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Author Topic: Earthing a Metal Shed - How Please?  (Read 6750 times)

Norseman

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Earthing a Metal Shed - How Please?
« on: July 04, 2011, 12:14:04 pm »

Hi

I've erected a 10' x 13' metal shed at the far end of the garden - I need space to actually work on my old german scooters rather than just store the parts for another five years!!!
Power is just going to be an extension lead - no permanent sockets or lights. However careful I might be there is always the chance of some electrical mishap {:-{, so I wonder how I might earth the shed? It's bolted to a concrete floor by the way. Any suggestions much appreciated.

Regards Norseman
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chingdevil

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Re: Earthing a Metal Shed - How Please?
« Reply #1 on: July 04, 2011, 12:32:35 pm »

A copper stake into the ground and an earth strap running from the shed to the stake would do the trick, just remember the new regulations regarding new electrical installations in a garden. It has to be done by someone with the relevent certificate, the number which escapes me.


Brian
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RaaArtyGunner

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Re: Earthing a Metal Shed - How Please?
« Reply #2 on: July 04, 2011, 12:43:14 pm »

It's already earthed.

However you can always drive a metal spear, say 600mm long, such as a copper rod, galvanised water pipe etc, into the ground against the slab and connect, with metal clamp,  heavy gauge wire from the wall sheeting to the metal spear. If sheeting is not metal then run the wire from the steel frame. The aim is to transfer any short circuit etc to ground.

Also why not connect the extension lead to the shed via a portable outlet fitted with an Earthcore Leakage Circuit Breaker. Don't think there will be a problem with the shed but with the power tools, hence a safety breaker to protect YOU from short circuits etc.

Works in OZ but we are upside down here.

Brian beat me to it.
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Paul S

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Re: Earthing a Metal Shed - How Please?
« Reply #3 on: July 04, 2011, 01:13:43 pm »

Hi ya.

The relevent electrical regulation is Part-P.  Basically these days you can't make any permanet instalations or modifications without it. 

If your using a extension lead make sure that it either plugs into an RCD protected socket or if not fit it with a RCD Plug:
http://www.screwfix.com/p/masterplug-rcd-adaptor/63731
With these as soon as they detect earth leakage to ground of 20mA they cut off the supply.

Cheers

Paul
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Corposant

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Re: Earthing a Metal Shed - How Please?
« Reply #4 on: July 04, 2011, 04:36:55 pm »

Norseman

It's crucial that you take Paul's advice. The Part P regulations form part of the Building Regulations and consequently have statutory status. (You can be prosecuted if you contravene them.) The amount of electrical installation work you can do yourself is very limited - for anything in the kitchen, bathroom or outdoors, you need to inform the local council and they will charge for inspecting any work you do - making it cheaper to employ an electrician in the first place! (I speak from experience!)

If your shed is well earthed, it means that an electrical fault is very likely to blow a fuse or trip a breaker. If, however, you make contact with a live wire and also with something that is well earthed, you will stand a good chance of being electrocuted. Depending on which path through the body the current flows, it takes relatively few milliamps to kill you! Remember the old maxim: "It's volts wot jolts but it's mills wot kills".

Using an extension lead in your shed won't contravene any regulations but, as Paul says, RCD protection will limit any current flowing through you to 20mA.

Mike
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john s 2

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Re: Earthing a Metal Shed - How Please?
« Reply #5 on: July 04, 2011, 08:29:40 pm »

Depending on the age of your main fuse box. You may be well protected already.Look to see if on the fuse
box the main on/off switch is an rcd. This will have a test button to test its trip action. If fitted everything in the
house is covered including mower leads.Think of it like a pair of scales in balance. power in balences power
out.If any power starts to go through you or elsewhere the scales become out of balence and power will
be tripped in milli secs, so protecting you.It actually uses two coils in balance.Without one of these devices all
earthing the shed will acheive is a better flow of volts through you to earth possibly resulting in death.John.
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Norseman

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Re: Earthing a Metal Shed - How Please?
« Reply #6 on: July 04, 2011, 09:56:10 pm »

Hi All - thanks

Ok so I can quickly improve my safety with an RCD plug, and I can drive a spear into the ground and bond across to the shed's metalwork. At the moment I want to stick with the extension lead just to avoid any argument over my having made an electrical installation. as to my house - it has a very old consumer unit and an upgrade would definitely be a good idea - at that time it might be also be a good idea to get my four outbuildings wired up to the mains by a qualified electrician.

Regards Norseman .............. I'm just off to work now :((
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gondolier88

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Re: Earthing a Metal Shed - How Please?
« Reply #7 on: July 05, 2011, 06:47:16 pm »

A point that everyone who is hung up on Part P(who are correct in everything they say regarding qualificatioins) is missing- the electrical supply in your shed is a manufactured extension lead that 'should' be double earthed. Hence, any mishap you have will be from this lead or power tools, as you say; to stop any 'mishaps' causing your shed to become a mini Blackpool you want to earth it- great idea- however any work you do regarding earthing the shed does not have to be inspected or installed by a 'minimum Part P' registrered installer. Why? Because your shed isn't supplied with electric from a mains circuit- it is supplied from a secondary circuit, which your only responsibility is to use safely, therefore any earthing you do to the shed would only have to 'work', you wouldn't be required to use earth wire, any decent solid core cable will do. Earth clamps are pence, so no need to scrimp there, and as far as earth rod goes- a short length of 15mm copper pipe will do just fine.

Greg
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Norseman

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Re: Earthing a Metal Shed - How Please?
« Reply #8 on: July 06, 2011, 05:23:05 am »

Thanks Greg

all the replies have decided me what to do in the short term - but also made me realise I need an electrician to look over my house in general (been here 25 years but no inspection). Then to whatever work needs doing inside (minimum of a new consumer unit) I will have him add a circuit to my out buildings. I'm just waiting for Feb' to see what my employment situation is - Network Rail are going to make redundancies and my team may well be on the list - 33 years service will count for absolutely zip.

Regards Norseman
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