Caravan/static Office Help!

[muskrat]

Hi all this is my first post so please bare with me!

the other night i was called out to a job where a shower was tripping the main rcd, the phone call was sketchy but went out anyway. it turns out that an other electrician had set up an 8 plot caravan site. each plot has its own 16amp rcd and meter.  the couple in question have decided to buy an old porta cabin and put it on site instead of a caravan. it has in it a main fuse board with light ciruits heaters water etc and a shower. someone had connected this board to the 16amp board outside and hey presto when they turn the 40amp shower on it trips the 16amp rcd outside!

so i know caravan parks are limited to providng a 16amp pitch and on some sites lower at 10, i have checked section 708 and 721 in the regs book but not really found an answer, can i legally change the 16amp rcd for say a 40amp rcd and install a suitable swa cable from the meter to the porta cabin so they can run a shower?

the site is a private one all the residents are permanent, the other 7 are in caravans but i think they all intend to buy some sort of static home in the near future. so will all face the same problem but this is a new one on me!

i hope you understand the question and someone can help.

many thanks dan

 

[Technician]

hey presto when they turn the 40amp shower on it trips the 16amp rcd outside!

Before anyone else comes in, the RCD is not a circuit protective device.

If this is happening there must be a line to earth fault causing it to operate.

If it was an RCBO then, under an overload, it would operate.

 

[ProDave]

Well you can't just go changing the 16A MCB for a 40A one, because that will overload something else somewhere.

So there are 2 choices:

Replace the shower with a gas powered one (like probably fitted to the other caravans) or one that operates from a stored hot water tank that can be heated slowly with a low power heater.

Or talk to the site owner and see if he's willing to spend the money to upgrade the power available to each pitch, but that almost certainly won't be a trivial exercise.

 

[thewiz]

RCD will not trip on overload the MCB will 

You will need to find the fault that is causing the RCD to trip. If you upgraded the RCD to a 40A then you will need to up grade the cable witch feeds the 16A RCD. the cable fitted at present will most likely to be 2.5-6mm depending on distance ect. I dont think he will want you to dip up his land for a shower. 

 

[muskrat]

ok thanks, ive maybe used the wrong terminology!  it is a 2 pole rcd 16amp 10ma,  i have obviously jumped to the wrong conclusion then! 

 

[muskrat]

i did suggest calling a plumber! i spoke to a plumber i work with and he said head room would be an issue! they did take me to see a distribution board for the site, everything there was through 32amp mcbs 1 to each site and then some 20's running the site lights dotted about! they said there was another board feeding that but i never saw that one! 

 

[Andy™]

ok thanks, ive maybe used the wrong terminology!  it is a 2 pole rcd 16amp 10ma,  i have obviously jumped to the wrong conclusion then! 

as above, an RCD will not trip on overcurrent. an RCBO will though

only options are above, either remove the shower or upgrade the supply

 

[ProDave]

You need to be clear if you are talking about an RCD, MCB, or RCBO. If you don't know the difference, perhaps that plumber might know :coat

If it really is a 2 pole 16A / 10mA RCBO then of course it will trip if you try and run a 40A shower.

 

[thewiz]

Yes the RCBO will Trip but not the RCD. as you said he needs to be more clear. 

 

[Steve3948]

I think its 100mA also and not 10mA thats mighty sensitive and you don't see many.

 

[Andy™]

iirc, an RCD on caravan site must be 30mA max, so 100mA wouldnt comply

 

[Sidewinder]

It "could" be a 10mA RCD, or RCBO, they are rare & expensive, but they are available.

 

[Steve3948]

It "could" be a 10mA RCD, or RCBO, they are rare & expensive, but they are available.

Sidewinder/Andy - That's my point 30mA it should be, but from post it says 10mA which seems unlikely, but probably 100mA.

Last time i came across 10mA was on MOD job in a lab, 30 years ago, not seen one since.

 

[binky]

RCD may be tripping due to melted cable...LOL Think he's just terminolgy wrong,or no-one has fitted MCB, so how about answering the upgrade question, basics of, like can a porta cabin have more than 16A RCD protected supply

 

[Andy™]

like can a porta cabin have more than 16A RCD protected supply

of course, thats why it doesnt say it cant have in the regs

you could wire it with a 125a connector if you wanted to. or something larger

 

[binky]

portacabin sort of posh shed would count as permanent building? Ergo OP is getting confused by caravan site status??

to easy to give grief to op, just tryimg to deflect conversation to something more constructive, like mixing permanent structure with caravans

 

[muskrat]

thanks 

binky
got bogged down giving you all some back ground info lol but that is the jist of it.   it has been set up as a caravan site and this family have stuck a porta cabin on it expecting to run a mains shower and other normal stuff.   that was my initial suggestion to them was to upgrade the cable, but was not sure about the regs!! but now understandabley a porta cabin is not a caravan! thanks for all input

 

[binky]

I should read palms for a living...... :^O

 

[ProDave]

thanks 

binky
got bogged down giving you all some back ground info lol but that is the jist of it.   it has been set up as a caravan site and this family have stuck a porta cabin on it expecting to run a mains shower and other normal stuff.   that was my initial suggestion to them was to upgrade the cable, but was not sure about the regs!! but now understandabley a porta cabin is not a caravan! thanks for all input

It's got nothing to do with a portacabin not being a caravan. You seem to not understand that you can't just increase the size of a circuit breaker without changing anything else..  Which part of that do you not understand.  It scares me you are practising as an electrician if you don't understand that.

 

[binky]

calm down Dave, he's just got himself confused with some terminology