Live appliances

[Gwilym84]

Put on some power in the kitchen but when i touch the appliances you get a little shock. Nothing major but it vibrates on your finger tips. There is no earth from the supply to my fuseboard yet but surely this couldnt be the reason for shocks unless your not as the same potential as the appliance or could it?

 

[sparkyspike]

You can still have p.d. between appliances etc through CPCs, pipework, structural steel, appliances chassis etc. etc. unless you have an earth-free installation. Why is the power on but the earthing not yet connected?

 

[Gwilym84]

we do have an earth free installation at the moment simply because of the cable not turning up and the need for power in the kitchen. So could the fact that it is earth free at the moment be causing the casing to become live? if so how?

Thanks for a quick reply

 

[securespark]

I'm sorry to sound harsh, but you must be feeling suicidal to switch on your installation with no connection to the MET.

Why have you no connection?

Have you got an RCD?

 

[sparkyspike]

we do have an earth free installation at the moment

I doubt it.

 

[tim west]

Without earthing a class 1 appliance can develop a fault to the casing and be live for a long time if you have no earthing in your house, then you could happily go on using it unaware for years, it becomes a problem if another unearthed appliance on a different phase becomes live as well and two people touch their appliances at the same time, with enough resistance in the general mass of earth you may only end up with a few volts and miniscule current from the initial 415v and just get a tingle but its a potential dangerous situation and one of the reasons the earthing system was first devised many moons ago.
the resistance could be low if for instance supporting steelwork is buried into soft clay (london for instance has soft clay underneath).
so there is potential for a much lower resistance path and a higher voltage and current to pass through both people.