Mains hook-up dangers

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cassandra
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Mains hook-up dangers

Post by cassandra »

A word of caution to any one with a T25 that is still very original. We have just bought a 1981 Eurec Cassandra ( which is actually a Devon Moonraker but converted in Holland ) and whilst modifying the mains system to allow for a different fridge, I discovered that there was no real protection for the mains system, no earth leakage trip (RCD), no circuit breakers (MCBs) and no earth bond to the van body!
I know some of us like to keep our vans as original as possible but sometimes we need to embrace modern safety requirements to avoid grabbing the door handle of a van which is live due to a faulty appliance and ending up hospitalised or worse so please check your mains installation and at the very least run an earth wire from the incoming mains to the body of the van if there isn't one fitted.
It is actually a requirement that any vehicle plugged in to a mains system on a campsite in the UK has an RCD and the site owner should refuse to let you plug in if you cannot show that one is fitted. although I have never even been asked.
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Re: Mains hook-up dangers

Post by Winchweight »

I don't know if it's a requirement in law, but common sense says it's absolutely is a requirement in your van. We have an inline one on our hook up cable and the van also has one. Everything is earthed as the risk of shock is huge.
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Re: Mains hook-up dangers

Post by max and caddy »

This has been a concern to me in on occasion....not sure a van can be earthed as such..not without driving a stake into the ground and running a cable to it from the body...I'm all ears on the topic...but I'm inclined to think if the earth wire in the hook up cable became detached , and the live got into contact with the van body ( unlikely but possible considering the vunerablilt you the socket etc) then when stepping out of the van or touching an awning pole for example then YOU would become the earth path...

I'm no expert on the subject...I prefer 12v...but in sure 4 rubber tyres won't provide an earth path?

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Re: Mains hook-up dangers

Post by Smcknighty »

I was about say tyres are meant to insulate you from lightning - turns out that's a myth http://science.howstuffworks.com/nature ... tning8.htm" onclick="window.open(this.href);return false;

Dunno..


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Smcknighty
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Re: Mains hook-up dangers

Post by Smcknighty »

http://www.practicalcaravan.com/forum/t ... of-a-shock" onclick="window.open(this.href);return false;

I particularly like this reply - not sure if it's true Whatever you do DO NOT connect your caravan chassis to ground. The nearest earthing point of the supply system may be at a substation some distance away which could mean that you earth is better than that of the supply company and considerable current could flow albeit from a very low voltage.

Thinking about it more, the only 'safe' option is an RCD near source isnt it?


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Re: Mains hook-up dangers

Post by Oldiebut goodie »

If you think about what tyres are made of you will soon realize that they aren't a good insulator. (carbon black)
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Re: Mains hook-up dangers

Post by DiscoDave »

Smcknighty wrote:http://www.practicalcaravan.com/forum/t ... of-a-shock

I particularly like this reply - not sure if it's true Whatever you do DO NOT connect your cara van chassis to ground. The nearest earthing point of the supply system may be at a substation some distance away which could mean that you earth is better than that of the supply company and considerable current could flow albeit from a very low voltage.

Thinking about it more, the only 'safe' option is an RCD near source isnt it?


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so you don't earth the exposed metalwork of the van - there is a fault within your van where a live wire touches the body work - regardless of weather or not the the earth to the van in the hook up cable is present if the body work is not connected to earth you will be the earth path. similarly the RCD won't work until you make the earth path, meaning you will receive at best a shock. This is the reason why you connect the body of the van to the earth terminal in the consumer unit.

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Re: Mains hook-up dangers

Post by max and caddy »

Oldiebut goodie wrote:If you think about what tyres are made of you will soon realize that they aren't a good insulator. (carbon black)

Rubber is a fairly good electrical insulator I reckon....they used rubber insulated cables for a good many years, and my tyres are not made of carbon although it may be an ingredient, furthermore there may not even be an electrical path to the wheel itself due to bushes and mounts...if you think about it...potentially the bushes and mounts could be polyurethane..if you think about it...more.

Ever received a static shock of a car door...not sure who is live and who is earth in that scenario.
Last edited by max and caddy on 21 Sep 2016, 19:11, edited 1 time in total.

max and caddy
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Re: Mains hook-up dangers

Post by max and caddy »

DiscoDave wrote:
Smcknighty wrote:http://www.practicalcaravan.com/forum/t ... of-a-shock

I particularly like this reply - not sure if it's true Whatever you do DO NOT connect your cara van chassis to ground. The nearest earthing point of the supply system may be at a substation some distance away which could mean that you earth is better than that of the supply company and considerable current could flow albeit from a very low voltage.

Thinking about it more, the only 'safe' option is an RCD near source isnt it?


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so you don't earth the exposed metalwork of the van - there is a fault within your van where a live wire touches the body work - regardless of weather or not the the earth to the van in the hook up cable is present if the body work is not connected to earth you will be the earth path. similarly the RCD won't work until you make the earth path, meaning you will receive at best a shock. This is the reason why you connect the body of the van to the earth terminal in the consumer unit.

This makes more sense...however if the earth is missing in the hook up cable it still would mean the body of the van is live...fine until an earth path is found..like for example reaching out the window and grabbing a metal fence..so how does connection at the consumer unit make a difference?

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Re: Mains hook-up dangers

Post by Oldiebut goodie »

max and caddy wrote:
Oldiebut goodie wrote:If you think about what tyres are made of you will soon realize that they aren't a good insulator. (carbon black)

Rubber is a fairly good electrical insulator I reckon....they used rubber insulated cables for a good many years, and my tyres are not made of carbon although it may be an ingredient, furthermore there may not even be an electrical path to the wheel itself due to bushes and mounts if you think about it.

Ever received a static shock of a car door...not sure who is live and who is earth in that scenario.
But it isn't pure rubber which is an insulator. Path to earth via the wheel - handbrake cable isn't insulated.
Static usually builds up on our bodies and discharges to earth as we touch the metal.
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Re: Mains hook-up dangers

Post by Smcknighty »

I know tyres on a mountain bike insulate you against electric fences - I leaned on to a steel gate that was live, no impact till I got off my bike


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Re: Mains hook-up dangers

Post by max and caddy »

I'm open to proof that tyres conduct a significant amount to be considered as a conductor.

Handbrake cable...in theory yes it's a connection to the wheel...but not sure I want to stake my life on it...or my sons..I would expect resistance at best.

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Re: Mains hook-up dangers

Post by Oldiebut goodie »

From Birlacarbon.com:

Birla Carbon Rubber Blacks

Carbon black is the predominant reinforcing filler used in rubber compounds, and it is required to impart the necessary durability and strength to these products for longer lifetime and greatly improved performance. Carbon Black distributes and absorbs stress applied to a rubber component and improves its tensile strength, tear strength and abrasion resistance. Carbon Black can also impart electrical conductivity / resistivity to a rubber compound for dissipating static charge in dynamic applications such as automotive belts and Green Tires.

As the largest manufacturer of Carbon Black, Birla Carbon is an established and leading supplier of Rubber Black additives to the Tire and Mechanical Rubber Goods Industry.



Preamble from carbon-black.org:

Overview of Uses

Traditionally, carbon black has been used as a reinforcing agent in tires. Today, because of its unique properties, the uses of carbon black have expanded to include pigmentation, ultraviolet (UV) stabilization and conductive agents in a variety of everyday and specialty high performance products, including:
Tires and Industrial Rubber Products: Carbon black is added to rubber as both a filler and as a strengthening or reinforcing agent. For various types of tires, it is used in innerliners, carcasses, sidewalls and treads utilizing different types based on specific performance requirements. Carbon black is also used in many molded and extruded industrial rubber products, such as belts, hoses, gaskets, diaphragms, vibration isolation devices, bushings, air springs, chassis bumpers, and multiple types of pads, boots, wiper blades, fascia, conveyor wheels, and grommets.
Plastics: Carbon blacks are now widely used for conductive packaging, films, fibers, moldings, pipes and semi-conductive cable compounds in products such as refuse sacks, industrial bags, photographic containers, agriculture mulch film, stretch wrap, and thermoplastic molding applications for automotive, electrical/electronics, household appliances and blow-molded containers.
Electrostatic Discharge (ESD) Compounds: Carbon blacks are carefully designed to transform electrical characteristics from insulating to conductive in products such as electronics packaging, safety applications, and automotive parts.
High Performance Coatings: Carbon blacks provide pigmentation, conductivity, and UV protection for a number of coating applications including automotive (primer basecoats and clearcoats), marine, aerospace, decorative, wood, and industrial coatings.
Toners and Printing Inks: Carbon blacks enhance formulations and deliver broad flexibility in meeting specific color requirements.
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Re: Mains hook-up dangers

Post by kevtherev »

I used to make tyres for Goodyear, and I can categorically say there is a HELL of a lot of carbon black in tyres.
They are not made of rubber, they are made from synthetic rubber and are full of conductive resins
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Re: Mains hook-up dangers

Post by itchyfeet »

Earth your van chassis to the mains supply earth.
Fit an RCD as close to the incoming socket as possible inside your van.
Try to hook up to an RCD supply where ever possible
Job done.

I have had an earth leakage shock from mains via the body via me to earth from a wet inlet socket when hooked up to a non rcd supply because my van wasn't earthed ( I was standing outside leaning against the van bare footed)

Electricity largely takes the path of least resistance (which was not through my suspension and tyres) , if the van was earthed that would have been the path of least resistance.

Chances of being hit by lightening are slim and earthing your van to mains earth will make bugger all difference
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