inverter

[steve 24]

i am new to boating and my boat needs a bit of TLC i need to know how to wire up a mobitronic pure sine wave inverter 1000w

firstly do the power input go to the terminals on the leisure battery ? and how would i get the 240v sockets to power up from it 

there are a number of small jobs that need doing plus one large one which is central heating and boiler 

i was thinking about a diesel boiler but not sure yet as i am trying to weigh up the pro,s & cons of them

thankyou in advance for any advice

[Tony Brooks]

Your questions worry me. 240 volts can and will kill. If I start on about RCDs, RCBOs, & MCBs will you understand what I am on about?

How about calculating the cable size for the inverter? I note no mention of a fuse to protect the 12V leads that will supply the inverter.

Have you done a power/energy audit to make sure your battery bank size and charging regime are adequate for the inverter?

Although you do not say so implicitly it sounds as if you already have 240 volt sockets aboard. This implies a shoreline. If so what mechanism/procedure will you employ to ensure the shoreline and inverter are not in use together (unless its a very expensive inverter that allows for that). Ignore this and the inverter is likely to produce the magic smoke. If there is a shoreline do you understand the importance of galvanic isolators or isolation transformers.

I am not trying to make this sound complicated but there is a minimum standard of knowledge required to install a safe and reliable 240V AC system onto a boat. Do you have that knowledge? If not are you willing to acquire it or will it be easier to employ someone who has that knowledge.

[Tony Brooks]

I hoped that you would come back and give us some idea about your level of knowledge in electrical matters, your practical ability, and more about the boat so we could give relevant and safe advice.

What I think it safe to say is that The inverter will draw around 100 amps plus rather more as it starts up. Simply buying cable marked as 100 amps may or may not do because the conductor thickness required depends upon the cable length. The longer the cable the more lost voltage (voltdrop) so the thicket the cable required. So you can see that without a cable run length (out and back) we can not help with the cable size.

You will require a fuse close to wherever the positive cable picks up the 12V supply but to a degree its size will be governed by the cable conductor cross sectional area because the fuse is there to protect the cable UNLESS the instructions for the inverter says differently.

A very significant number of battery master switches used on narrowboats are of very poor quality and suddenly adding a 100 amp + load could well be enough to encourage early failure so you may be best advised to fit a separate master switch for the inverter.

So the 12V wiring will be like this, all using thick cable suitable for its length and current: battery pos. - new master switch - fuse - 12V + input to inverter (note - the fuse could be between battery and master switch depending upon cable length and position). Using the same sized cable from inverter 12V neg. terminal - battery neg. Observe no more than four connections on the battery clamps so if not possible suitably rated bus bars may be required. Also note the pos. and neg. should run to opposite ends of the battery bank. Cable to be secured very frequently, say every 4 to 6 inches.

 

The inverter output at mains voltage is a very different thing. A household electrician may try to wire the mains part using single strand twin and earth cable as used in house. This is bad practice and may lead to early failure caused by vibrations. Mains multi-strand flex is required with a minimum of 19 (I think) strands abut probably a lot more. To do this is not a BSS failure but if the boat has an RCD certificate it would invalidate the certificate and may involve you in a criminal act if you sold the boat.

If you have a shoreline socket the you need some form of "change over" device so you can only power the boat's mains circuit from one source at a time.

The inverter mains output would be something like this but take professional advice: Inverter mains output terminals - change over device - RCD - MCB(s) (or both as an RCBO(s)).  You might already have the RCD & MCB fitted if you have a shoreline. 

 

You also need to ensure the mains hull earth bond (so the RCD can work in case of a dangerous fault) is compatible with your inverter's designs and is fitted with an isolations transformer of galvanic isolator that will protect the hull from corrosion  when on the shoreline.

 

As you have not come back with more information this is given subject to you confirming bets practice by taking professional advice.

 

[Chewbacka]

Tony - I am fairly sure that this bit is not correct "To do this is not a BSS failure but if the boat has an RCD certificate it would invalidate the certificate and may involve you in a criminal act if you sold the boat."   The RCD certificate relates only to the time of construction.  Modifications after sale do not make the original certificate invalid, however you are still required to ensure the safety of the craft and a negligent modification/installation that subsequently harmed someone could result in action against you.  Likewise when the regulation requirements are updated  (after the RCD cert has been issued) you are under no obligation to update the craft to ensure compliance to the latest version.

[David Mack]

1 hour ago, Chewbacka said:

Tony - I am fairly sure that this bit is not correct "To do this is not a BSS failure but if the boat has an RCD certificate it would invalidate the certificate and may involve you in a criminal act if you sold the boat."   The RCD certificate relates only to the time of construction.  Modifications after sale do not make the original certificate invalid, however you are still required to ensure the safety of the craft and a negligent modification/installation that subsequently harmed someone could result in action against you.  Likewise when the regulation requirements are updated  (after the RCD cert has been issued) you are under no obligation to update the craft to ensure compliance to the latest version.

Strictly, the RCD relates to its condition when it is first placed on the EU market. But the effect is much the same - once the boat has been sold the owner can do things which don't comply with RCD requirements, and a subsequent sale in that condition is perfectly legal.

[stegra]

1 hour ago, David Mack said:

Strictly, the RCD relates to its condition when it is first placed on the EU market. But the effect is much the same - once the boat has been sold the owner can do things which don't comply with RCD requirements, and a subsequent sale in that condition is perfectly legal.

I take it that bit is supposed to mean something similar to a motor vehicle's 'date of fist registration' rather than a self fit-out being placed on the market four years after the RCD was issued, having been used by its owner during that time.

[Tony Brooks]

Notice the words "may involve", not "will involve".

There is also a question about selling a boat as having an RCD certificate when the systems that certificate relates to are modified or added in a way that means that certificate no longer applies to the whole boat. We can ague if that is a civil rather than criminal matter but if the seller relied upon the statement that the boat had a RCD and a RCD certificate was handed over it looks very like fraud to me. There would certainly be a civil remedy.

[Chewbacka]

Not at all.  The RCD is like an MOT for a car, it is only valid against the condition of the vehicle on the day it is issued.  If you sold the boat saying "it has an RCD cert which ensures it was completely built to 'best practice' etc", then it would be a bit iffy if you had made non-compliant mods and did not disclose them.  If however you sold it as 'sold as seen' and answered any questions truthfully and simply said that the boat was supplied with an RCD cert, then I don't see any real problems.  However if you have made mods you know to be unsafe then I think you must disclose them.

[David Mack]

5 hours ago, stegra said:

I take it that bit is supposed to mean something similar to a motor vehicle's 'date of fist registration' rather than a self fit-out being placed on the market four years after the RCD was issued, having been used by its owner during that time.

No. It refers to a recreational craft being first placed on the EU market, which must comply with the RCD, the exception being craft built for own use and placed on the EU market after 5 or more years. A self-built boat put on the EU market after (say) 3 years needs to comply with the RCD at the time it is put on the market.