Electric leak, advice needed

[mark99]

11 hours ago, rusty69 said:

Wot is this red Harding please?

 

Silly it's a relative of the icolator......

[Hannah Jones McVey]

Thanks all, yes I felt a bit of mansplaining may be afoot, it's not the first time, it's very annoying though as I doubt I will get beyond it but your advice has really helped thank you.

[Sea Dog]

Hannah, I don't know what's going on here either but tend to agree NickNorman's "mansplaining" hypothesis.  Just a thought though... Check that you have an AC earth wire (quite thick, green and yellow) going to the hull where it should be bolted to the metal, probably on one of the big beams the engine sits on.  It should be next to another similar bolt with a black wire connecting the battery negative (perhaps via a stud on the engine) to the hull. This AC earth bond  is a requirement under the Boat Safety Scheme and the Recreational Craft Directive so, whilst some argue about its necessity (remember I said earlier about the understanding of stray currents?), it should be there and it's function is to ensure that the hull and your AC electrical earth are at the same "potential".  This can get missed - my own boat had RCD and BSS certificates, yet this bond was not present when I bought her. Worth a look.

 

[Horace42]

18 hours ago, Hannah Jones McVey said:

Hi,

 

A few weeks ago our boat came out for survey and the blacking job done since months earlier looked like it had seen better days. During investigations since the man responsible for the blacking has done an electrical leakage test and sent us this outcome

 

'

basically I don’t think there was anything switched on on the boat because the current draw was 71 milliamps and at that current the imbalance between live and neutral was 0.3 mA  . the earth wire had zero current.

This means that the imbalance current is flowing out thru your hull

Although small at this quiescent state it would likely rise when other units are switched on'

 

I am no electrician and this means nothing to me. Can someone explain it in a dummy's guide style. The boat is being sold at the end of the week and I need to know what I should do.

 

Many thanks

 

 

The zero current in the earth wire could be due to a break or bad connection in the earth conductor ....was that checked for continuity?

And as a result of the 'failure' did the surveyor carry out a full insulation test?  because it sounds to me like poor insulation of the live conductor somewhere - for all sorts of reasons as explained by others above.  

And if the 'wiring' insulation is good, then it is probably some equipment connected to it, as already suggested, so switch it off, or disconnect it, and then test.

I am not up to speed on galvanic isolators, but aren't they are supposed to prevent currents circulating through the hull and water when the boat is plugged into the shore supply?

.....and as an aside, my boat hull has just been blacked, and no mention of any electrical test.....and certainly not part of any BSS test I know of, nor the recent valuation survey I had carried out.

However in your case, for peace of mind, your wiring can easily be tested again - and in view of the effect on value - a second opinion would be useful.

 

PS: Just seen Sea Dog reply #28. Good points to check. It came in whilst writing mine so didn't see it.

Edited October 23, 2018 by Horace42
PS added.

[Flyboy]

19 hours ago, Sir Nibble said:

Do you have any neon light indicators about the place? On a spur connection for instance?

I have seen on some boats a neon connected between live & earth to act as a 'correct polarity' light. It draws enough current to deflect the meter on a galvanic isolator but not enough to trip the rcd.

[Horace42]

1 hour ago, Flyboy said:

I have seen on some boats a neon connected between live & earth to act as a 'correct polarity' light. It draws enough current to deflect the meter on a galvanic isolator but not enough to trip the rcd.

That makes sense, an in that case, would they be part of on the socket/spur. If so I cannot see how the installation would pass an insulation test, but pass or fail, the current should flow in the earth wire.

The logical advice to the OP, in terms of reliable information to support the sale of the boat, it would better to have it's accuracy traceable to a competent sources - so get the electrics tested independently - and get a certificate.

 

 

[Nut]

17 hours ago, nicknorman said:

The guy is talking rubbish. Apart from the fact that the current discrepancy is tiny and probably the result of measurement inaccuracy, the whole point of blacking is to insulate/isolate the hull from the water. So it is not feasible to suggest that this (probably imaginary) tiny current is in any way responsible for the blacking degrading. There will still be plenty of exposed metal (the baseplate, the propeller etc) which would conduct away any current much more easily than blacking (if the current wasn't imaginary!). He is simply making up an excuse for the blacking issue and probably thinks that with you being a girly he can bamboozle you with fake science. Fortunately you are sensible enough to seek advice and not take his mansplaining at face value!

I imagine this about sums it up TBH ,op they are trying to hoodwink you stand your ground

[Chewbacka]

Stray currents will increase the rate of corrosion and can speed up the rate of delamination of paint films. BUT the problem is with DC currents and yours was reported as a tiny AC current, had he found a DC current I am sure he would have told you.  The ‘painter’ whilst agreeing that the current was tiny, and not telling you the difference between AC and DC went on to say the current would get larger if more things were turned on. There is no evidence to support this.  So I think he is trying to convince you that the blacking which was done recently and doesn’t look so good is not because of poor prep and/or application on his/her part, but due to your boat...........

[WotEver]

3 hours ago, Horace42 said:

The logical advice to the OP, in terms of reliable information to support the sale of the boat, it would better to have it's accuracy traceable to a competent sources - so get the electrics tested independently - and get a certificate.

I disagree. The logical advice to the OP is to ignore the BS from the painter and to simply get on with her life, safe in the knowledge that there’s no problem. 

[Alan de Enfield]

14 minutes ago, WotEver said:

I disagree. The logical advice to the OP is to ignore the BS from the painter and to simply get on with her life, safe in the knowledge that there’s no problem. 

But the OP is selling the boat and has already been 'beaten down' by £700 (if I have read it right - apparently because of the 'report')

 

"I am saddened you think it's poor application, I agree but the bloke who did it doesn't, have already lost £700 off the negotiations as a result."  

Edited October 23, 2018 by Alan de Enfield

[WotEver]

42 minutes ago, Alan de Enfield said:

But the OP is selling the boat and has already been 'beaten down' by £700 (if I have read it right - apparently because of the 'report')

 

"I am saddened you think it's poor application, I agree but the bloke who did it doesn't, have already lost £700 off the negotiations as a result."  

No, that reduction was due to the poor blacking as I understand it. 

[Horace42]

16 hours ago, WotEver said:

I disagree. The logical advice to the OP is to ignore the BS from the painter and to simply get on with her life, safe in the knowledge that there’s no problem. 

I don't mind what action the OP takes, by all means ignore the problem, but it's seems to be a worry enough to pose the question here, leading to what the prospective buyer thinks about the effect on value - assuming they are in possession of the facts about the blacking/electrics.

Either way, there has to be an explanation about where the stray current is going - if there is any at all - and if taken at face value, as seems to be the case here - (assuming the provenance of the instrument accuracy, the protocol used, and competency of the tester, is reliable) - then what effect if true, do the results have on the blacking/anodes - then boat value - all in the mind of the buyer?

Personally I would be inclined to agree with WotEver - but it's not my boat or money at stake.

 

 

[Chewbacka]

The story as I understand it and please correct me if I am wrong is the boat is to be sold, it was taken out for a survey and no electrical problems identified by the surveyor however the blacking which was ‘recently done’ did not look good and so the price was reduced accordingly (£700).  The person that did the blacking explained that the condition of the blacking was not down to poor prep/application but was due to a leakage current that would be worse when the boat had more appliances turned and therefore not their responsibility.  

 

As the steel hull is reported as in good condition and no evidence of pitting which is a common side effect of excessive leakage current reported I am further suspicious of the reason given for the poor condition of the blacking.  Without getting an electrical survey done and an inspection of the blacking - for example confirmed as not attacked by diesel on the canal - it will be difficult to a demonstrate that the blacking was defective.  

[Richard10002]

9 hours ago, Chewbacka said:

The story as I understand it and please correct me if I am wrong is the boat is to be sold, it was taken out for a survey and no electrical problems identified by the surveyor however the blacking which was ‘recently done’ did not look good and so the price was reduced accordingly (£700).  The person that did the blacking explained that the condition of the blacking was not down to poor prep/application but was due to a leakage current that would be worse when the boat had more appliances turned and therefore not their responsibility.  

 

As the steel hull is reported as in good condition and no evidence of pitting which is a common side effect of excessive leakage current reported I am further suspicious of the reason given for the poor condition of the blacking.  Without getting an electrical survey done and an inspection of the blacking - for example confirmed as not attacked by diesel on the canal - it will be difficult to a demonstrate that the blacking was defective.  

My understanding is similar. The guy who did the blacking seems to be defending a criticism of his blacking which has cost the OP £700. Presumably, the surveyor said that the blacking is inadequate and needs doing, and the OP has made an allowance for this, despite having the boat newly blacked only a short time ago. Presumably, if the surveyor had suspected that the poor quality of the blacking was due to something electrical, the survey would have reflected this.

 

Personally, having agreed to allow a reduction of £700 to allow for the blacking issue, I would hope to get on with the sale, take the money, hand over the boat, and get on with my life. I would expect the buyer to have a really good job done of the blacking with the £700 I have given them, and to have no further issues until it needs blacking again in a couple of years.

 

Of course, if the OP has made the buyer aware of the painters dubious excuse, thus opening an unnecessary can of worms, anything could now happen - but I am not reading that this is the case.

[ditchcrawler]

And if I read it right the painter has the test equipment and knowlage to test the electrical system and say it has a leakage of was it 0.3ma. I am not sure what I would use to measure that sort of live neutrals imbalance

Edit to add

 

maybe he has one of these at about £500 and the knowledge to use it https://www.tester.co.uk/fluke-369-fc-wireless-leakage-current-clamp-meter-61mm-jaw?gclid=Cj0KCQjwsMDeBRDMARIsAKrOP7EWG4d56XchjRQnOePLysvWFgLFmwuUHOSHrqa-F3Djl5ow1t8UtjsaAoceEALw_wcB

Edited October 24, 2018 by ditchcrawler

[Alan de Enfield]

10 minutes ago, ditchcrawler said:

And if I read it right the painter has the test equipment and knowlage to test the electrical system and say it has a leakage of was it 0.3ma. I am not sure what I would use to measure that sort of live neutrals imbalance

Edit to add

 

maybe he has one of these at about £500 and the knowledge to use it https://www.tester.co.uk/fluke-369-fc-wireless-leakage-current-clamp-meter-61mm-jaw?gclid=Cj0KCQjwsMDeBRDMARIsAKrOP7EWG4d56XchjRQnOePLysvWFgLFmwuUHOSHrqa-F3Djl5ow1t8UtjsaAoceEALw_wcB

Or, maybe he just guessed ?

 

I cannot imagine that many painters would have, and know how to use, such electrical test equipment - it would appear to be so far removed from their primary skill-set.

[Richard10002]

Just now, Alan de Enfield said:

Or, maybe he just guessed ?

 

I cannot imagine that many painters would have, and know how to use, such electrical test equipment - it would appear to be so far removed from their primary skill-set.

In fairness, he might run a boatyard, and have a variety of boat related skills. However, the consensus here seems to be that what he has found is something and nothing and, even if it is something, it is highly unlikely to have caused the deficiencies in the blacking.

 

Given the variety of knowledge and expertise here, I have more faith in responses here than in what appears to be an excuse for poor blacking.

[Horace42]

15 minutes ago, Alan de Enfield said:

Or, maybe he just guessed ?

 

I cannot imagine that many painters would have, and know how to use, such electrical test equipment - it would appear to be so far removed from their primary skill-set.

I have a DC clamp meter. Hardly ever us it. Forgot the name. Can't find the manual. Hall Effect I think. It can show a mA reading waving it in the air near the cable before I clamp it over the cable, then it goes to zero when the clamp closes - if the cable circuit is switched off.

And considering I can only check for one cable at a time - makes me wonder if the painter took current readings in 3 cables taken at different times - and then compared them on the assumption they had remained exactly constant for the time it took to do the test. Or worse, if a simple ammeter was used, then the cables would have to be disconnected to insert the ammeter in series. 

Any one who has done this will know it is quite difficult.

[Sea Dog]

If you want to reassure the buyer that this phantom  "electric leak" is no longer a problem... show him a receipt for a plug.

 

An alternative might be to have the boat re blacked elsewhere, then sell her having corrected what was raised in the survey report and draw a line under this issue.  Did you check the boat had the required AC earthing arrangement in place?

[Chewbacka]

10 hours ago, ditchcrawler said:

And if I read it right the painter has the test equipment and knowlage to test the electrical system and say it has a leakage of was it 0.3ma. I am not sure what I would use to measure that sort of live neutrals imbalance

Edit to add

 

maybe he has one of these at about £500 and the knowledge to use it https://www.tester.co.uk/fluke-369-fc-wireless-leakage-current-clamp-meter-61mm-jaw?gclid=Cj0KCQjwsMDeBRDMARIsAKrOP7EWG4d56XchjRQnOePLysvWFgLFmwuUHOSHrqa-F3Djl5ow1t8UtjsaAoceEALw_wcB

I was not saying the painter was wrong when he said there was a leakage of 0.3mA AC just that I am a little sceptical that this would have caused the blacking to fail in a short time.

[Sir Nibble]

This is something that it's difficult to be definitive about unless one is a specialist. There may well be a testing regime of which I am unaware that would throw up such a result. It could be that such a test is part of proving the electrical system but incredible that no one here would be aware of it if so. I would test L/N, L/E and N/E with a Megger expecting greater than one megohm on each, the same as a domestic installation. The test actually carried out and the result seems slanted towards detecting galvanic current which would make sense in the context of the bloke doing the blacking covering his arse. .3 mA may be normal for a boat connected to a shoreline for all l know, and that's why we fit galvanic isolators.

[ditchcrawler]

On ‎25‎/‎10‎/‎2018 at 00:36, Horace42 said:

I have a DC clamp meter. Hardly ever us it. Forgot the name. Can't find the manual. Hall Effect I think. It can show a mA reading waving it in the air near the cable before I clamp it over the cable, then it goes to zero when the clamp closes - if the cable circuit is switched off.

And considering I can only check for one cable at a time - makes me wonder if the painter took current readings in 3 cables taken at different times - and then compared them on the assumption they had remained exactly constant for the time it took to do the test. Or worse, if a simple ammeter was used, then the cables would have to be disconnected to insert the ammeter in series. 

Any one who has done this will know it is quite difficult.

You don't, you put it round the mains live and neutral conductors simultaneously and if they are in balance you get a reading of zero as they cancel each other out, but if some current is going somewhere else its an imbalance and that would show up if your instrument is sensitive enough.  You would probably need to go into the consumer unit to be able to access just live and neutral and to have the consumer unit live while you did it. Or you could strip the outer insulation off the landline, separate the cores so you just capture L&N and tape it up afterwards.

[Horace42]

14 hours ago, ditchcrawler said:

You don't, you put it round the mains live and neutral conductors simultaneously and if they are in balance you get a reading of zero as they cancel each other out, but if some current is going somewhere else its an imbalance and that would show up if your instrument is sensitive enough.  You would probably need to go into the consumer unit to be able to access just live and neutral and to have the consumer unit live while you did it. Or you could strip the outer insulation off the landline, separate the cores so you just capture L&N and tape it up afterwards.

Thanks for your feedback. Yes you are right - clamp the whole cable - I should have been paying attention. But my mind was distracted by the 0.3mA current difference, and finding where it was going when the earth wire current was said to be zero. It would take time to intercept the cables to make measurements - with meter readings leading to answers based on the assumption the 'load' was constant for the time it took to do the test.

And if on the whole power supply cable (at source rather than on the boat) it could be poor insulation and leakage to earth before reaching the boat.

There are too many unknowns here.

It would be interesting to hear what the OP has decided to do.

 

 

[Chewbacka]

The op will probably do nothing as the boat was surveyed prior to sale, so the boat is best left alone.

[ditchcrawler]

8 hours ago, Horace42 said:

Thanks for your feedback. Yes you are right - clamp the whole cable - I should have been paying attention. But my mind was distracted by the 0.3mA current difference, and finding where it was going when the earth wire current was said to be zero. It would take time to intercept the cables to make measurements - with meter readings leading to answers based on the assumption the 'load' was constant for the time it took to do the test.

And if on the whole power supply cable (at source rather than on the boat) it could be poor insulation and leakage to earth before reaching the boat.

There are too many unknowns here.

It would be interesting to hear what the OP has decided to do.

 

 

Not the whole cable, just live and neutral  then if you have 3 amps flowing in. 0,03 flowing to earth you end up with2.97 in the neutral and if you have a £500 clamp meter you measure 0.03 amps. As I said he is going to have to take things to bits to carry out the measurement if he has the right equipment