Fitting a galvanic isolator

[blackrose]

On 06/05/2020 at 10:01, nicknorman said:

This statement in the safe shore brochure makes me realise that safe shore don’t have a clue what they are talking about:

 

“15 amps, 30amps, 70 amps, 100 amps? What does it mean? A question we are asked all the time. Basically the amperage rating of the isolator is the amount of current the isolator can handle under severe fault conditions. The isolator must be able to handle more than the available current supplied to the boat. Usually UK marina supplies are either 16 or 32 amps so the isolator must be able safely handle at least 20% more than the maximum current available to comply with legislation. Realistically the higher the rating the more reliable the isolator”

 

If they imagine that a 16A shore connection socket can only supply 16 x 1.2 = 19.2A under “severe fault conditions” they are barking. More like a few 1000A.

 

They are confusing the “legislation” for over-rating current carrying capability of power conductors, with a possible maximum short term fault current, which is a totally different thing. No wonder the ABYC standard doesn’t get a mention! They may protect up to 2 volts or whatever, but I bet at the first sign of a short circuit to earth they will disappear in a puff of smoke.

 

As an owner I posted this to Safeshore and got the following reply:

 

Ratings stated are continuous rating. Pulse ratings are significantly higher. With over 24000 isolators now currently in use we have no reported failures of any isolators. 

[blackrose]

19 hours ago, nicknorman said:

It’s to do with what happens if you have a short circuit from live to earth on your boat.

 

If that doesn’t happen, your non-ABYC compliant GI will do just the same job as a ABYC-compliant one.

 

If it does happen, your 16A supply can in fact deliver perhaps 1000A instantaneous current. Of course after a few 10s of milliseconds of that, one would expect the breaker on the bollard to trip. But 1000A going through the diode, even for a very short period of time (10mS), may melt the diode (the actual semiconductor junction is very small and thus has very small thermal mass). If the diode fails open circuit, it means your boat is no longer earthed, but you don’t realise it. I guess it might even be possible for the diode to melt and go open circuit before the breaker trips and the breaker then decides it doesn’t need to trip, so the hull becomes live.

 

Anyway the point being that an ABYC compliant GI can survive a pretty high fault current and if it does fail, it is guaranteed to fail short circuit so the boat remains earthed.

 

I’m sure you are thinking “Yeabut I’m not going to have a short circuit between live and earth” and you are probably right. Probably, but not definitely.

 

I suppose the bottom line is that there’s not much point in earthing your hull if the first time there’s a fault, the earth connection no longer exists. Even though that fault is fairly unlikely.

 

 

 

No I'm certainly not thinking "Yeahbut..." I'm thinking I want the GI to fail short circuit if it fails. However, I'm also wondering what your evidence is for your claim that a Safeshore GI won't fail short circuit if it does fail?

Edited May 7, 2020 by blackrose

[Flyboy]

2 minutes ago, blackrose said:

 

As an owner I posted this to Safeshore and got the following reply:

 

Ratings stated are continuous rating. Pulse ratings are significantly higher. With over 24000 isolators now currently in use we have no reported failures of any isolators. 

How many people actually test their Gi's or even know how to ?  Having no reported failures is a misleading statement because nobody actually knows.

[blackrose]

9 minutes ago, Flyboy said:

How many people actually test their Gi's or even know how to ?  Having no reported failures is a misleading statement because nobody actually knows.

 

Nobody actually knows... Really? Everyone should know how to test their GI. As far as I'm aware every manufacturer includes instructions on how to test them. Safeshore does anyway. It's a fairly simple procedure.

 

If they all failed open circuit at the first fault condition as claimed by nickorman then surely we'd have heard about one case at least?

Edited May 7, 2020 by blackrose

[robtheplod]

I found this which is quite interesting:

 

 

[ditchcrawler]

17 minutes ago, blackrose said:

 

Nobody actually knows... Really? Everyone should know how to test their GI. As far as I'm aware every manufacturer includes instructions on how to test them. Safeshore does anyway. It's a fairly simple procedure.

 

If they all failed open circuit at the first fault condition as claimed by nickorman then surely we'd have heard about one case at least?

What percentage of boaters even check their CO and Smoke detectors. Some boaters have no idea about how anything on a boat works, the turn the key and off they go, if something doesnt work they get someone to fix it.

[nicknorman]

24 minutes ago, blackrose said:

 

No I'm certainly not thinking "Yeahbut..." I'm thinking I want the GI to fail short circuit if it fails. However, I'm also wondering what your evidence is for your claim that a Safeshore GI won't fail short circuit if it does fail?

Guaranteeing to fail short circuit is one of the primary challenges to meet the ABYC standard. I would have thought that if Safeshore devices met that element of the standard, the rest would be pretty easy to comply with and so they would state that it does comply in their advertising blurb.

19 minutes ago, blackrose said:

 

Nobody actually knows... Really? Everyone should know how to test their GI. As far as I'm aware every manufacturer includes instructions on how to test them. Safeshore does anyway. It's a fairly simple procedure.

 

If they all failed open circuit at the first fault condition as claimed by nickorman then surely we'd have heard about one case at least?

I recall someone, pretty sure it was mr Voltmaster (Keith M) of this parish, saying (as a means to dis GIs) that he had attended many boats where he had tested the GI and found it open circuit. If it wasn’t him then it was someone of similar experience.

[blackrose]

1 hour ago, ditchcrawler said:

What percentage of boaters even check their CO and Smoke detectors. Some boaters have no idea about how anything on a boat works, the turn the key and off they go, if something doesnt work they get someone to fix it.

 

Yes I know but some boaters do check their batteries, smoke alarms, CO detectors and their GIs. I've no idea what percentage do those checks but my point still stands that out of 24,000 units we would at heat have heard about one single failure if it had happened.

[blackrose]

1 hour ago, nicknorman said:

Guaranteeing to fail short circuit is one of the primary challenges to meet the ABYC standard. I would have thought that if Safeshore devices met that element of the standard, the rest would be pretty easy to comply with and so they would state that it does comply in their advertising blurb.

 

I recall someone, pretty sure it was mr Voltmaster (Keith M) of this parish, saying (as a means to dis GIs) that he had attended many boats where he had tested the GI and found it open circuit. If it wasn’t him then it was someone of similar experience.

 

Yes I understand that failing short circuit is part of the ABYC standard, but I doubt it's the whole thing. There could be many reasons why Safeshore GIs don't comply, or it could simply be that the admin and costs of compliance are prohibitive? I really don't know but I don't think you know either so your claim that they will all fail at the first fault is spurious. 

 

You were specifically talking about Safeshore GIs previously. Who was the manufacturer of the GIs tested by Keith M that failed?

Edited May 7, 2020 by blackrose

[nicknorman]

33 minutes ago, blackrose said:

 

Yes I know but some boaters do check their batteries, smoke alarms, CO detectors and their GIs. I've no idea what percentage do those checks but my point still stands that out of 24,000 units we would at heat have heard about one single failure if it had happened.

But we have heard about failures. If you mean Safeshore are saying they have never heard of a failure, well they would say that. I have a VW group car and the forum is full of reports of folk taking their car to the dealer with a fairly standard fault, only to be told “we’ve never heard of that fault before”.

 

Anyway, you are in charge of your own risk averseness. I am not trying to tell you to get a better GI that is compliant with an international stardard, it is your choice. But for me, given the choice of 2 GIs at similar price points, one ABYC compliant and one not, it would seem perverse not to get the one compliant with the international standard.

[Chewbacka]

4 minutes ago, nicknorman said:

But we have heard about failures. If you mean Safeshore are saying they have never heard of a failure, well they would say that. I have a VW group car and the forum is full of reports of folk taking their car to the dealer with a fairly standard fault, only to be told “we’ve never heard of that fault before”.

 

Anyway, you are in charge of your own risk averseness. I am not trying to tell you to get a better GI that is compliant with an international stardard, it is your choice. But for me, given the choice of 2 GIs at similar price points, one ABYC compliant and one not, it would seem perverse not to get the one compliant with the international standard.

I have had a GI for 10 years and (touch wood) have never had a fault that caused an over current fault to earth, which is probably not that uncommon, so it’s not surprising that few if any fail. 

[ditchcrawler]

1 minute ago, Chewbacka said:

I have had a GI for 10 years and (touch wood) have never had a fault that caused an over current fault to earth, which is probably not that uncommon, so it’s not surprising that few if any fail. 

There are two threads at the moment live on here at the moment with water in immersion heaters which probably caused an earth fault but with a leak via water unlikely to generate a high earth fault current, unlike when the elements rot through

[Chewbacka]

1 minute ago, ditchcrawler said:

There are two threads at the moment live on here at the moment with water in immersion heaters which probably caused an earth fault but with a leak via water unlikely to generate a high earth fault current, unlike when the elements rot through

But the frequent tripping of the rcd will result in the immersion being fixed long before the earth fault current is high enough to exceed the gi peak rating.

[ditchcrawler]

9 minutes ago, Chewbacka said:

But the frequent tripping of the rcd will result in the immersion being fixed long before the earth fault current is high enough to exceed the gi peak rating.

Maybe

The next one could be a live earth short. Have you seen the state of the two on here before people have asked advice, let alone changed them.

35 minutes ago, nicknorman said:

But we have heard about failures. If you mean Safeshore are saying they have never heard of a failure, well they would say that. I have a VW group car and the forum is full of reports of folk taking their car to the dealer with a fairly standard fault, only to be told “we’ve never heard of that fault before”.

 

Anyway, you are in charge of your own risk averseness. I am not trying to tell you to get a better GI that is compliant with an international stardard, it is your choice. But for me, given the choice of 2 GIs at similar price points, one ABYC compliant and one not, it would seem perverse not to get the one compliant with the international standard.

On a new boat would a GI need to be ABYC compliant to comply with the Recreational Craft Directive. If not what standard would it need to be.? 

[nicknorman]

18 minutes ago, ditchcrawler said:

On a new boat would a GI need to be ABYC compliant to comply with the Recreational Craft Directive. If not what standard would it need to be.? 

The Recreational craft directive is of course a European thing, the ABYC and American thing, so the former doesn’t specifically reference the latter. However the RCD does have this statement, which I think is part of the ABYC requirement (the 5000A bit):

 

A galvanic isolator or other suitable device may be fitted in the protective conductor to resist imported stray galvanic current flow while permitting the passage of a.c. current, if present. Galvanic isolators shall be designed to withstand the application of power from a short-circuit test from a source capable of delivering 5 000 A r.m.s. symmetrically to its output test terminals for the time required for the circuit-breaker in the test circuit to trip. After three applications of the short-circuit test, the electrical and mechanical characteristics of the isolator shall be unchanged.

 

So a Safeshore isolator, which doesn’t mention the 5000A test (and Safeshore seem to have no idea what a realistic transient is) isn’t compliant.

[blackrose]

On 07/05/2020 at 21:37, nicknorman said:

But we have heard about failures. If you mean Safeshore are saying they have never heard of a failure, well they would say that. I have a VW group car and the forum is full of reports of folk taking their car to the dealer with a fairly standard fault, only to be told “we’ve never heard of that fault before”.

 

Anyway, you are in charge of your own risk averseness. I am not trying to tell you to get a better GI that is compliant with an international stardard, it is your choice. But for me, given the choice of 2 GIs at similar price points, one ABYC compliant and one not, it would seem perverse not to get the one compliant with the international standard.

 

One reason I might not want the Aquafax ABYC compliant isolator is because it goes into conduction at only 1.1v, potentially meaning RFI currents activate the diodes and rendering it useless in terms of isolation. But your point is taken, perhaps after nearly 15 years it's time to get a new one, however it's quite difficult to get one with all the features I'd want: ABYC compliance, bypass capacitor for high AC leakage faults, and some sort of status monitor. I don't think the Aquafax one has a bypass capacitor does it? Who actually makes the Aquafax one anyway? It's not clear to me from their website but maybe you need an account to see the full product specs.

 

https://www.aquafax.co.uk/products/galvanic-current-isolator-16a-with-indicator-8-40990#

 

If I get a new GI it might be the Sterling Pro Save C. The only trouble is that although it says it's the same as the Pro Save A with the addition of a bypass capacitor, I can't see whether it incorporates a status monitor like the Pro Save A?

 

https://sterling-power.com/products/zinc-savers-galvanic-isolators

 

Edited May 9, 2020 by blackrose

[blackrose]

On 07/05/2020 at 22:35, nicknorman said:

The Recreational craft directive is of course a European thing, the ABYC and American thing, so the former doesn’t specifically reference the latter. However the RCD does have this statement, which I think is part of the ABYC requirement (the 5000A bit):

 

A galvanic isolator or other suitable device may be fitted in the protective conductor to resist imported stray galvanic current flow while permitting the passage of a.c. current, if present. Galvanic isolators shall be designed to withstand the application of power from a short-circuit test from a source capable of delivering 5 000 A r.m.s. symmetrically to its output test terminals for the time required for the circuit-breaker in the test circuit to trip. After three applications of the short-circuit test, the electrical and mechanical characteristics of the isolator shall be unchanged.

 

So a Safeshore isolator, which doesn’t mention the 5000A test (and Safeshore seem to have no idea what a realistic transient is) isn’t compliant.

 

Again, the problem I have with some of your posts is that you make a lot of assumptions and alarmist claims based on what you can see on the Safeshore website. How do you know they have no idea what a realistic transient is? Have you corresponded with them or is it just because you can't see it on their website? It's not on the Aquafax or Sterling websites either! Yes, they both sell ABYC complaint products but neither are giving full product specs on their websites. I just think you're on very dodgy ground when you slag off companies and products that you don't really know enough about.

Edited May 9, 2020 by blackrose

[Tony Brooks]

51 minutes ago, blackrose said:

 

Again, the problem I have with some of your posts is that you make a lot of assumptions and alarmist claims based on what you can see on the Safeshore website. How do you know they have no idea what a realistic transient is? Have you corresponded with them or is it just because you can't see it on their website? It's not on the Aquafax or Sterling websites either! Yes, they both sell ABYC complaint products but neither are giving full product specs on their websites. I just think you're on very dodgy ground when you slag off companies and products that you don't really know enough about.

 

Except that particular company was telling all and sundry in their adverts that their boat would be eaten away if they did not fit a GI and it took my complaint to the ASA to get it altered to make stop it including 12/24V DC boats. If they wanted to and understood why its important they could put sufficient technical data on their website and adverts but for some reason they don't. I am with Nick on this, for safety we should treat that company's products as suspect under fault conditions.

[WotEver]

2 hours ago, blackrose said:

How do you know they have no idea what a realistic transient is?

See post 60. From Safeshore’s website:

Usually UK marina supplies are either 16 or 32 amps so the isolator must be able safely handle at least 20% more than the maximum current available to comply with legislation. 

 

That is complete nonsense. What ‘legislation’ are they referring to?  If they think a realistic transient is 20% above the rated supply then they’re miles out. If their GIs can handle 5000A transients then why on earth don’t they say so? It’s a good selling point, surely?

[nicknorman]

3 hours ago, blackrose said:

 

Again, the problem I have with some of your posts is that you make a lot of assumptions and alarmist claims based on what you can see on the Safeshore website. How do you know they have no idea what a realistic transient is? Have you corresponded with them or is it just because you can't see it on their website? It's not on the Aquafax or Sterling websites either! Yes, they both sell ABYC complaint products but neither are giving full product specs on their websites. I just think you're on very dodgy ground when you slag off companies and products that you don't really know enough about.

You are to some extent correct in that I am extrapolating from what they say in their website, to the detail of the product. But there is nothing else to go on. If a product is ABYC compliant there is no need to quote the max transient capability (and anyway it’s normally a time integral, because the duration and maximum value of the tolerated fault current are inter-related). Where ABYC compliance is not mentioned and where the advertising blurb talks about a 20% over load condition, the balance of evidence strongly suggests that the device isn’t able to withstand the reasonably expected magnitude of fault current ie around 5000A. If it was compliant they would be stupid not to mention it.

 

If I now contacted them by email and they claimed compliance, I would be inclined not to believe them or at least would want to see exactly how they had tested it. It is fairly easy to get away with lying to an individual customer privately, it is much harder to lie publicly on a website and get away with it, due to the greater exposure and legislation.

 

But I refute your accusation of “alarmist”. I have several times said that the chances of a live to earth dead short happening are pretty remote and much remoter still that such an event would eventually lead to a serious accident or death. My point is only that, given a choice between an ABYC compliant device and one that is not, at similar price points, it would be perverse to go for the one that wasn’t compliant.

Edited May 9, 2020 by nicknorman

[blackrose]

On 09/05/2020 at 13:47, WotEver said:

See post 60. From Safeshore’s website:

 

 

 

That is complete nonsense. What ‘legislation’ are they referring to?  If they think a realistic transient is 20% above the rated supply then they’re miles out. If their GIs can handle 5000A transients then why on earth don’t they say so? It’s a good selling point, surely?

 

But how do you know the 20% they are talking about is peak transients? It might just be an additional 20% rating. I think you and Safeshore might be talking about two different things. Also I haven't seen any mention of 5000A transients on the webpage for the GI you have on the Aquafax website. It may be published somewhere else but I can't see it anywhere.

[blackrose]

On 09/05/2020 at 14:33, nicknorman said:

 

 

On 09/05/2020 at 14:33, nicknorman said:

You are to some extent correct in that I am extrapolating from what they say in their website, to the detail of the product. But there is nothing else to go on. If a product is ABYC compliant there is no need to quote the max transient capability (and anyway it’s normally a time integral, because the duration and maximum value of the tolerated fault current are inter-related). Where ABYC compliance is not mentioned and where the advertising blurb talks about a 20% over load condition, the balance of evidence strongly suggests that the device isn’t able to withstand the reasonably expected magnitude of fault current ie around 5000A. If it was compliant they would be stupid not to mention it.

 

If I now contacted them by email and they claimed compliance, I would be inclined not to believe them or at least would want to see exactly how they had tested it. It is fairly easy to get away with lying to an individual customer privately, it is much harder to lie publicly on a website and get away with it, due to the greater exposure and legislation.

 

But I refute your accusation of “alarmist”. I have several times said that the chances of a live to earth dead short happening are pretty remote and much remoter still that such an event would eventually lead to a serious accident or death. My point is only that, given a choice between an ABYC compliant device and one that is not, at similar price points, it would be perverse to go for the one that wasn’t compliant.

 

Likewise Aquafax must be stupid not to mention it on their website.

 

Well you can refute being alarmist all you want, but when you state on a public forum (without any evidence whatsoever) that "at the first sign of a short circuit to earth a safeshore GI will disappear in a puff of smoke" , that's definitely being alarmist. 

 

I do take your last point and as I said previously, after all this time it's probably time for me to buy a new GI anyway. It looks like the Aquafax model doesn't have any bypass capacitor for high AC leakage faults. Given a choice between the Aquafax unit and the Sterling ABYC compliant GI which are at at similar price points, it would be perverse to go for the one that didn't have the bypass capacitor.

Edited May 10, 2020 by blackrose

[blackrose]

On 09/05/2020 at 12:13, Tony Brooks said:

 

Except that particular company was telling all and sundry in their adverts that their boat would be eaten away if they did not fit a GI and it took my complaint to the ASA to get it altered to make stop it including 12/24V DC boats. If they wanted to and understood why its important they could put sufficient technical data on their website and adverts but for some reason they don't. I am with Nick on this, for safety we should treat that company's products as suspect under fault conditions.

 

I think you're mixing up two different things Tony. Lots of firms selling GIs and ITs talk about metal parts being eaten away without isolation of some sort. I can't really understand what point you're trying to make other than deliberately trying to besmirch a particular company's products. At a guess I'd estimate 90% of GIs on the market aren't ABYC compliant. So can you tell me exactly what makes Safeshore's offerings any more suspect that any of the other non-compliant units?

 

If mine is suspect then I must have been testing it wrong over the last 15 years.

Edited May 10, 2020 by blackrose

[Tony Brooks]

If what you say is correct  then why did the ASA get them to alter their adds? They gave a blanket "all boat" statement that if the boat did not have galvanic isolation (they said galvanic isolator) then the hull would get eaten away - no qualification, no mentioning it did not apply only to boats using a shoreline. That was misleading otherwise the ASA would not have acted.

 

I can only presume you have some kind of relationship with that company because of the way you seem to try to defend the indefensible.

[blackrose]

21 minutes ago, Tony Brooks said:

If what you say is correct  then why did the ASA get them to alter their adds? They gave a blanket "all boat" statement that if the boat did not have galvanic isolation (they said galvanic isolator) then the hull would get eaten away - no qualification, no mentioning it did not apply only to boats using a shoreline. That was misleading otherwise the ASA would not have acted.

 

I can only presume you have some kind of relationship with that company because of the way you seem to try to defend the indefensible.

 

I don't know anything about the ASA case you're talking about other than what you've been saying on this thread. However, if what you say is true then I assume the ASA got Safeshore to change their ads because they're the ads that you complained about! ? My point is why have you not made complaints to the ASA about all the similar ads from other companies that basically say the same thing? Just look at any ads for GIs - they all talk about various degrees of possibility of metal parts and boats being eaten away. So why did you choose Safeshore in particular to complain about?

 

My only relationship with Safeshore is as a satisfied customer over the last 15 years. I think you're fully aware that most boaters on this forum defend their own choice of equipment to some degree when it comes under attack (toilets, bow thrusters, engines, electrical equipment, etc). This is no different. Your accusation that I have some other sort of relationship with Safeshore is incorrect and a particularly clumsy attempt to discredit me personally. As such it has been reported.

Edited May 10, 2020 by blackrose