Caravan bonding

[Adrian Sadler]

Hiya

Anyone know whats the minimum size for cable is for...

A. Cu to rod
B. Gas/water/chassis bonding

also if metal framework of the door need extratous bonding?

Cheers

 

[Adrian Sadler]

Kinda helps a little. Still none the wiser why a rod is used from that though. Or even if its meant to be.

See...... I understand if this was plugged into a 13a socket. Its the genny thing thats thrown me. Also every mortal thing is bonded together back to the cu. Including the frame of the genny. My original queation was what sizes should the bonds be but its run deeper now. I love my friday night questions lol

 

[davesparks]

There's no point having a bond any bigger than the cpc in the supply cable used to connect it to the mains supply.

 

[Adrian Sadler]

So 2.5mm bonds to chassis water and gas are fine

One reason why it may be rodded is that on some sites 240v is present but still usedboff a genny. If the chassis was to become live with a supply from anbexternal source then the van would be live and no protection would blow for anything? Untill someone touches the door to open it and zap....

 

[davesparks]

So 2.5mm bonds to chassis water and gas are fine

One reason why it may be rodded is that on some sites 240v is present but still usedboff a genny. If the chassis was to become live with a supply from anbexternal source then the van would be live and no protection would blow for anything? Untill someone touches the door to open it and zap....

The rod won't help in that situation at all, and I can't quite get my head around what fault would cause that situation in the first place

 

[Adrian Sadler]

My first thank you lol

I hope thats right though....

 

[Leesparkykent]

So 2.5mm bonds to chassis water and gas are fine

One reason why it may be rodded is that on some sites 240v is present but still usedboff a genny. If the chassis was to become live with a supply from anbexternal source then the van would be live and no protection would blow for anything? Untill someone touches the door to open it and zap....

If mechanically protected, minimum of 4mm if not.

 

[Adrian Sadler]

Imagine a building site on the side of a school. Van fed by genny and van totally isolated from ground. A lead is run from the office supply. Lead gets snagged on the van and makes the van live. No fuse would blow? Unless a rcd in the offices.

So a live van will be fine till joe bloggs standing on the floor outside touches the metalwork and get fried. If the chassis was rodded to earth then 'faulty' lead protection would blow as it would complete the circuit. Bit far fetched i know.....

 

[davesparks]

If mechanically protected, minimum of 4mm if not.

Why? The incoming earth conductor will be 2.5 on the mains supply and the generator will be incapable of delivering any kind of fault current

 

[davesparks]

Imagine a building site on the side of a school. Van fed by genny and van totally isolated from ground. A lead is run from the office supply. Lead gets snagged on the van and makes the van live. No fuse would blow? Unless a rcd in the offices.

So a live van will be fine till joe bloggs standing on the floor outside touches the metalwork and get fried. If the chassis was rodded to earth then 'faulty' lead protection would blow as it would complete the circuit. Bit far fetched i know.....

You could say the same about any metal object in the area. That lead could just as easily get snagged on a wheelbarrow and cause the same problem.

Unless you can gaurantee the rod will have a very low Ra it won't be much use at causing an OCPD to operate.

 

[Adrian Sadler]

So not needed but belt n braces really

 

[Adrian Sadler]

Question is - if its electrical seperation. And a rod is used - why is there 240 l-e?

 

[Leesparkykent]

Why? The incoming earth conductor will be 2.5 on the mains supply and the generator will be incapable of delivering any kind of fault current

543.1.1 which also references 543.3.1

543.1.1 is to long to type out lol

 

[UKMeterman]

I don't have a copy of the wireing regs to hand, but in the special locations they now have sections for outside broacast vehicles and similar. You could use the same rules here, if the generator is TN-S then all the earth rod is doing is stopping people getting any shocks off any stray earth leakage, in some cases a dining fork has had a low enough impedance to deal with the stray micro amps...

 

[Adrian Sadler]

Tns genny same as floating earth genny?

 

[Dave OCD]

Nothing would happen if it's not referenced to earth, that's the whole point of electrical separation

The granny won't be standing in mud, it's mounted on the van, unless I've read the OP incorrectly

Who's granny?, and more worryingly why's she mounted on the van ??? :uhoh2: