Installing mains electric

[Keith M]

Not entirely true, as some galvanic isolators come with a gauge.

 

How can the gauge tell when it has failed

 

My understanding is that the gauge shows you when it is passing voltage to earth

 

keith

[twelveeyedfish]

Well those aren't that expensive really. I'm not sure what the hoo har is about! I was expecting a much bigger price differential compared to the galvanic isolator.

 

It's not trivial to install these then? the shoreline must come in, go to the box and then come out all in total isolation from the hull. To me the shoreline connector is the weak link here! You can't just leave this on the back of the boat or on the bank really can you.

[Keith M]

Smileypete, thanks.

 

I have made systems to be installed on gas and oil rigs and ferrules are a requirement in these places. Is it required on a narrow boat or just desirable?

 

Nicknorman: Surely a shorted diode has no voltage across it as it's a short? It's when they fail open circuit which is the problem.

Varistors tend to fail OC which is why TVS diodes are preferred these days.

 

 

Yes it is a requirement

 

As lay out in ISO 10133

 

And the wording is along the lines of all wires being fitted into a screw terminal must have some type of terminal fitted

 

Keith

[jonathanA]

 

 

Yes it is a requirement

 

As lay out in ISO 10133

 

And the wording is along the lines of all wires being fitted into a screw terminal must have some type of terminal fitted

 

Keith

 

would you care to quote the BSS item that refers to this being 'required'

 

Ta

[nicknorman]

Yes it is a requirement

 

As lay out in ISO 10133

 

And the wording is along the lines of all wires being fitted into a screw terminal must have some type of terminal fitted

 

Keith

When is it required to comply with ISO 10133? I'm guessing its swept up in the RCD but that only applies to new builds, does it not? It's certainly not a required part of the BSS.

[frangar]

With regard to the use of ferrules whilst I use them wherever possible on both AC & DC there is some equipment where due to design of housings etc you can't physically fit them.....I think in such instances it's best to judge the risk....is it better to have strain on the terminal block or cable or run the risk of cable strands being cut??.....I tend to go for cable strands being cut and make sure I have twisted ( but NOT tinned) the ends of the cable.

 

Cheers

 

Gareth

[Keith M]

When is it required to comply with ISO 10133? I'm guessing its swept up in the RCD but that only applies to new builds, does it not? It's certainly not a required part of the BSS.

 

Yes it is part of the RCD

 

So surely any work undertaken should still comply with the RCD for at least the first four years.

 

I would also like to thing the an ISO carries a lot more weight than a BSS examination which was put together by BWB.

 

Keith

 

would you care to quote the BSS item that refers to this being 'required'

 

Ta

 

Was your boat constructed to the RCD than the electrical installation should have complied with ISO 10133 and 13297

 

Keith

There are two types of of Blue Arctic cable

 

One is made to BS 6500 this is a light duty cable for intermittent use.

 

The other is BS 7919 for continues use

 

Keith

[frangar]

There are two types of of Blue Arctic cable

 

One is made to BS 6500 this is a light duty cable for intermittent use.

 

The other is BS 7919 for continues use

 

Keith

I'm not sure that's quite true Keith......and it's more to do with the resistance of the sheathing to oil/wear etc than electrical loading.....BS 6500 is for " normal" flex......BS7919 covers artic and H07

 

Having said that I'm not quite sure why artic cable is used on boats......it's main attribute is the sheathing is flexible at low temperatures...which if it's correctly clipped etc won't be an issue.....

 

Given all that I would still use either artic or H07 spec cable on a boat as it's the easiest way of getting double insulation with the right cross section of copper.

 

Cheers

 

Gareth

Edited October 16, 2013 by frangar

[nicknorman]

Yes it is part of the RCD

 

So surely any work undertaken should still comply with the RCD for at least the first four years.

 

I would also like to thing the an ISO carries a lot more weight than a BSS examination which was put together by BWB.

 

Keith

 

 

We've mentioned ISO 10133 but of course, the thread title is about mains wiring so its ISO 13297. Anyway, I don't think 4 years is mentioned in the RCD as a time during which compliance with the directive, post- manufacture, is required. Yes it's regarded as a BSC alternative, but a bit like an MOT, both the BSC and the CE marking only mean that the boat was compliant at the time of issue.

 

Don't forget, I am not arguing about what is good practice, I am arguing about whether use of ferrules for multistrand wiring is required by law when modifying a boat.

[smileypete]

With regard to the use of ferrules whilst I use them wherever possible on both AC & DC there is some equipment where due to design of housings etc you can't physically fit them....

 

Just curious, what sort of equipment is that? There are uninsulated bootlace ferrules which should be more compact than the usual ones:

 

http://cpc.farnell.com/pro-power/sten-2508/ferrules-uninsulated-bootlace-2/dp/CN11652

 

There's also red/blue/yellow pin crimps and thin blade crimps for use with a standard ratchet crimper, but they increase the depth needed in back boxes so aren't ideal.

 

cheers, Pete.

~smpt~

[twelveeyedfish]

I have all the above types of ferrals in my toolkit

 

So this is the electronic engineer in me speaking now : What could possibly cause a galvanic isolator to fail? Four diodes back to back is just safer than a safe thing. You should only ever need to test them if your shoreline fuse has tripped really. And that's not hard.

 

I get the impression I could make one of these for a fiver.

[nicknorman]

What causes a GI to fail is a short circuit from live to earth. This results in a huge current flowing through the GI diodes until the breaker blows, which of course takes a finite amount of time. Short duration, but as you will know its about the heat transference from the semiconducting die to the case etc which has more thermal mass. Thus the diode can fail internally without any external signs of distress.

 

Yes I would agree that you really only need to test them if you have had a breaker trip.

 

There have been a few threads on home-made GIs but the consensus was that the massive peak current and current integral requirement (at least 5000A IIRC ) makes it expensive to source the parts for a one-off and its cheaper to buy a ready made unit.

[twelveeyedfish]

Hmm Nicknorman, I make things that do more horrible stuff than that on a daily basis.

 

others: I just popped into our old friends Block and Quaile and saw this Blue Arctic cable stuff and it only has BS6500 on it. I haven't looked at what either standards cover yet but I I can't pretend I'm not confused. Something for the weekend I think!

[nicknorman]

The thread I was thinking of is here if you are interested:

http://www.canalworld.net/forums/index.php?showtopic=38125

[Keith M]

We've mentioned ISO 10133 but of course, the thread title is about mains wiring so its ISO 13297. Anyway, I don't think 4 years is mentioned in the RCD as a time during which compliance with the directive, post- manufacture, is required. Yes it's regarded as a BSC alternative, but a bit like an MOT, both the BSC and the CE marking only mean that the boat was compliant at the time of issue.

 

Don't forget, I am not arguing about what is good practice, I am arguing about whether use of ferrules for multistrand wiring is required by law when modifying a boat.

 

If any modification are carried to either the AC or DC wiring during the first four years sure they must comply with the RCD? which is covered by trading standards.

 

I would say that ferrules must be used because both the AC and DC ISO state that ferrules must be used.I feel that these documents will carry more weight than the BSS if challenge by trading standards.

 

Keith

[nicknorman]

Well that is my question really. The RCD applies to new built craft. Once that craft is completed certified and delivered to its owner, as far as I'm aware that's the end of the RCD's involvement. It would not be involved in subsequent modifications made by the owner. If you know different, please quote the relevant bit of legislation.

 

Certainly trading standards would have no interest in what a private owner does with his boat after purchase.

[Paul C]

Perhaps the insurance company would though? If a boat under 4 years old (therefore with no BSS - using the fact that it complies with RCD for its CRT licence conditions to be satisfied etc); and it was subsequently modified by a DIY owner, not to adequate requirements, and subsequently something happened (for example an electrical fire) which resulted in a claim on the insurance. Or a similar scenario but where a boat was <4 yrs old, DIY modified, then sold (with its RCD and no BSS), then a new owner had an incident, trading standards way well be involved.

 

Of course, this assumes a worst-case scenario and also if you think that stepping outside the relevant ISO requirement immediately results in it being "inadequate".

 

On the one hand one may think its just a bunch of useless red tape, on the other hand its there to protect us (and others) from dangerous boats.

 

I'd say for the sake of something as cheap as ferrules, the balance is on fitting them to keep within the requirements.

[twelveeyedfish]

Ferrules are cheap - like all crimps.

 

It's the crimping tool which costs a fortune!

[nicknorman]

 

Perhaps the insurance company would though? If a boat under 4 years old (therefore with no BSS - using the fact that it complies with RCD for its CRT licence conditions to be satisfied etc); and it was subsequently modified by a DIY owner, not to adequate requirements, and subsequently something happened (for example an electrical fire) which resulted in a claim on the insurance. Or a similar scenario but where a boat was <4 yrs old, DIY modified, then sold (with its RCD and no BSS), then a new owner had an incident, trading standards way well be involved.

 

Of course, this assumes a worst-case scenario and also if you think that stepping outside the relevant ISO requirement immediately results in it being "inadequate".

 

On the one hand one may think its just a bunch of useless red tape, on the other hand its there to protect us (and others) from dangerous boats.

 

I'd say for the sake of something as cheap as ferrules, the balance is on fitting them to keep within the requirements.

The old "insurance company" line is getting a bit tired these days. Anyway Im not arguing against using ferrules, merely against the suggestion that its a legal requirement so to do.

[twelveeyedfish]

From my own experience, the use of ferrules is only necessary in explosive atmospheres. Never needed them anywhere else, not even in high voltage or hot environments. Not that this is down to the specs you're interpreting but it's a third angle at least. I have shipped thousands of products without them

[Paul C]

 

 

The old "insurance company" line is getting a bit tired these days. Anyway Im not arguing against using ferrules, merely against the suggestion that its a legal requirement so to do.

 

What do you define as "legal requirement" though - RCD in itself isn't a legal requirement, it only becomes "legal" when the licensing, or the offering of sale, is done. For example if I owned a large area of land with a lake on it (or its own canal), I could build my own boat not conforming to RCD requirements and use it, etc

 

I think in the context/assumption that everyone licences their boat to be on a navigation authorities waters which do require BSS or RCD, then we could reasonably interpret the requirement for valid RCD to be a legal requirement.

 

Modifying a boat after its obtained its BSS or RCD is a different matter - I believe its a byelaw to keep the boat safe (paraphrasing a lot) but its not attached to the licence conditions, however I admit I don't know enough about all the byelaws of all the waterways to be 100% sure!

 

 

One could say that the requirements of your insurance to keep the boat in a seaworthy condition (and all its other terms and conditions, so long as they're reasonable) are indirectly a legal requirement, since if you didn't, and they didn't honour your claim on that basis....you'd be in breach of the (legal) requirements of the licence. Vaguely similar to car insurance where if you have undeclared modifications to your car.

[nicknorman]

Yes but keeping your boat in a seaworthy condition etc is not the same as saying it must comply with the letter of some ISO. I am seeking justification for posts 32 and 40, not arguing against keeping one's boat in a safe conditon nor the use of ferrules. However I don't think Im going to get it!

[jonathanA]

to support nick we can argue about ferrules v crimp v solder and quote standards 'till we are blue in the face - bottom line is that crimps/ferrules/solder on flex is NOT a requirement (legal or otherwise) on non hire use narrow boats nor indeed is the use of Flex.

 

in a court of law /insurance company loss adjuster situation i would point to the BSS and say i met the accepted standards as laid down by the appropriate body. end of

 

RCD/trading standards, Iso, IEE 17th simply don't apply and you are simply wrong to argue they do.

[Keith M]

I feel that any vessel which has been constructed to comply with RCD original must continue to comply during the life of the craft

 

And with out looking up my RCD course notes I think that this is a legal requirement, very happy to be wrong.

 

What legal status does a BSS have none that I am aware of only if you do not have one you do not get a to join the CRT club.

 

The BSS electrical section are some standards which have with no reference to any excepted world wide standards ABYC, ISO 10133 & 13297 and the BMEA C of P

 

Keith

[smileypete]

There have been a few threads on home-made GIs but the consensus was that the massive peak current and current integral requirement (at least 5000A IIRC ) makes it expensive to source the parts for a one-off and its cheaper to buy a ready made unit.

 

Firstly, for a narrowboat with RCD on board and very likely one on the shoreline, I don't think the IT is that much safer than a GI. In fact if the IT is on board which it usually is it's almost certainly less safe than a GI.

 

Anyway.... under surge conditions I expect the internal resistance of the diodes dominates over temperature coefficient effects, so one way to improve the surge rating is just more diodes in parallel. And if you're really paranoid you could add some chunky varistors in parallel too.

 

For a narrowboat I think it's pretty much hair splitting; having a SECOND smoke alarm, CO alarm, and automatic bilge pump, plus better general care in difficult conditions would do way more good.

 

cheers, Pete.

~smpt~