I assume you don't mean the freezer giving shocks means the shed has no earth - there might be earth continuity right up to the point where the freezer should be earthed and if it's just a lug & crimp it could have come off - simple fix
Freezer shocks
- Thread starter Bodgeitandleggit
- Start date
I assume you don't mean the freezer giving shocks means the shed has no earth - there might be earth continuity right up to the point where the freezer should be earthed and if it's just a lug & crimp it could have come off - simple fix
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Have you measured the shock voltage ?
One person's shock is another person's tingle.
One person's shock is another person's tingle.
It clearly needs to be looked into (as others have said, merely replacing the freezer could possibly leave a potentially dangerous problem unaddressed), but I'm not sure that we really know what we're dealing with - the OP described the 'shock' he experienced as being 'like a static zap' - and I suppose it's possible that this is precisely what it was, and was experienced because the freezer was satisfactorily earthed. It should not take an electrician very long to ascertain what, if anything, is going on.
Kind Regards, John
Yup a Zs and a quick earth-freezer body continuity test should clear things up in about 5 minutes
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Maybe! I'm still wondering about all this. If the shed has a dry wooden (or whatever) floor and the OP was wearing shoes, I wouldn't necessarily expect him to get a significant shock from touching the freezer casing even if it were at 230/240V above earth. A bit more description about 'the shock' might be helpful.
Kind Regards, John
As bernard says though, one mans shock is another mans tingle.
I think the most reliable measurement would be a voltage to earth reading. I can't see it realistically being much more than 50vac
I think the most reliable measurement would be a voltage to earth reading. I can't see it realistically being much more than 50vac
To be precise it would need to be "earth" in the socket to earth as in true ground or what ever surface the person was touching when they got the shock / tingle. Or were they touching something at the same time as they were touching the freezer..
Exactly - which is why I said I'd be interested to hear a little more about the nature of the shock/tingle/zap. I'm still not convinced that it wasn't just a static discharge to an earther metal object!
Kind Regards, John
I'm not so sure about 'precise'! Surely not " 'earth' in the socket", but the casing of the freezer in question? If there were a lack of continuity between the socket's earth and the freezer casing, the pd between socket 'earth' and 'true ground' (or whatever) could be zero, even though the freezer casing was at a high potential above true ground, couldn't it?
Kind Regards, John
I expect the trouble will be that you have exported the earth from the house, and the shed is some distance away.
Inside the house you should not get a shock from the earthed casing of an appliance, because the main bonds (and probably also supplementary bonds, and lots of metallic pipes in the house) will ensure that, inside the house, you are in an equipotential zone; which means that all the earthed appliances, and probably also damp concrete floors, will be at the same potential, which means that you can touch any two of them, and there will be no voltage between them, so you will not get a shock.
Outside the house, there may very well be a difference between the potential of the ground you are standing on, and the earth wire connected to the MET in the house, which very likely will have an earth provided by the electricity company; thus you can get a shock from a nominally earthed appliance casing. The voltage may vary, and can become more or less dangerous depending on weather conditions and power usage. This problem is especially serious when there are metallic services entering an outbuilding, and in caravans which may be insulated from the earth with their rubber tyres, and so an exported earth must not be used in these conditions. Instead, a local earth spike is required.
Loss of continuity, or a loose connection, would not be the cause in such a case.
A competent electrician will know how to confirm and deal with the problem.
That's all conceptually true but, as I've been saying, I do wonder in this case. In the absence of a fault in the appliance, I would have thought that even an exported TN-C-S earth is unlikely to be at a potential sufficiently different from the floor of a shed to result in a significant shock, even if the victim had bare feet. On the other hand, an earth leakage in the appliance coupled with a long and possibly inadequate CPC could obviously result in the appliance casing being at a fairly high potential ... and all that, of course, assuming that the shocks weren't static discharges!
Indeed so. That is definitely what's needed, since there is scope for there being a potentially serious/dangerous problem afoot.
Kind Regards, John
One from the archive about shocks from apparently earthed appliances,
Mild electric shock while touching an electric urn in a chapel. The cable supplying the 15 amp socket was a long heavy duty rubber lead stapled along the wall. This cable was plugged into a 5 amp socket by the "fuse board" but the 5 amp plug was too small for the Live Neutral and Earth so only Live and Neutral were connected. Had I had a meter I expect I would have found the urn was about 115 volts above ground.
That was installed by "a qualified electricians mate"
Mild electric shock while touching an electric urn in a chapel. The cable supplying the 15 amp socket was a long heavy duty rubber lead stapled along the wall. This cable was plugged into a 5 amp socket by the "fuse board" but the 5 amp plug was too small for the Live Neutral and Earth so only Live and Neutral were connected. Had I had a meter I expect I would have found the urn was about 115 volts above ground.
That was installed by "a qualified electricians mate"
Fair enough - but, in the absence of faults, that ~115V presumably exists only because of (tiny) capacitances (to L and N/ground). Indeed, if you had a meter of sufficiently high impedance, I suppose you would similarly be able to measure ~115V to ground from any (unearthed) metal object in close proximity to (but not connected to) any electrical wiring or equipment.
However, I would have expected that (unless the person was also touching something with a reasonable path to earth) the total impedance of the path through the tiny capacitance, the person and from the person to earth (through footware, flooring etc.) would be so high that one would be hard-pressed to get enough current to flow to even feel.
Kind Regards, John
In the chapel the water tap, lead pipe up from the ground, was next to the urn so a second point of contact with very low impedance was to hand.
I wasn't allowed to do anything and was even rebuked for daring to criticise the highly respected "electrician"
I wasn't allowed to do anything and was even rebuked for daring to criticise the highly respected "electrician"
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