240, mains wiring on a 12 volt system/supply?????

[old-mo]

Just read another thread =

Wrong wiring?

Hi all. First post here. I’m building an Iveco van conversion and about 70% completed. I’ve just realised that I’ve used the wrong wire for a couple of items and wanted some advice. Basically I used 30amp rated wiring for a couple of things that would be fine with wire half of that thickness...

www.motorhomefun.co.uk

Just wandering why not use 240 wire..???

Not anticipating doing any wiring now or in the future, just curious why you should not use mains wire..

To my little knowledgeable brain I would have thought it would be safe..... being far heavier than 12 volt wire..

As said... Just curious....

 

[Sandancers]

Just read another thread =

Wrong wiring?

Hi all. First post here. I’m building an Iveco van conversion and about 70% completed. I’ve just realised that I’ve used the wrong wire for a couple of items and wanted some advice. Basically I used 30amp rated wiring for a couple of things that would be fine with wire half of that thickness...

www.motorhomefun.co.uk

Just wandering why not use 240 wire..???

Not anticipating doing any wiring now or in the future, just curious why you should not use mains wire..

To my little knowledgeable brain I would have thought it would be safe..... being far heavier than 12 volt wire..

As said... Just curious....

If by "mains wire" you mean twin and earth, then it's NOT a flexible wire. It's meant to put into you wall or whatever and not be wiggled or shaken or thrown about. What is needed in MHs is multi-strand wire. This is able to withstand shaking etc. Obviously the more strands in the wire then the greater the current it can carry.

 

[Bognor Saint]

We had a Conway folding camper. Previous owner had wired it with twin and earth which the dealer removed and replaced with flexible 3 core cable.

 

[chaser]

If by "mains wire" you mean twin and earth, then it's NOT a flexible wire. It's meant to put into you wall or whatever and not be wiggled or shaken or thrown about. What is needed in MHs is multi-strand wire. This is able to withstand shaking etc. Obviously the more strands in the wire then the greater the current it can carry.

but presumably the wire is going to be fixed in a motorhome and not moved.

 

[tonyidle]

To my little knowledgeable brain I would have thought it would be safe..... being far heavier than 12 volt wire..

Mains cable and flex uses better insulation than 12v wire adding unnecessary weight and bulk. The copper inside needs to be much thicker for 12v for any given load in Watts. For example 50W at 250v will cause the supply cable to carry 50/250 = 0.2 Amps but 50W at 12v is 50/12 = 4.2A

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[tonyidle]

but presumably the wire is going to be fixed in a motorhome and not moved.

Motorhome converters without exception use flexible cable for mains wiring because the mounting surfaces are subject to vibration in a moving vehicle. For the same reason all vehicle low voltage wiring in any type of vehicle uses flexible, stranded, wire.

 

[thebriars]

Looking back at the quote in the OP there is a basic mistake there for starters, never mind the need for multi-strand cable. He quotes the cable as being 30amp. Standard mains cable wiring for sockets is 2.5mm. That has a rating of 20-23 amps, not 30 amps depending on where it is. While consumer unit circuit breakers are 30 amps, there is always a ring main, so the electricity can flow either or both ways from the consumer unit to the sockets, thus doubling capacity.

To get 30amps from a single cable you would need to use either 4mm or 6mm cable, and anyone who has handled either of these will know it is hefty stuff.

 

[Lenny HB]

The only difference with mains flex and low voltage flex is the insulation standard, I use whatever I have around.

 

[Lenny HB]

Looking back at the quote in the OP there is a basic mistake there for starters, never mind the need for multi-strand cable. He quotes the cable as being 30amp. Standard mains cable wiring for sockets is 2.5mm. That has a rating of 20-23 amps, not 30 amps depending on where it is. While consumer unit circuit breakers are 30 amps, there is always a ring main, so the electricity can flow either or both ways from the consumer unit to the sockets, thus doubling capacity.

To get 30amps from a single cable you would need to use either 4mm or 6mm cable, and anyone who has handled either of these will know it is hefty stuff.

Just looked at the other thread he doesn't make it clear but it does look like he has used solid (T&E) so I would change it for flex to avoid future problems from vibration.

 

[Richard n Ann]

It would have to be a hell of a vibration to break a twin and earth cable wouldn't it. I think my fillings would come out first.

Still, it's theoretically possible I suppose ?

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[Lenny HB]

It would have to be a hell of a vibration to break a twin and earth cable wouldn't it. I think my fillings would come out first.

Still, it's theoretically possible I suppose ?

More likely to vibrate out of connectors that aren't designed for it.

 

[maxi77]

but presumably the wire is going to be fixed in a motorhome and not moved.

But what it is fixed to will vibrate, ie move and that is what will do the damage. Suitable flexible cabling is required what ever the voltage.

 

[Camping Gaza]

apart from flexibility, cable mm2 15amps at 240v AC in a ring main is different to 15amps at 12v DC in a non ring main circuit. Its a lot smaller, because of the "higher pressure of voltage" at 240v

Its also not practical as most mains wire is twin and earth in the same sheath and has the same 3 colour code, not good when trying to connect different circuits. Imaging fault finding, and the wiring diagram....!!

 

[pappajohn]

It would have to be a hell of a vibration to break a twin and earth cable wouldn't it. I think my fillings would come out first.

Still, it's theoretically possible I suppose ?

Solid copper wire 'work hardens' with vibration or constant bending and effectively becomes brittle, that's why it breaks.

 

[chaser]

when we wired ours up we used orange artic hookup cable for both sides , is that bad, must say there isnt a lot of it

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[thebriars]

Technically yellow arctic cable signifies 110v, blue arctic is for 240v, hence why the EHU connectors are blue.

 

[maxi77]

Technically yellow arctic cable signifies 110v, blue arctic is for 240v, hence why the EHU connectors are blue.

Most retail ones are orange

 

[chaser]

Most retail ones are orange

yeah i did say orange, but is it ok on the volt side

 

[tonyidle]

The only difference with mains flex and low voltage flex is the insulation standard, I use whatever I have around.

So do the people who built my Le Voyageur. A lot of the 12v wiring is in 3 core mains flex with the yellow/green chopped back to the sheath - except where, in a couple of cases they needed 3 wires. Like you I use mains blue and brown for +12 and 0v respectively - my last Hymer used those colours - but I draw the line at twin & earth flex still in an outer sheath for 12v. Apart from anything else it takes up a lot of room in trunking or conduit.

 

[thebriars]

Most retail ones are orange

Orange cable is not arctic cable.

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[Lenny HB]

Most retail ones are orange

You can get in orange but it is not very common I don't know of any retailers that stock it. As thebriars says Arctic cable is nearly always Yellow or Blue.