Earthing Spike and RCD

[terrysdelight]

Hi

Can anyone give me a rough cost for an earthing spike and RCD. Sparkies are in at the moment and they were trying to get the UK Power Network to supply an earth but they won't.

They are already working for me on a fixed price so this is obviously an extra - where can I find a price on the materials? How long does it take to fit an earthing spike? I understand the copper rod/spike has to go into the ground about 4ft, so not sure how long it would/could take.

Many thanks

 

[Chri5]

In London I'd expect the network operator to offer an earth with the mains supply, have you asked a neighbour what they have?

Spikes tend to variable depending on ground type, position of spike, depth required.

If your building new and doing a 4ft + foundation then it's easy

There's plates, rods, multiple rods.

I don't know the area, the local conditions or the job, so can't say hours, or cost.

Look here http://www.tlc-direct.co.uk/Main_Index/Earthing_Index/index.html

Hardly a kings ransom.

 

[EFLImpudence]

It's more than I'd pay to get a king back.

 

[terrysdelight]

Basically, UK Power Networks told me I have no earth and need earthing spike. They said they have a 6 week waiting list.

Am I reading this right, just several pounds for the spike? and about £20 for an RCD?

UKPN charge £260 pounds for this?

 

[Stevoon]

You will also want an enclosure for the rod & connection, something like this;- http://www.screwfix.com/p/plastic-inspection-earth-pit/16092

 

[terrysdelight]

Thanks, so basically a max of £50 for materials and just the labour to get a rod 4 foot into the ground?

 

[Spark123]

£20 for an RCD sounds too cheap, at least for a decent make it does.
What is the current consumer unit setup? Can you post a pic?

 

[sparkybird]

Fitting 1 RCD upfront of your fuse board is a rough solution - if it trips you loose all power and all lights. If I was your sparky I'd be upgrading the fuse board to dual RCD or even all rcbo's. To do board upgrade I'd need to test all circuits to make sure there were no faults (such as N to E, which would not cause any tripping at the moment if you have no RCD)

The testing and fuse board work is what will cost you - rather a lot more than £50...

Even if you do go down the rough route, any good electrician will still want to carry out some tests to make sure the RCD won't trip when installed

 

[flameport]

Thanks, so basically a max of £50 for materials and just the labour to get a rod 4 foot into the ground?

Yes - but only if a single rod is sufficient.

In a few instances it may be.
In plenty of others, it will be next to useless, therefore far more materials and labour would be required.

 

[terrysdelight]

Sorry there is RCD, its all new but just need to get the earth sorted out.

I just don't want to end up paying a fortune as this is an extra cost which I didn't bargain for.

 

[ericmark]

Much depends where it is being fitted. I have in the past fitted them under the floor boards.

Under fault conditions the earth rod voltage will be raised in respect to surrounding ground and there will be a gradient as you move away from the rod. So the rod and connection to it is protected for an area around it how much depends on size of rod. This is why we use an earth pit it allows access with use of a tool but children and dogs can't get too close. Also it shows where the earth rod is so it can be tested.

Because you are using 30ma RCD's rather than the delayed 100ma RCD often used with earth rods the protection around the rod is not so important as fault conditions should only last 0.04 of a second.

How deep depends on the soil normally I look for around 60 ohms although regulations allow 200 ohms (Table 41.5 Note 2) to get a high reading like that in some areas would only need a 6 inch nail.

Rods are typical 1.2 meters long and it is rare to need more than one rod to get 60 ohms.

For commercial installations then it may need multi-rods but the only reason I can see for multi rods in a domestic is for charging electric vehicles where to ensure safe gradient I personally would install a rod at each corner where the vehicle is parked and in that case being covered is not really important as you could still touch the car. TN-C-S it seems is not allowed to charge vehicles has to be TT same as with caravans.

There are two ways to measure the resistance of an earth rod. Where there is a supply from the mains a earth loop impedance meter is used. However if the rod is being fitted before the mains supply is available or using a generator then a special meter is required and common to hire these as and when required. Clearly hire cost would be passed on to you. Been a long time since I needed to hire the meter but would expect around £75 hire charge.

 

[terrysdelight]

EricMark and everyone else, thank you for the information.

 

[terrysdelight]

EricMark and everyone else, thank you for the information.