i put my hand in my pond and got a tingle [250mV dc] the only electrics on the pond is a live cable going to another pond
has anyone got an explantion for this
has anyone got an explantion for this
electricity in pond
- Thread starter billybob150811
- Start date
Sponsored Links
How did you measure it?
i have a multi meter and i put the two probes in the water about 25mm apart i put it on ac as well but didnt get a reading
What about one probe in the water and the other in the ground where you were standing/kneeling?
Switch off the supply to the cable and have the situation investigated.
Switch off the supply to the cable and have the situation investigated.
Sponsored Links
Long shot but maybe an electrochemical reaction between the multimeter probes? I know this is a kind of science teacher answer (never earned any money dealing with leckie but can tell you all about it) but given the readings, well?? Longer shot, tiny electric eels? I hear they are good at keeping the mosquito larvae down. Actually eels are DC so you wouldn’t get a reading.
I am not an electrician but if you put both probes in to the same pool of water, surely you shouldn't get a reading?
- Joined
- 17 Aug 2010
- Messages
- 2,739
- Reaction score
- 452
- Country
Well, apparently the meter read nothing, so --- no. It seems [250mV dc] was a random guess... not a measurement.
- Joined
- 27 Jan 2008
- Messages
- 23,618
- Reaction score
- 2,661
- Location
- Llanfair Caereinion, Nr Welshpool
- Country
One can generate electricity
show is an electric citron, but in the main it needs power from some thing a bit bigger to feel it. Around 24 volt is where you start to feel it, a wagon covered with salt and grit has given me a tingle.
But the direction is hard to work out, is the ground live and pond earth, or the ground earth and pond live?
We tend to use a TN-C-S earthing system, to ensure enough current can flow to rupture a fuse or trip an MCB. But it is not always at true ground voltage, so outside we try to use class II equipment, so although an earth is run, there is no metal to earth, so if the DNO earth is not a true earth, in the house like the bird on the electric wire no problem, but in the garden we try to not use the DNO earth.
There are loss of PEN detectors which can switch off first power then earth in the event of a fault, all well and good with an EV charging point where allowed up to 70 volt, but 25 volt can kill a cow (because legs so far apart) so hot tubs, ponds and the like either use TT i.e an earth rod, or have no earth.
But manufacturers do not need to print on the box, for use with TT earthing only, so one rouge flood light can cause problems. The major problem is an RCD will not trip if the DNO earth is not at earth polarity. If there is a leakage from live to earth yes it will trip, but not between two earths.
So it really needs some one trained to find the fault. And quick as could be fatal.
show is an electric citron, but in the main it needs power from some thing a bit bigger to feel it. Around 24 volt is where you start to feel it, a wagon covered with salt and grit has given me a tingle.But the direction is hard to work out, is the ground live and pond earth, or the ground earth and pond live?
We tend to use a TN-C-S earthing system, to ensure enough current can flow to rupture a fuse or trip an MCB. But it is not always at true ground voltage, so outside we try to use class II equipment, so although an earth is run, there is no metal to earth, so if the DNO earth is not a true earth, in the house like the bird on the electric wire no problem, but in the garden we try to not use the DNO earth.
There are loss of PEN detectors which can switch off first power then earth in the event of a fault, all well and good with an EV charging point where allowed up to 70 volt, but 25 volt can kill a cow (because legs so far apart) so hot tubs, ponds and the like either use TT i.e an earth rod, or have no earth.
But manufacturers do not need to print on the box, for use with TT earthing only, so one rouge flood light can cause problems. The major problem is an RCD will not trip if the DNO earth is not at earth polarity. If there is a leakage from live to earth yes it will trip, but not between two earths.
So it really needs some one trained to find the fault. And quick as could be fatal.
Taking posts #1 and #3 together, I thought he meant that he got a reading of 250 mV with the meter on a DC range but 'nothing' on an AC range ?
Kind Regards, John
I'm not suggesting that this is what the OP is observing, but one can get a potential difference between two points in a mass of water just as between two points in a conductor of non-zero resistance/impedance.
Imagine a narrow trough full of water with electrodes immersed in the water at each end and, say, 100 V applied between those electrodes. A current would flow between those electrodes, through the water (a very small current if it was fairly pure water).
You would then have a potential gradient in the water between the two electrodes. if you put one of the probes in the water near one of the electrodes, and the other probe somewhere else, you would see (and measure) a pd between the two probes which would gradually increase as the second probe got closer to the other electrode, which would approach 100V when the second probe got close to the second electrode. If the distance between the two probes was half of the distance between electrodes, you would see a voltage of roughly 50V between them.
Albeit in soil rather than water, it's similar to the hazard to large four-legged animals that exists when there is a significant potential gradient through the soil they are standing on (e.g. due to large currents flowing into a nearby TT earth).
Kind Regards, John
- Joined
- 17 Aug 2010
- Messages
- 2,739
- Reaction score
- 452
- Country
Yes, that makes more sense.
Wow John, never considered horses etc. Yes with a human’s gate, you may not feel it, esp with rubber soles. It sounds terrifying either way. Here’s a thought, as we still haven’t fully ascertained the AC/DC aspect, meter range etc, what about this…
If there was an accidental lack of connection to earth at the feed end before both ponds, the earth conductor in all the cabling (CPC) would be floating and therefore subject to induced voltages from Line and Neutral within in the same insulation. So, if the CPC was connected to the ponds’ liners/pumps/lights, might there not be a low current, 50V-ish? AC voltage present with respect to earth? Thinking if it was a plastic pond liner with quite dry soil around it possibly? I think I might try and check what resistances there are between the house’s main earth terminal and the ponds’ earth points maybe.
If there was an accidental lack of connection to earth at the feed end before both ponds, the earth conductor in all the cabling (CPC) would be floating and therefore subject to induced voltages from Line and Neutral within in the same insulation. So, if the CPC was connected to the ponds’ liners/pumps/lights, might there not be a low current, 50V-ish? AC voltage present with respect to earth? Thinking if it was a plastic pond liner with quite dry soil around it possibly? I think I might try and check what resistances there are between the house’s main earth terminal and the ponds’ earth points maybe.
Indeed - and that's why there are particularly demanding regulations in situations in which 'livestock' may be walking about. Without specific precautions, under certain fault situations, it's not impossible that a dangerous (potentially fatal) potential difference can arise between the front and back 'feet' (hooves etc.) of horses and cattle etc.
As has been said, I think the first things you should do are:
(a)... see what you can measure with one probe in the pond and another in (or attached to something metallic in) the surrounding soil, and
(b).. see what measurement you get [with both probes in pond, and also per (a) above) when you switch off the supply to the cable.
It's most probable that the voltages you have measured are not 'real' but, even if they were, are themselves of a very trivial magnitude (certainly not, in themselves, a safety risk) - but it would be as well to get to the bottom of what is going on, just ibn case (very unlikley) it is an indictot of a more important/serious issue.
Kind Regards, John
Edit: typos corrected
Last edited:
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
