater, which has an output of over 3kW.

 

[mainline]

Is there likely going to be other hook-ups in the future ?

Most caravans know not to draw too much, and a 2kw heater in a van will warm the van up in a minute or two.

Selectivity is always going to be a problem with having two 30ma rcds one at the hook up point and one in the van, even if using 100ma S type or similar at the source.

 

[Pretty Mouth]

Is there likely going to be other hook-ups in the future ?

Most caravans know not to draw too much, and a 2kw heater in a van will warm the van up in a minute or two.

The customer doesn't think there will be

 

[brianmoooore]

The customer doesn't think there will be

As we all know, the customer doesn't usually have a clue.

 

[mainline]

My son, who was banished to one over the winter of 2020-21, as a Covid precaution, would probably strongly disagree.
The 2kW heater in mine is only described as an auxiliary to the gas heater, which has an output of over 3kW.

You should close the windows then, or get a van that's insulated.

 

[Pretty Mouth]

Selectivity is always going to be a problem with having two 30ma rcds one at the hook up point and one in the van, even if using 100ma S type or similar at the source.

True, but what goes on in the caravan is out of our control. Regs say we have to provide RCD protection for the socket.

 

[brianmoooore]

Selectivity between the caravan RCD and the hook up point RCD isn't important. Selectivity between the hook up point nd the source of the power is.

 

[mainline]

True, but what goes on in the caravan is out of our control. Regs say we have to provide RCD protection for the socket.

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I would Time delayed rcd at source 10mm 2 core swa and rod at the Hook up.

 

[brianmoooore]

Can't have an S type for the 16A socket. There's no guarantee that the 'van has any kind of RCD, or it might be just a 13A extension lead to a tent plugged in.

 

[mainline]

Selectivity between the caravan RCD and the hook up point RCD isn't important. Selectivity between the hook up point nd the source of the power is.

Its still selectivity.

 

[mainline]

Can't have an S type for the 16A socket. There's no guarantee that the 'van has any kind of RCD, or it might be just a 13A extension lead to a tent plugged in.

I said at the source 30ma at the hookup.

 

[brianmoooore]

As Pretty Mouth says, we have no control over the van's installation, and the van owner has no control over what he plugs into.
Another potential problem that's beginning to appear, is that Motorhomes (often DIY made) often have petrol invertor generators built in, and who knows what the changeover arrangements are for them.

 

[brianmoooore]

Selectivity is always going to be a problem with having two 30ma rcds one at the hook up point and one in the van, even if using 100ma S type or similar at the source.

I said at the source 30ma at the hookup.

What's the point if the supply cable is SWA? No harm, but little point either, since there already should be two 30mA RCDs between the source and the customer.

 

[mainline]

Can't have an S type for the 16A socket. There's no guarantee that the 'van has any kind of RCD, or it might be just a 13A extension lead to a tent plugged in.

I said at the source 30ma at the hookup.

As Pretty Mouth says, we have no control over the van's installation, and the van owner has no control over what he plugs into.
Another potential problem that's beginning to appear, is that Motorhomes (often DIY made) often have petrol invertor generators built in, and who knows what the changeover arrangements are for them.

As you have just said, “no control over the vans installation”. So not a problem.