Quick question about wiring up an Inverter

[Loafer]

 

Where did you buy it? Marina, chandlery, online (from Victron themselves, or eBay, etc etc)?

 

Ah - crossed wires here. I was referring to my £239 2kW NoName PSW inverter. It is centre tapped but didn't mention it in any of the blurb.

 

I don't know what type my Victron was, 'cos it went pop and all the inverter smoke leaked out.

 

I hate Victron.

[Paul C]

 

Ah - crossed wires here. I was referring to my £239 2kW NoName PSW inverter. It is centre tapped but didn't mention it in any of the blurb.

 

I don't know what type my Victron was, 'cos it went pop and all the inverter smoke leaked out.

 

I hate Victron.

 

OK no worries, I'm not familiar with the Victron product range but I imagine if they do both N-E bonded and centre-tapped versions of essentially the same product, its because of regionalisation. I'd expect/hope a marina would source and buy wholesale, the UK variant, while on eBay you might get anything (including the UK version, if you looked specifically for it).

 

Centre tapping is not less safe in itself, but I'd be using double pole switches etc as previously discussed.

[Graham.m]

But then again why not? I don't think you can get a Travelpower in non-centre tapped. As you can see from ISO13297 there is no reason not to have centre tapped. It is cheaper to make I'm sure, but so what? There is no additional requirement for centre tapped systems on a boat - you need double pole RCD/MCB/RCBO anyway.

 

I have been told the Travel Power can be converted or delivered neutral earth.

 

The ISOs are multi-country standards so they have to cover situations that vary country to country. I think people need to keep in mind what their country's base standards are before quote ah but the international reg allows this or that. In my opinion mixing electrical systems is a way to problems, have seen it too often.

 

Oh you also need double pole outlets as well as double pole circuit breakers if fitted

 

OK no worries, I'm not familiar with the Victron product range but I imagine if they do both N-E bonded and centre-tapped versions of essentially the same product, its because of regionalisation. I'd expect/hope a marina would source and buy wholesale, the UK variant, while on eBay you might get anything (including the UK version, if you looked specifically for it).

 

Centre tapping is not less safe in itself, but I'd be using double pole switches etc as previously discussed.

Not in principle, but I have seen mixing the two systems cause problems.

Edited December 11, 2015 by Graham.m

[Paul C]

 

 

Not in principle, but I have seen mixing the two systems cause problems.

 

In what ways? Devices are "earthed" at their source, different sources are isolated from one another so the boat only runs from one source at a time.

[nicknorman]

By way of explaining how a Travelpower works to those that don't know, there is a modified alternator that produces around 300v DC. This DC voltage is then sent to the "magic box" in which is primarily a pair of inductors (one for L and one for "N") driven by transistors. There is no transformer and so by the inherent design it has to be centre tapped. That said, there have been a few variants of Travelpower boxes over the years and the above description is just how mine (2010 vintage) works, possibly earlier versions were different.

 

The fact of the matter is that centre tapped power sources on boats are covered by the only applicable regulations that apply to boat electrics (and of course they only apply to new builds). Thousands of boats have Travelpowers. So it is an absolute non-issue except for a few clowns who don't know what they are talking about. It is amazing that they can think they are right and the entire rest of the industry, manufacturers and regulators are wrong, without them providing a shred of evidence to support their fantasies.

[Graham.m]

 

In what ways? Devices are "earthed" at their source, different sources are isolated from one another so the boat only runs from one source at a time.

 

I wish that were true. That is the way it should be, came a cross one recently where two different sources ,One was centre-tapped the other was neutral-earth, could supply AC to the galley and bathroom at the same time, so one socket was centre-tapped earth another neutral-earth. . Interesting it had passed a BSC inspection recently as setup.

Edited December 11, 2015 by Graham.m

[Dave-Shrop]

 

In what ways? Devices are "earthed" at their source, different sources are isolated from one another so the boat only runs from one source at a time.

As stated on here by some they are using non double pole switched sockets and using circuit breakers in only one pole when on 240 volt centre tapped earth system.

[nicknorman]

As stated on here by some they are using non double pole switched sockets and using circuit breakers in only one pole when on 240 volt centre tapped earth system.

There is no requirement to have double switched sockets with centre tapped, though we have agreed it's probably a good idea. In fact I don't think there is a need to have any switching in sockets, although again it's probably a good idea.

 

All boats should have double pole breakers (RCD at least) regardless of centre tapped or polarised. Nobody here has said they only have / need single pole.

Edited December 11, 2015 by nicknorman

[Graham.m]

But then again why not? I don't think you can get a Travelpower in non-centre tapped. As you can see from ISO13297 there is no reason not to have centre tapped. It is cheaper to make I'm sure, but so what? There is no additional requirement for centre tapped systems on a boat - you need double pole RCD/MCB/RCBO anyway.

 

ISO 13297

7.1.1 In unpolarized systems, double-pole circuit-breakers that open both live and neutral conductors are required.

 

7.3.2 Both conductors of each branch circuit in unpolarized systems shall be provided with overcurrent protection by double-pole circuit-breakers and double-pole switches, if used, at the point of connection to the main panel-board bus.

By way of explaining how a Travelpower works to those that don't know, there is a modified alternator that produces around 300v DC. This DC voltage is then sent to the "magic box" in which is primarily a pair of inductors (one for L and one for "N") driven by transistors. There is no transformer and so by the inherent design it has to be centre tapped. That said, there have been a few variants of Travelpower boxes over the years and the above description is just how mine (2010 vintage) works, possibly earlier versions were different.

 

The fact of the matter is that centre tapped power sources on boats are covered by the only applicable regulations that apply to boat electrics (and of course they only apply to new builds). Thousands of boats have Travelpowers. So it is an absolute non-issue except for a few clowns who don't know what they are talking about. It is amazing that they can think they are right and the entire rest of the industry, manufacturers and regulators are wrong, without them providing a shred of evidence to support their fantasies.

 

When did the ISO 13297 first come into effect? Because all boats from that date will be affected

[cuthound]

Link to Electrolux Travel Post manual.

 

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://flofl.sourceforge.net/new/dir/electrolux-travel-power-manual.pdf&ved=0ahUKEwiJ-aG8u9TJAhVMXRoKHQ2kAHIQFghhMBI&usg=AFQjCNE6ms2h-KTBccUNiX1KMYZSDfBzPg

 

It makes it very clear that it is to be separated from any other ac source, and that the output iscto go through a two pole rcd.

 

Edited to remove letters masquerading as spaces.

Edited December 11, 2015 by cuthound

[Graham.m]

Link to Electrolux Travel Post manual.

 

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://flofl.sourceforge.net/new/dir/electrolux-travel-power-manual.pdf&ved=0ahUKEwiJ-aG8u9TJAhVMXRoKHQ2kAHIQFghhMBI&usg=AFQjCNE6ms2h-KTBccUNiX1KMYZSDfBzPg

 

It makes it very clear that it is to be separated from any other ac source, and that the output iscto go through a two pole rcd.

 

Edited to remove letters masquerading as spaces.

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[nicknorman]

Link to Electrolux Travel Post manual.https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://flofl.sourceforge.net/new/dir/electrolux-travel-power-manual.pdf&ved=0ahUKEwiJ-aG8u9TJAhVMXRoKHQ2kAHIQFghhMBI&usg=AFQjCNE6ms2h-KTBccUNiX1KMYZSDfBzPg

It makes it very clear that it is to be separated from any other ac source, and that the output iscto go through a two pole rcd.

Edited to remove letters masquerading as spaces.

Linky doesn't work unfortunately, but anyway as you say it needs to be kept seperate from any other AC source, not just the live but also the neutral aka the "other live". As far as I know it is de rigeur to use double pole switching to select AC sources anyway. If you didn't, it wouldn't really be a safety hazard but it would cause the Travelpower's Magic smoke to terminally escape!

[Dave-Shrop]

 

Ok that kind of proves my point, there are at least two versions under the same name. Have found what appears to be the correct manual for yours here. Very little info on the AC output but maybe not surprising as the output sockets are clearly designed to operate one or two items of equipment directly not generally for distribution.

 

I would be cautious therefore that the reply Graham received from Victron may not apply to yours, especially since your checks with a multi-meter strongly suggest it is centre tap earthed.

Do not see how you can check with a multi-meter, because there will be lots of electronics connected to the secondary output circuit of the transformer for measuring voltage, current, and frequency and also means to control the voltage which is usually by switching connections to winding taps.

[Paul C]

Yeah see post #2!!!!

[nicknorman]

Do not see how you can check with a multi-meter, because there will be lots of electronics connected to the secondary output circuit of the transformer for measuring voltage, current, and frequency and also means to control the voltage which is usually by switching connections to winding taps.

If you know what you are doing, checks with a multimeter are simple. With it powered up:

live to earth and (not simultaneously) neutral to earth gives zero = fully floating (could make a NE bond)

Live to earth gives 230v, neutral to earth gives zero = polarised with an NE bond already extant

Live to earth gives 115v, neutral to earth gives 115v = centre tapped earth. NE bond will blow it up, but no need.

 

Simples - when you know what you are talking about. By the way I didn't invent this, it's all on Gibbo's website.

[Dave-Shrop]

There is no requirement to have double switched sockets with centre tapped, though we have agreed it's probably a good idea. In fact I don't think there is a need to have any switching in sockets, although again it's probably a good idea.

 

All boats should have double pole breakers (RCD at least) regardless of centre tapped or polarised. Nobody here has said they only have / need single pole.

 

Does not your Travel Power/shore/inverter then feed an AC distribution board feeding individual AC circuits via MCB's, which requires Double pole MCB's for Travel Power and Single pole MCB's for Shore/inverter. Are not the Thousands of boats that have Travel Power and have an AC distribution board feeding individual AC circuits in the same position. I have seen many boats with travel Power and only single MCB's, including hire boats

[nicknorman]

Does not your Travel Power/shore/inverter then feed an AC distribution board feeding individual AC circuits via MCB's, which requires Double pole MCB's for Travel Power and Single pole MCB's for Shore/inverter. Are not the Thousands of boats that have Travel Power and have an AC distribution board feeding individual AC circuits in the same position. I have seen many boats with travel Power and only single MCB's, including hire boats

Our RCBO is double pole, for all the power sources. Are you suggesting that somehow double pole MCB/RCD/RCBO are unsuitable for polarised (ie conventional) power sources? If so, please explain why.

 

I would imagine that the thousands of boats with Travelpowers mostly have double pole breakers, but no doubt there is the odd one incorrectly installed due to "professionals" with no idea about the regulations - or common sense for that matter.

 

Edit: just checked an old version of the regulations dated 2000 ie 15 years old. It states the requirement for double pole over current protection for unpolarised circuits so it's not a new idea. However it has to be said that there seem to be lots of installers around who are oblivious to the regulations, typically they have always done what they have always done and are unreceptive to anyone suggesting it might be wrong.

 

The moral being that if you want a job doing properly, don't put blind faith in a professional.

Edited December 11, 2015 by nicknorman

[Paul C]

 

Does not your Travel Power/shore/inverter then feed an AC distribution board feeding individual AC circuits via MCB's, which requires Double pole MCB's for Travel Power and Single pole MCB's for Shore/inverter. Are not the Thousands of boats that have Travel Power and have an AC distribution board feeding individual AC circuits in the same position. I have seen many boats with travel Power and only single MCB's, including hire boats

 

OK Nick's slightly different in that his boat uses RCBOs, but its acceptable for the MCBs to be single pole and the RCD(s) to be double pole.

[Dave-Shrop]

 

OK Nick's slightly different in that his boat uses RCBOs, but its acceptable for the MCBs to be single pole and the RCD(s) to be double pole.

 

ISO 13297

7.1.1 In unpolarized systems, double-pole circuit-breakers that open both live and neutral conductors are required.

 

7.3.2 Both conductors of each branch circuit in unpolarized systems shall be provided with overcurrent protection by double-pole circuit-breakers and double-pole switches, if used, at the point of connection to the main panel-board bus.

 

Does this not mean that MCB's should be double pole?

[nicknorman]

ISO 13297

7.1.1 In unpolarized systems, double-pole circuit-breakers that open both live and neutral conductors are required.

 

7.3.2 Both conductors of each branch circuit in unpolarized systems shall be provided with overcurrent protection by double-pole circuit-breakers and double-pole switches, if used, at the point of connection to the main panel-board bus.

 

Does this not mean that MCB's should be double pole?

Yes the over current breaker whether it be an MCB or RCBO must be double pole for an unpolarised system, to be compliant with the reg. Otherwise if the MCB trips the "N" still has 115v on it.

 

All that said, and I'm not trying to make a case against the reg, but let's look at the FMEA:

 

MCBs normally trip for 3 reasons:

 

- just using too much power (typically on a 16A system) eg putting the kettle and the tumble drier on. Consequence of having a single pole MCB is nothing.

 

- short between live and neutral. Consequence of having a single pole MCB is nothing as the MCB isolates the fault.

 

- short between Earth and one of live or neutral. If it's the live, the MCB trips and the problem is isolated. If it's the neutral, the MCB isn't going to help. However there is now a massive imbalance between L and N currents and so the RCD (which must always be double pole) trips, the problem is isolated.

 

So I think this explains why, if there are a lot of boats with unpolarised supplies and single pole MCBs, the canals aren't littered with dead bodies with their hair standing straight out.

 

As I said, not trying to argue against the reg because the downside is that if you trip the MCB you might reasonably expect the circuit to be isolated and then for example do some work on the wiring (bad idea but it happens!). But at least there is only 115v which is fairly unlikely to be fatal unless you are really well grounded.

Edited December 11, 2015 by nicknorman

[nicknorman]

Whilst we are on this topic, I think Dave envisages a domestic type consumer unit with lots of MCBs. In my opinion this is generally a bad idea for a narrowboat. The incoming supply is typically limited to 16A, system wiring is typically 2.5mm sq flex and so there should be an overall current limit of 16A. If there are several MCBs in parallel eg for sockets, for the immersion heater, for any mains lighting, for a mains fridge etc then there is no control of the overall max current. Personally I think that just one MCB (which might as well be an RCBO) rated at 16A is the way to go. Unlike a house, if the main AC supply trips it is not a crisis since most boats have 12v lighting etc.

Edited December 11, 2015 by nicknorman

[Graham.m]

Yes the over current breaker whether it be an MCB or RCBO must be double pole for an unpolarised system, to be compliant with the reg. Otherwise if the MCB trips the "N" still has 115v on it.

 

All that said, and I'm not trying to make a case against the reg, but let's look at the FMA:

 

MCBs normally trip for 3 reasons:

 

- just using too much power (typically on a 16A system) eg putting the kettle and the tumble drier on. Consequence of having a single pole MCB is nothing.

 

- short between live and neutral. Consequence of having a single pole MCB is nothing as the MCB isolates the fault.

 

- short between Earth and one of live or neutral. If it's the live, the MCB trips and the problem is isolated. If it's the neutral, the MCB isn't going to help. However there is now a massive imbalance between L and N currents and so the RCD (which must always be double pole) trips, the problem is isolated.

 

So I think this explains why, if there are a lot of boats with unpolarised supplies and single pole MCBs, the canals aren't littered with dead bodies with their hair standing straight out.

I think your last is the process problem, and you realised it hence your next post trying to work a way out of it.

 

The RCD I would suggest should be of an appropriate rating to protect the source, ie 16A. Several boats I know have more than one circuit, including a lighting ring. Thus following your logic if there is a fault on the unfused live the result is the boat loses all its AC including lighting. Rather than if 2pole MCBs were fitted only the faulty circuit would be lost. Including lighting where fitted. Could loss of lighting lead to an accident. Possibly

 

Maybe those guys n gals who wrote the regs knew a bit better than you.

Edited December 11, 2015 by Graham.m

[Paul C]

 

ISO 13297

7.1.1 In unpolarized systems, double-pole circuit-breakers that open both live and neutral conductors are required.

 

7.3.2 Both conductors of each branch circuit in unpolarized systems shall be provided with overcurrent protection by double-pole circuit-breakers and double-pole switches, if used, at the point of connection to the main panel-board bus.

 

Does this not mean that MCB's should be double pole?

 

No worries, I stand corrected! I've never seen double pole MCBs but they obviously exist.

[Graham.m]

I know of several boats with 6/7kVA generators. In your view there is no reason why these should not be centre-tapped earth.

[nicknorman]

The RCD I would suggest should be of an appropriate rating to protect the source, ie 16A.

Trouble is after 4 gin and tonics (well it's Friday night) I have temporarily lost the will to resist replying to your random froth. An RCD doesn't trip on an over-current, so to talk about a 16A RCD protecting the source is utter rubbish. You really have no idea what you are talking about.