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Hi,


We are planning to upgrade from galvanic isolator to galvanic transformer. Our boat is currently on 32 Amp. I found this transformer and nearly went ahead and bought it, however, I’m not sure it meets the wattage requirements. (32 x 230 = 7360w), this transformer falls short. Any advice or recommendations of different transformers appreciated.

 

https://www.batterymegastore.co.uk/product/victron-energy-isolation-transformer-7000w-230v

 

Thanks

Jo 

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15 minutes ago, Jo Green said:

Hi,


We are planning to upgrade from galvanic isolator to galvanic transformer. Our boat is currently on 32 Amp. I found this transformer and nearly went ahead and bought it, however, I’m not sure it meets the wattage requirements. (32 x 230 = 7360w), this transformer falls short. Any advice or recommendations of different transformers appreciated.

 

https://www.batterymegastore.co.uk/product/victron-energy-isolation-transformer-7000w-230v

 

Thanks

Jo 

Others will come along soon but all are going to say something like 'how is your boat set up in electrical terms' That your supply is on 32a cover is a little bit of a red herring. 

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I bet you won't find a 32 Amp shore power supply, more like 16 amps if you are exceptionally lucky an could only be 6 amps in some places.

 

Be aware that I think it it was Victron (others may confirm) who wired their incorrectly, but they probably sorted some time ago.

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2 minutes ago, Tony Brooks said:

Be aware that I think it it was Victron (others may confirm) who wired their incorrectly, but they probably sorted some time ago.

AFAIK it's still the same 🌚

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A 'large' isolation transformer is hardly ever fitted to a narrowboat because of their cost and bulk.

I suggest what you need (if you don't already have one) is a galvanic isolator - which protects the steel hull from corrosion and these are much less expensive.

If you are concerned about electric shock or breakdown, then a good quality domestic fuseboard is usually sufficient - especially if you fit the latest all-singing-and-dancing type of circuit breakers.

 

Folks here are casting derision on a 32 Amp power supply - my marina has them on the power bollards - but most boaters seem to be happy with a 16 amp supply. Don't confuse the socket rating with the total demand for power on your boat which is 2-3 Kw maximum.

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Just now, OldGoat said:

A 'large' isolation transformer is hardly ever fitted to a narrowboat because of their cost and bulk.

I suggest what you need (if you don't already have one) is a galvanic isolator - which protects the steel hull from corrosion and these are much less expensive.

If you are concerned about electric shock or breakdown, then a good quality domestic fuseboard is usually sufficient - especially if you fit the latest all-singing-and-dancing type of circuit breakers.

 

Folks here are casting derision on a 32 Amp power supply - my marina has them on the power bollards - but most boaters seem to be happy with a 16 amp supply. Don't confuse the socket rating with the total demand for power on your boat which is 2-3 Kw maximum.

They already have an isolator and look like they wish ti upgrade to a transformer.

 

Of course the pros and cons of each have been well thrashed out on here but for me if you can afford it a transformer is better, accepting even they are not 100% perfect in every scenario. 

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26 minutes ago, Tracy D'arth said:

You must have a shore lead like a liner mooring rope if you are sucking 32 Amps.

What are you doing? Charging a car on the boat? Or is it an electric boat?

Seeing he seems to give his boat locations as Hurley (on Thames) i would suggest that his marina is equipped for charging electric boats and also supplying large floating flats with a high electrical demand. I doubt many canal marinas have 32 amp supplies to the bollards

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1 hour ago, Tony Brooks said:

I bet you won't find a 32 Amp shore power supply, more like 16 amps if you are exceptionally lucky an could only be 6 amps in some places.

 

Be aware that I think it it was Victron (others may confirm) who wired their incorrectly, but they probably sorted some time ago.

Quite a few marinas that offer residential berths have a full 32a supply on some bollards.

 

Sawley Marina & Kings Marina for example

 

 

Edited by Alan de Enfield
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1 minute ago, Alan de Enfield said:

Quite a few marinas that offer residential berths have a full 32a supply.

 

Sawley Marina & Kings Marina for example

 

 

It's not compulsory to draw it though Alan nor, I expect, would many 'normally' equipped cruising narrowboats ever need to. Of course, the OP is in London, so we may not be talking a normally equipped cruising narrowboat, but the point is the same - its the potential draw of the fitted systems that's important in the rating of this transformer, not the capacity of the shore supply or the maximum rating of the Shore Supply connection point that has been installed in the boat.  We don't yet have that info from the OP.  She may have nothing bigger than a 240v telly to power or she could have an all electric kitchen with an induction hob and a 3kw domestic immersion heater.

 

More info required methinks.

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5 minutes ago, Sea Dog said:

It's not compulsory to draw it though Alan nor, I expect, would many 'normally' equipped cruising narrowboats ever need to.

 

Indeed, but I was answering the statement :

 

I bet you won't find a 32 Amp shore power supply, more like 16 amps if you are exceptionally lucky an could only be 6 amps in some places.

 

Yes - agreed that a cruising boat is unlikely to need a 32a supply otherwise they would struggle when cruising and supplying that demand from batteries.

 

Yes - agreed just because you have it available does not mean that you will use it, but it's there if ever you do need it. A bit like these cruising boats with a 3KV inverter, how often do they need that, and how long can the batteries support a 300 amp draw ?

 

Remember this is (probably) a liveaboard in London with a 7Kw electric shower.

Edited by Alan de Enfield
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Just now, Alan de Enfield said:

 

Indeed, but I was answering the satement that canal marinas were unlikely to offer the facility.

 

I recognise that Alan, and know that you understand both the science and the issue here - the London thing may well be key.

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Just now, Sea Dog said:

I recognise that Alan, and know that you understand both the science and the issue here - the London thing may well be key.

It may be, but Residential moorings with 32a shoreline bollards are available in 'non-London' marinas.

 

If someone posted saying I have a 32 amp supply in my Marina in Derbyshire, or Nottinghamshire, would we say 'that could be the key' ?

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1 minute ago, Alan de Enfield said:

It may be, but Residential moorings with 32a shoreline bollards are available in 'non-London' marinas.

 

If someone posted saying I have a 32 amp supply in my Marina in Derbyshire, or Nottinghamshire, would we say 'that could be the key' ?

I agree - I'm just saying we don't yet know if the 32a is a red herring.  The average canal boat is probably not going to be needing more than a 16a supply even if it has a 32a rated shore connection fitted (as mine does actually), but there are some around built as if an unlimited supply of electrical power is available, even on the cut.  I think, however, that the London location makes it more likely that this could be the case here, but we won't know hence can only speculate as to whether the proposed 7KVA transformer will be meaty enough until we have more detail from the OP.

  • Happy 1
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48 minutes ago, Alan de Enfield said:

Quite a few marinas that offer residential berths have a full 32a supply on some bollards.

 

Sawley Marina & Kings Marina for example

 

 

Priory Marina at Bedford, also a BWML marina.

 

Still have the adaptor I made up. 

 

But why have some CRT bollards on VMa have 63 amp sockets?

Edited by pearley
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2 hours ago, Jo Green said:

Hi,


We are planning to upgrade from galvanic isolator to galvanic transformer. Our boat is currently on 32 Amp. I found this transformer and nearly went ahead and bought it, however, I’m not sure it meets the wattage requirements. (32 x 230 = 7360w), this transformer falls short. Any advice or recommendations of different transformers appreciated.

 

https://www.batterymegastore.co.uk/product/victron-energy-isolation-transformer-7000w-230v

 

Thanks

Jo 

Yep it's a 32amp IT and will do the job if you require a 32amp IT.   Note it's around about 90%+ efficient, so you won't get the full 32amp from the supply.

Edited by Robbo
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On 01/01/2021 at 15:22, Tony Brooks said:

Be aware that I think it it was Victron (others may confirm) who wired their incorrectly, but they probably sorted some time ago.

I have one of these 7KW Victron IT's on Consort. Wasn't aware of incorrect wiring. Can anyone tell me what it was and is there a mod for correcting it?

Ta

Stephen

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1 minute ago, Stephen Jeavons said:

I have one of these 7KW Victron IT's on Consort. Wasn't aware of incorrect wiring. Can anyone tell me what it was and is there a mod for correcting it?

Ta

Stephen

I find it hard to believe Victorn could make a fundamental cock-up  but more than one person who's views I respect has said so. I think its to do with where the screen earth is connected. I think they have it on the boat side rather than the company side so a short to screen might make your hull live. Note the "I think", I would rather others who really know the subject comment.

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Simple answer is not easily.

I am not sure if the 7kva one is wired the same as the 3.6kva which is where the problem was noticed.

The problem with the wiring is that the earth for the casing and transformer core is taken to the boat earth and not to the incoming earth as it should be.

If the transformer fails for any reason and the core becomes live you could then have a live boat as the RCBO on the primary side may not trip.

If you change it you are then left with a metal box that is connected to shore earth and would need to be enclosed in an insulated box.

 

I will add that the chance of this happening is very low but was enough to make me buy elsewhere.

It's an old problem but I don't think Victron ever did anything about it.

Edited by Loddon
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On 07/01/2021 at 16:43, Loddon said:

Simple answer is not easily.

I am not sure if the 7kva one is wired the same as the 3.6kva which is where the problem was noticed.

The problem with the wiring is that the earth for the casing and transformer core is taken to the boat earth and not to the incoming earth as it should be.

If the transformer fails for any reason and the core becomes live you could then have a live boat as the RCBO on the primary side may not trip.

If you change it you are then left with a metal box that is connected to shore earth and would need to be enclosed in an insulated box.

 

I will add that the chance of this happening is very low but was enough to make me buy elsewhere.

It's an old problem but I don't think Victron ever did anything about it.

The above statement is true however in this case the shore RCBO would certainly trip in the event of a fault to earth as it would unbalance the RCD part of the breaker. In this case the casing of the IT would be live for about 30-40mS.

Of course the state of shore electrics is a question mark for most marinas. I installed and tested all my own shore electrics and routinely test the RCBO so I feel confident it should trip with such a fault.

 

I'd still like to get an answer from Victron about whether the 7KW IT has the same fault and will be writing to them.

Incidentally, what product did you buy and how does it resolve this issue?

Stephen

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On 01/01/2021 at 15:22, Tony Brooks said:

I bet you won't find a 32 Amp shore power supply, more like 16 amps if you are exceptionally lucky an could only be 6 amps in some places.

 

Be aware that I think it it was Victron (others may confirm) who wired their incorrectly, but they probably sorted some time ago.

There are now many marina within the UK supplying 32 amps. Because craft are being used as floating offices, I have installed and commissioned many installation.

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That is not the reason 

6 minutes ago, Stephen Jeavons said:

The above statement is true however in this case the shore RCBO would certainly trip in the event of a fault to earth as it would unbalance the RCD part of the breaker. In this case the casing of the IT would be live for about 30-40mS.

Of course the state of shore electrics is a question mark for most marinas. I installed and tested all my own shore electrics and routinely test the RCBO so I feel confident it should trip with such a fault.

 

I'd still like to get an answer from Victron about whether the 7KW IT has the same fault and will be writing to them.

Incidentally, what product did you buy and how does it resolve this issue?

Stephen

The reason the metal box is a problem is because it could compromise the grounding of the boat thus rendering the IT ineffective.

To be honest an IT should not even be on the boat but should be next to the supply on the bank as mine was for many years.

I bought an Airlink transformer, possibly the first one they supplied for use on a boat, one of these

https://airlinktransformers.com/product/enclosed-isolating-industrial-transformer-wm3602

This was before they developed the potted version which they did at my suggestion.

Mine was in a metal enclosure that sat next to the supply in the shed at my old mooring.

When I changed moorings 2 years ago some 13 years after it was installed I recased it in an HPDE box and it is now in a cupboard at the back of my boat fed by a double insulated cable enclosed in plastic conduit to try and prevent anything that may compromise the boats grounding. I much prefer a transformer off the boat and I even worry about cables feeding into the boat that if damaged could compromise the IT.

 

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On 13/01/2021 at 16:57, Loddon said:

That is not the reason 

The reason the metal box is a problem is because it could compromise the grounding of the boat thus rendering the IT ineffective.

To be honest an IT should not even be on the boat but should be next to the supply on the bank as mine was for many years.

I bought an Airlink transformer, possibly the first one they supplied for use on a boat, one of these

https://airlinktransformers.com/product/enclosed-isolating-industrial-transformer-wm3602

This was before they developed the potted version which they did at my suggestion.

Mine was in a metal enclosure that sat next to the supply in the shed at my old mooring.

When I changed moorings 2 years ago some 13 years after it was installed I re-cased it in an HPDE box and it is now in a cupboard at the back of my boat fed by a double insulated cable enclosed in plastic conduit to try and prevent anything that may compromise the boats grounding. I much prefer a transformer off the boat and I even worry about cables feeding into the boat that if damaged could compromise the IT.

 

All fair points.

The "electrically unprotected" cable from the IT to the boat's consumer unit in my case is about 10ft but this is in a secure conduit so unlikely to suffer mechanical damage.

With a shore IT, the "electrically unprotected" cable is somewhat longer and more likely to be damaged being exposed to external elements/mechanical damage.

I guess on balance, in the extreme case of a transformer fire, it's better that it happens off the boat than on it

Is the placement of IT's (if fitted) enforced in the Regulations? Seems like it should be 

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