Transformers & Isolators

[nb.Stealaway]

That's ok catweasel, I havn't much experience of armoured cable so don't know either . Will keep my eyes open for a flexible armoured cable suitable for use outside.

[WotEver]

I do know electrical wholesalers sell a flexible cable with armoured covering that is suitable for exterior use.

 

Yep, I've seen flexible armoured used by A/C installers but I've no idea of the current carrying capacity. I guess a call to any electrical wholesaler would soon sort out what's available.

 

Regards,

Tony

 

Even with the transformer on the bank (where I want it, & where I am going to put it) I will have to run the shorelead along the roof the whole length of my boat to the inlet at the stern & therefore would have a live feed on/near/touching the boat without having that feed's earth connected to the hull. This is why I feel for my particular case I need the rcd.

 

Hmmm... I'm not sure I was completely clear about this. If you use a transformer the whole idea is that it is between the shore power and your boat. Therefore if you're saying that the shore power is at the bow and your inlet on the boat is at the stern, the transformer should be on the bank at the bow, with the OUTPUT of the transformer running along the roof. It's important to keep the shore power away from the structure of the boat because there will be no connection from the earth of that feed and the hull.

 

Also, what I meant by 'fail-safe' is that if the shore power should disappear for any reason, even for a second (like a brief power cut) the in-line RCD will (may) switch itself off until it's manually reset.

 

Hope that all makes sense,

Tony

[nb.Stealaway]

Hi agian Tony, I think we have understood each other. Yes, the transfomer will be on the bank about 5ft from the bow. I will keep the shorepower INPUT to the transformer & kept well clear of the hull. The OUTPUT will be fitted with an inline rcd immediately after the transformer & this will then run to & along the boat (as you said).

I also understood about the fail safe thing. I believe it's so powertools etc. don't become live again eg. while you're away resetting the (main) trip, as this could be a hazard. However, as you pointed out, this would probably just be an inconvenience with relation to the boat.

 

I hope I've got this all correct now, I appreciate no-ones trying to be a pedant, just making sure it's wired correctly & SAFELY. That is after all my main concern.

 

Thanks again to all who have helped here,

 

Best regards

[WotEver]

Sounds like you're good to go then

 

Edited to remove superfluous quote.

Edited June 22, 2009 by tony@hdheaven.co.uk

[flatplane8]

I am considering getting an isolation transformer, such as the ir link one linked to recently & have just noticed the seem to do a specific 'isolation transformer for boats' , here , and was wondering if it was worth it or are the just charging an extra 20quid for a yellow case and an earth-neutral bond? I would also like to be able to keep it on the bank due to its size, security shouldn't be an issue on my mooring, I assume this will be ok if wired as per here .

Thanks,

 

Charles

nb. Stealaway

 

 

Hi,

 

I've just got an Airlink transformer, but didn't realise that they now did a specific boat one, so I ordered the 3230, which only has two input and two output wires. I know I need to connect earth and neutral on the boat end, do I simply have no earth connected on the shorepower cable?

 

Thanks,

 

Simon

[GUMPY]

Hi,

 

I've just got an Airlink transformer, but didn't realise that they now did a specific boat one, so I ordered the 3230, which only has two input and two output wires. I know I need to connect earth and neutral on the boat end, do I simply have no earth connected on the shorepower cable?

 

Only two in and out thats rare.

Input

wire live to live terminal

neutral to neutral terminal

and terminate the earth

Output

live to live terminal

neutral and earth to neutral terminal

do not link neutral and earth in the boat do it as above on the output of the transformer

[flatplane8]

Only two in and out thats rare.

Input

wire live to live terminal

neutral to neutral terminal

and terminate the earth

Output

live to live terminal

neutral and earth to neutral terminal

do not link neutral and earth in the boat do it as above on the output of the transformer

 

 

Thanks Julian, hoped you'd reply. Thats how I had figured it would be based on articles that I'd read, but wasn't 100% sure.

Edited August 19, 2009 by flatplane8

[Gibbo]

BUT...............

 

The chassis of the transformer ABSOLUTLEY MUST be connected to the incoming shorepower earth.

 

Gibbo

[flatplane8]

BUT...............

 

The chassis of the transformer ABSOLUTLEY MUST be connected to the incoming shorepower earth.

 

Gibbo

 

 

Not possible in this case, as its one of Airlink's 'potted' transformers, hence my question.

[Gibbo]

Not possible in this case, as its one of Airlink's 'potted' transformers, hence my question.

 

Then it shouldn't be used on a boat.

 

Is it certfied as being double insulated?

 

Gibbo

[flatplane8]

Then it shouldn't be used on a boat.

 

Is it certfied as being double insulated?

 

Gibbo

 

To IP67 (if thats what you mean). I know that others have used them on boats, but as I say, they now do one with a connection for the input earth to the transformer electrostatic screen.

[RLWP]

To IP67 (if thats what you mean). I know that others have used them on boats, but as I say, they now do one with a connection for the input earth to the transformer electrostatic screen.

 

IP67 means it protected against ingress of dust and water between 15cm and 1m. It's not an electrical spec

 

link

 

Richard

[flatplane8]

Actually, I should've done a bit more research. Looks like both the Airlink transformers mentioned are fine.

From Airlink's website, diagram at the bottom of the page.

[Gibbo]

Actually, I should've done a bit more research. Looks like both the Airlink transformers mentioned are fine.

From Airlink's website, diagram at the bottom of the page.

 

Ok that's fine.

 

It's that earth in the diagram on the left connecting the shorepower earth to the transformer chassis. It's absolutely critical to the safety of the installation unless the transformer is double insulated.

 

PS. That's assuming you do actually mean the very bottom diagram. The other (despite what they say) should not be used on a boat. It doesn't mention double insulation so no earth is an absolute no no.

 

Gibbo

Edited August 19, 2009 by Gibbo

[GUMPY]

Ok that's fine.

 

It's that earth in the diagram on the left connecting the shorepower earth to the transformer chassis. It's absolutely critical to the safety of the installation unless the transformer is double insulated.

 

PS. That's assuming you do actually mean the very bottom diagram. The other (despite what they say) should not be used on a boat. It doesn't mention double insulation so no earth is an absolute no no.

 

Gibbo

 

The first potted ones they made had a ceramic screen (This is what they said) which removes the need for the ground connection to the primary.

 

Mine is in a metal box in the shed and unpotted!

[Gibbo]

The first potted ones they made had a ceramic screen (This is what they said) which removes the need for the ground connection to the primary.

 

That's probably ok then as long as the rest of it is built double insulated.

 

Mine is in a metal box in the shed and unpotted!

 

Mine is in Liverpool Bay as it fell off the bows.

 

Gibbo

[flatplane8]

Thanks for the advice, mine is the one without the earth connection to the screen, but it looks like this transformer is ok in this configuration.

[WotEver]

Thanks for the advice, mine is the one without the earth connection to the screen, but it looks like this transformer is ok in this configuration.

 

I'm confused. Do you mean yours is as per the first of the two diagrams on this page? http://www.airlinktransformers.com/technic...ting.asp?data=2

 

If so, then as Gibbo has already pointed out it is NOT suitable for use on a boat. It must be as per the second (bottom) diagram.

 

I worry about a company that writes "load amperage" in a technical document...

 

T

[GUMPY]

I'm confused. Do you mean yours is as per the first of the two diagrams on this page? http://www.airlinktransformers.com/technic...ting.asp?data=2

 

If so, then as Gibbo has already pointed out it is NOT suitable for use on a boat. It must be as per the second (bottom) diagram.

 

Not if it has a ceramic screen as some of them do.............and is therefore OK see previous posts.

[WotEver]

Not if it has a ceramic screen as some of them do...

 

So it's definitely double insulated?

[GUMPY]

So it's definitely double insulated?

I haven't destroyed one to find out and its not marked with the double square

but Airlink have said it has a ceramic screen and it has a plastic case with the transformer encased in resin inside that.

I think that you may be looking for a problem when none exists.

If so kindly show me the regulation that says that this type of transformer is unsuitable for the use its being put to.

By regulation I mean a specific paragraph from BS7671:2008 or similar publication, not some here say off the interweb.

[Gibbo]

It's in IEC 61140 but I can't remember where and I don't have one handy.

 

Gibbo

 

PS. If it doesn't have an earth then it has to be certified as being class II. The standard is very clear on that point.

Edited August 21, 2009 by Gibbo

[WotEver]

Airlink have said it has a ceramic screen and it has a plastic case with the transformer encased in resin inside that.

 

In that case it's double insulated (double squares or not) and you're good to go.

 

kindly show me the regulation that says that this type of transformer is unsuitable for the use its being put to.

By regulation I mean a specific paragraph from BS7671:2008 or similar publication, not some here say off the interweb.

 

I don't need regulations nor hearsay to know when something's dangerous. I've never read a regulation that says I shouldn't drop a live wire into the cut, but I don't think I'll be trying it any time soon.

 

You've said it doesn't have a steel screen and that it's encased in resin, so it's double insulated and will be just fine.

 

(I still worry about a company that writes "load amperage" in a technical document though...)

 

T

 

Edit to say that I've just seen Gibbo's post (posted the same time as me) and my comment that it doesn't need the double squares is therefore wrong - it must be certified/marked.

Edited August 21, 2009 by WotEver

[WotEver]

It's in IEC 61140 but I can't remember where and I don't have one handy.

 

7.3.1, 7.3.2, 7.3.3

 

T

[GUMPY]

Edit to say that I've just seen Gibbo's post (posted the same time as me) and my comment that it doesn't need the double squares is therefore wrong - it must be certified/marked.

 

Being really picky only if it is a finished consumer item, which it is not, as you have to wire it yourself!