Club 80-90 Forums

I'm trying to get my head around what's required for 240v hook up and consumer units and was wondering if any sparky wizards can help...

I understand that current regulations stipulate that double pole mcbs when it comes to camper vans - or 1P+N breakers are acceptable and meet regulations (this makes for scintillating reading from the T4 forum: http://bit.ly/183OHzj" onclick="window.open(this.href);return false;). It seems quite a few conversion companies ignore this and just stick with regular single pole breakers.

So... am I right in thinking I could use a standard small consumer unit (like this one http://bit.ly/15aUYqO" onclick="window.open(this.href);return false;), and replace the mcbs with a 6A and 10A 1P+N breakers like these: http://www.parkelect.co.uk/rockwell-1p-mcb" onclick="window.open(this.href);return false;). Thus meeting regulations?

As long as you have a 30mA rcd up front you will be fine. A common double pole mcb would be an rcbo which is an mcb and rcd combined. Problem is they are slightly taller so a bit of a squeeze. Current regs state you cannot mix a match brands so you would still not comply.

http://www.parkelect.co.uk/10a-type-b-r ... antId=1444" onclick="window.open(this.href);return false;

Just get a garage consumer unit as that is all you will probably need.

MCBs - circuit breakers, what used to be called "fuses" - are just single-pole. They only cut the live, when their current rating is exceeded, same as the fuse in a plug.
RCDs are what cut both live and neutral when there's a short to earth - and, in a camper, anything metal is earth - preventing it all getting sparky-tingly.

That £21 Volex CU does have a double-pole (DP - says so in it) RCD, so should be just fine.

People fit double pole in some cases as supplies in europe are often reverse polarity so if you only have single pole you must use a polarity checker before plugging in and a converter lead if it's switched.

Thanks for the relies chaps - as you say 123-jn, the problem seems to be with Europe and the possibility of reverse polarity.

I didn't realise you couldn't mix brands billybigspud, it gets more complicated!

uniB wrote:Thanks for the relies chaps - as you say 123-jn, the problem seems to be with Europe and the possibility of reverse polarity.

Ah, I see the issue now!

AdrianC wrote:

uniB wrote:Thanks for the relies chaps - as you say 123-jn, the problem seems to be with Europe and the possibility of reverse polarity.

I wish people would refrain from giving advise where they do not know correctly what they are talking about.

The current regs state that "all final circuit over current protection devices shall be double pole" this means the circuit breaker, MCB or trip switch call it what you will must be double pole.

Please bear in mind that most of the regulations with regard to the "special location" of "mobile or portable installations" are designed to protect you the user from the effects of reverse polarity in a fault situation.

With a double pole circuit breaker in the event that it trips (when you forget to unplug the fan heater while you put the kettle on) for what ever reason there are no live parts of the circuit whilst the breaker is in the tripped position.

With a single pole breaker, when tripped the neutral conductor is still connected, in a reverse polarity situation, the breaker would interrupt the neutral conductor, thus leaving the live conductor of the now reversed circuit energised.

That's why you shouldn't rely on the RCD main switch.


Some other points to note

The RCD main switch is a switch, it has a current carrying capacity, but not an overcurrent rating, ie if it says 100A on it, that is its safe operating limit, it will continue to carry current untill it catches fire rather than to interrupt the supply as a result of overcurrent.

The RCD compares current in on the live with current out on the neutral any variance of above 30mA and it will activate and interrupt the supply.

An rcbo is a combination of an RCD and an overcurrent protective device, it will do both.

A double pole circuit breaker is purely an overcurrent device.

All installations in a camper or other mobile vehicle should be carried out using flexible cable. - don't forget a 4mm Earth to the chassis also.



That is what the regs say, however most DIY installers and quite a few professional installers will disregard this I favour of a £30 garage consumer unit under the misguided belief that the RCD is the all saving creature.

If we want to go strictly by the book, you should have your installation tested and inspected every 1-3 years dependant on use and detrimental influence.


Also because I' m off on one, the regs do not prohibit the mix and match of brands for boards and breakers, the regs had the all covering "all accesories must be installed in accordance with manufactures instructions" which as you'd guess will most likely state that only breakers of the correct/same brand may be used.

This has been replaced in the latest amendment with " all accessories must be installed taking consideration of the manufactures instruction"



Sorry