EHU cable

[Otter Spotter]

I now have my man shed and I want to set up a mains cable with socket for plugging van into, so what amperage of cable from fuse box to socket and should I fit an inline fuse for this set up ?
Cheers in anticipation

 

[Dave and Jen]

Hi, Dave, I think you could use a length of hook-up cable, probably depends how far away the fusebox is, I'm sure someone will be along soon to give you more details.
Cheers, Dave

 

[meanders]

Do you want any other services in the shed? How far away is the shed from the incoming mains and how does the land lie? Ideally I would run in an armoured cable and put in a small distribution unit in the shed with a spur off to a ceeform with 16a trip and RCD. It's also possible to provide via a catenary overhead, but neither is really a DIY option as you need a Part P certificate.

 

[autorouter]

I think I'd be looking at putting one of these on the outside of the shed. It has a 16A double-pole RCBO that protects against electric shock, earth leakage and overcurrent. How you supply it is another question. I think I'd use 2.5mm² cable at least to supply it. As has been said it depends what other items will be supplied. Maybe get a small 'garage consumer unit' inside the shed, and have the hookup box on one of the MCBs.

Hook Up Unit

• IP44 Hook Up Point • 1 gang unmetered • Made to the latest UK regulations• Pre wired with Tri rated cables • Double Pole RCBOs 30mA• Compliant MID approved meters (where fitted, enabling you to charge for electricity usage )• Pre fitted with 35mm loop in and out terminals as standard•...

www.toolstation.com

 

[StephenW]

When I had a power supply installed for my shed the electrician provided a small consumer unit, lighting, double socket and hook up point. To ensure that the supply was at least 13amps we needed to use 6 or 7mm armoured cable (can’t remember which) as the distance was around 50m

^{_{Subscribers  do not see these advertisements}}

 

[xsparks]

The option would of been 6 or 10

 

[Bern8]

RCD should be inside the house to protect everything leaving the house (you should only have 1 rcd on the circuit).
Armoured cable is best but single cable can be run inside a conduit. Size of cable depends on length of run (volt drop).
As already stated certain parts of installation around your property should be Part P certified and outdoor work comes under that umbrella.

 

[Otter Spotter]

Do you want any other services in the shed? How far away is the shed from the incoming mains and how does the land lie? Ideally I would run in an armoured cable and put in a small distribution unit in the shed with a spur off to a ceeform with 16a trip and RCD. It's also possible to provide via a catenary overhead, but neither is really a DIY option as you need a Part P certificate.

Shed already has power via armoured cable, which is used to supply lighting and 3 pin sockets via a single fuse box. What’s a ceeform .

 

[Gromett]

I don't think this is a DIY job these days? From memory it is Part P and most work other than minor repairs needs to be done by a qualified person these days?

 

[Otter Spotter]

Reading all your replies, it’s obviously not a DIY job so I will get a sparky in, there are a few other small jobs for him to do inside the house, like replacing fans in both bathroom and kitchen, and replacing some single with double sockets. Thanks for all your replies, you have saved me from potentially killing myself

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

Shed already has power via armoured cable, which is used to supply lighting and 3 pin sockets via a single fuse box. What’s a ceeform

In that case one of those hookup boxes I linked to could be put on the outside, taken from an extra MCB in the existing shed fuse box. Not a big job, I would have thought.

Those round blue 16A plugs and sockets used for hookup are called various names, including ceeform because they are to CEE Specification. Also called Commando sockets in the UK.

 

[meanders]

What’s a ceeform .

The blue connectors we use for EHU hookup. Commonly also called Commando plugs in industry, except in entertainment where they are always Ceeform's (apart from America where they are 'pin and sleeve'! Entertainment also often have the 16a blue one completely black.as they provide the feed for most, (but not all lights). That's so they don't stand out in the lighting rig under blue lights . 'Blues', (traditionally Congo Blue) are always used on stage for scene changes etc as, provided they are not projected onto white, they cannot be seen against a black tab but still give enough light to move set, and move about safely. If you put a blue light onto a blue connector, it looks almost white! Such fun we have with colours. The technical room is often called the Blue Room as distinct from the Green Room for the actors etc.

Edit: autorouter' more succinct answer beat me to it.

 

[autorouter]

RCD should be inside the house to protect everything leaving the house (you should only have 1 rcd on the circuit).

If you can only have one RCD on a circuit, then the best way is to have just an MCB at the house consumer unit (CU) end, not protected by the house RCD. This can go to a CU in the shed, with an RCD and MCBs, but with another 16A MCB not protected by the shed RCD. Then the wire goes from that 16A MCB to the hookup box, which has its own RCD and double-pole 16A MCB, or better a double-pole 16A RCBO.

The items in the house and shed CUs can be standard UK stuff, single pole MCBs. But the items in the hookup box need to be double-pole types, as in my link in post #4.

 

[Gromett]

you should only have 1 rcd on the circuit

Why is that?
In my Van I have an RCD. This connects to the RCD on the post, which then connect to the RCD in the owners electrical panel.

That is 3 RCD's in the circuit. I don't see the issue with having multiples?

 

[meanders]

There is a distinct possibility of confusion, and possibly danger if the user cannot understand what is happening, ie. Why have I been plunged into darkness. That trip hasn't dropped, starts poking about live circuits in the dark.

It's certainly undesirable and some would say is in breach of regs. Ideally, the trip pattern of each RCD would be selected auch that it's always the last in the chain that would trip first. Certainly the little inline RCD's you get as a "plug" on an extension should have a faster activation time than the typically 30ms one in the distribution board. (Aka Consumer Unit), but may not be.

I always use an in-line RCD when using power tools outdoors. When my better half cut through the cable to the hedge trimmer with it, it was the in-,line device the tripped, not the one back at the board.

Others may argue, but apart from confusion, I do not believe there is an inherent risk.

^{_{Subscribers  do not see these advertisements}}

 

[Happy Jack]

Please be aware.
Although I see you have decided to call in a leccy.
It's not just regs to conform with, it's illegal to do it yourself.
Happy Jack.

 

[DBK]

Being a cheapskate I used 1.5mm armoured cable buried in the ground between a socket beside the van and a little RCD consumer unit in my shed. It is connected to a 6A RCD which is more than enough to keep the batteries topped up and run the fridge before a trip. It's worked well for years.

 

[Bern8]

RCD’s work off a rating of mA. So my first point would be if you have a 30mA in the house and a 30mA in the shed then it is costing you money that you don’t need to spend as both should trip at the same time.
Installing a cable from the house to the shed should ideally be protected. Just putting the RCD in the shed will not protect anyone who puts a spade through the cable. If the RCD is in the house then any cable to the shed and any circuit from a consumer unit in the shed will all be protected by the RCD in the house. As posted earlier if you have multiple RCD’s in the circuit it can become confusing. Depending on the mA rating of each device will depend on how quick it trips.

 

[autorouter]

There is the other side to the argument - if there are multiple RCDs in a circuit, then if one of them fails to work, one of the others will still protect you. RCDs have a test button for a reason, they should be tested periodically. If they need testing, that's because there is a possibility they won't work.

And as for causing confusion, most people don't even know the difference between an RCD, MCB and RCBO anyway

 

[Brize]

I had something similar done a couple of years ago so that I could plug in the MH.

Good that you are going to use a sparky. My only bit of advice is to get him to fit an isolation switch to the external unit, so that no one can use it whilst you are travelling.

Hope that helps!

^{_{Subscribers  do not see these advertisements}}

 

[Otter Spotter]

I had something similar done a couple of years ago so that I could plug in the MH.

Good that you are going to use a sparky. My only bit of advice is to get him to fit an isolation switch to the external unit, so that no one can use it whilst you are travelling.

Hope that helps!

Isolation switch in kitchen for shed power and I cannot stop my wife switching it off, she doesn’t like the red light

 

[Gromett]

RCD’s work off a rating of mA. So my first point would be if you have a 30mA in the house and a 30mA in the shed then it is costing you money that you don’t need to spend as both should trip at the same time.

You can get trips that trip at different rates. You put the fast one in the shed and the slower one in the house. It is relative, they are both still very fast.

Then if there is a fault outside which is more likely (due to rain/water) it trips first and don't knock the entire house out.
The house RCD still protects the armoured cable to the shed which is unlikely to happen but best to be protected anyway.

Jim had this done at his campsite because the number of campers with slightly elevated leakage meant that if enough vans turned up it would trip the house not the post.
The sparkie changed the breakers at the post for the fast ones and the one in the house to the slow one. I don't know the details of the different types or what the actual technical details are but it sorted the issue.
Anything that happened on the campsite caused the post to trip not the one in the house. Any sparkie should be able to do this for you.

 

[Brianmor]

Unless it's changed in the last couple of years you won't know how long it will take for an RCD to trip till you buy it and test it. The only parameters you used to have is that it would trip within 40ms at 150mA or 5x operating current. This is unlike MCBs that have different time operating characterisitics ie type A,B,C or D

 

[Gromett]

Unless it's changed in the last couple of years you won't know how long it will take for an RCD to trip till you buy it and test it. The only parameters you used to have is that it would trip within 40ms at 150mA or 5x operating current. This is unlike MCBs that have different time operating characterisitics ie type A,B,C or D

I didn't know what the details were as I stopped being a sparky in the mid 90s and RCD's weren't really a thing back then on the properties I worked on.

I just did a quick google and it may be this? But I don't know. I just know that what the Sparkies did at Jim's campsite sorted the issue so the post tripped not the house.

How quickly should a RCD trip?

AS/NZS 3760:2010 specifies the maximum “trip time” a RCD must switch off the power to the circuit along with the recommended frequency of testing. Type 1 RCD’s shall trip at no greater than 40 milliseconds at a test current of 10mA a.c.

www.appliancetaggingservices.com.au

 

[Gromett]

Unless it's changed in the last couple of years you won't know how long it will take for an RCD to trip till you buy it and test it. The only parameters you used to have is that it would trip within 40ms at 150mA or 5x operating current. This is unlike MCBs that have different time operating characterisitics ie type A,B,C or D

Bit more googling. But I am sure there are some experts that will come along and correct me

Standard RCD are 30ma. so putting a 20ma or 10ma in the garage would achieve? Not necessarily a socket like this, just an example.

PowerBreaker Metalclad 2 Gang 13A Switched RCD Socket - Active 10mA | UKES

Great deals on PowerBreaker, including this Metalclad 2 Gang 13A Switched RCD Socket - Active 10mA (K22MPAAN10-C)! Shop now, FREE DELIVERY on orders over £75.

www.ukelectricalsupplies.com

^{_{Subscribers  do not see these advertisements}}

 

[Brianmor]

High risk areas usually have 10mA or 20mA, schools used to use a lot of these We used to find that a lot of 30mA RCDs used to trip with a lot less than 30mA.
Also RCDs trip with cumulative small currents as if a small previous current was held in memory till the next small current was registered and totalled near the 30mA max and then trip.

 

[Bern8]

In the case of Jim’s site, I would have thought a 100mA would be fitted at source and 30 mA or less at the post. If you go to 10mA they can trip at the slightest leakage (which is good where a damp field is concerned) but people will soon get fed up if it needs resetting regularly. We used type C & D mcb’s where load was taking time to settle down (transformers & motors). The characteristics won’t let the mcb trip for a longer period of time on start up.

 

[MisterB]

Digging your own trench for the cable will save a bob or two ....