Mains wiring using Inverter/Charger combi

[robtheplod]

Hi All

 

Does this look correct for wiring on the mains side of a combi?  I've assumed RCD is needed on both the input and output but cant seem to find if this is the recommended way?

 

 

[Tony Brooks]

Out of my field, but you should have an RCD & MCB or an RCBO in the shoreside bollard that will protect the shoreline and connector, so why do you need one on the boat as well. You definitely need one after the inverter.

[SLC]

Get the advice of a professional. I have been told by a BSS surveyor that it is a requirement to have a RCD/MCB fitted on the shore input side (regardless of what may be fitted on the bollard). The drawing does not show if there are any mains powered appliances (e.g. washing machine or immersion heater) - these will require their own MCB/RCD. Also RCD/MCB must be appropriately rated as indeed must the cables be.

Remember, you are protecting your boat, yourself and your friends and should not rely on what the shore power provider thinks is appropriate. Please get professional advice.

[BEngo]

Tony is right,.  However  if you are also going to use the input connection for a generator *and* there is a long run of cable from the input point to the inverter/charger it is arguable that an RCD or RCBO near the  connection is safest.

 

Think about a galvanized isolator or an isolation transformer in the input line if you are going to be on shoreline for long spells.

 

Consider how the mains outlets are configured.  Anything you do not want to run off the inverter, such as immersion heaters, should be connected to the mains before the inverter.

 

N

 

[Alan de Enfield]

11 minutes ago, SLC said:

Get the advice of a professional. I have been told by a BSS surveyor that it is a requirement to have a RCD/MCB fitted on the shore input side (regardless of what may be fitted on the bollard). The drawing does not show if there are any mains powered appliances (e.g. washing machine or immersion heater) - these will require their own MCB/RCD. Also RCD/MCB must be appropriately rated as indeed must the cables be.

Remember, you are protecting your boat, yourself and your friends and should not rely on what the shore power provider thinks is appropriate. Please get professional advice.

 

Then unless your boat is a commercial boat, I suggest you report that examiner to the BSS and suggest he is removed from the approved list.

 

He is incorrect - rather than me just saying so - read the BSS section 3:9:2 where you will see that it only a requirement for commercial boats.

 

It really annoys me when examiners invent their own ruls and take advantage of boat owneres who have not read the requirements and do not argue with them.

 

All of the requiremens for 230v AC  in the BSS are simply advisory for leisure boats and you CANNOT fail the BSS if you do not have what they want.

 

 

 

[GUMPY]

No RCD needed on the input unless it is split off to power stuff independent of the inverter.

The PDF shows mine is wired as I have the choice of immersion/washing machine running from the shore line or the inverter.

You can of course ignore the WM / immersion circuit.

Don't forget some kind of isolation for the supply earth either a GI or a transformer.

RCD/RCBO are there to protect the oomans so need to cover the final sockets where the oomans might be.

230vAC NEW 2_0.pdf

[Alan de Enfield]

6 minutes ago, Loddon said:

No RCD needed on the input unless it is split off to power stuff independent of the inverter.

The PDF shows mine is wired as I have the choice of immersion/washing machine running from the shore line or the inverter.

You can of course ignore the WM / immersion circuit.

Don't forget some kind of isolation for the supply earth either a GI or a transformer.

RCD/RCBO are there to protect the oomans so need to cover the final sockets where the oomans might be.

230vAC NEW 2_0.pdf 19.29 kB · 0 downloads

 

 

Completely agree it is 'good practice' and improves safety - but I reiterate, whilst YOU may want to do it, the BSS cannot fail your boat if you don't, or demand that you MUST fit it (like they did for me).

 

It is clearly stated in the BSS Guidance that it is simply an 'advisory', Its just a shame that the BSS employ examiners who seem to be unable to read.

[nicknorman]

3 hours ago, robtheplod said:

Hi All

 

Does this look correct for wiring on the mains side of a combi?  I've assumed RCD is needed on both the input and output but cant seem to find if this is the recommended way?

 

 

As written, the first rcd/mcb is superfluous. As other have said, only advisable if you are taking a tapping off before the Combi to run eg an immersion heater or some other thing that you never want to run from the inverter. Our immersion heater is after the Combi since we do sometimes want to run it off the inverter, hence we have just the one rcd/mcb.

[robtheplod]

So looking at the chat, the incoming mains after its passed the GI can go straight to the combi. Combi output passes through RCD then a MCB for each circuit (assuming immersion etc in this as well (subject to below!)

 

Interesting Nick that you sometimes use your immersion from the combi ... i always thought it would kill it... I have a 1kw element and a bank of 4 x 130ah LA batteries.... not sure they would cope??

[GUMPY]

I run my immersion/washing machine  from the combi, immersion for 15 minutes heats the top of the tank enough for two showers.

1kW immersion for 15 minutes equals somewhere about 23Ah or 6.5% from the batteries easily doable from 350Ah of batteries but NOT on a regular basis.

Edited April 26, 2023 by Loddon

[nicknorman]

1 hour ago, robtheplod said:

So looking at the chat, the incoming mains after its passed the GI can go straight to the combi. Combi output passes through RCD then a MCB for each circuit (assuming immersion etc in this as well (subject to below!)

 

Interesting Nick that you sometimes use your immersion from the combi ... i always thought it would kill it... I have a 1kw element and a bank of 4 x 130ah LA batteries.... not sure they would cope??

Immersion heater is 1kw, Combi is 2500va so it runs it easily. We have a slightly more complex system in that we have a travelpower that can feed into the Combi input. The shore power and the travelpower both go into an automatic changeover switch. If shore power is available, it is connected to the Combi. If shore power isn’t available, the travelpower is connected to the Combi. So if I want hot water fast I can start the engine, put the travelpower on and put the immersion heater on. Travelpower powers the immersion and there is a bit more load on the engine which helps it to warm up quicker.

 

These days with Li batteries I sometimes put the immersion on powered by the batteries. We have about 6kwh of battery power so if I run the immersion for an hour, that uses about 17% of capacity.

 

Actually things can be slightly more complicated for you depending on what you think the maximum ac load will be. The shore inlet is limited to 16A which is around 3.5kW. If that is enough (and it is for most people!), then just have one 16A mcb between the Combi and everything else. If you have several mcbs feeding different circuits, when all are in use you can exceed 16A and overload the 16A shore inlet wiring. So just have the one.

 

If you really want to be able to exceed 3.5kW by using the Combi in power support mode (16A from the shore power, plus extra from the batteries via inverter) then you really need a 16A breaker before the Combi and various breakers after the Combi whose total exceeds 16A. But that is making things much more complex and personally I don’t see the point.

 

 

 

Edited April 26, 2023 by nicknorman

[jonathanA]

always worth a look the smartguage website - just about every option of rcd/mcb/change over switches you can think of and why you would do it. 

 

http://www.smartgauge.co.uk/nb_ac_sys.html

 

in my case I found that my perpetual energy idea of battery - inverter -charger-battery didn't work, so have arranged my change over switch so that the charger and immersion heater can't be powered from the inverter and only have one 'consumer unit'   so technically slightly complex but operationally simple... SWMBO only needs to know there is a changeover switch to get her TV working when not on shorepower....  

[nicknorman]

10 minutes ago, jonathanA said:

always worth a look the smartguage website - just about every option of rcd/mcb/change over switches you can think of and why you would do it. 

 

http://www.smartgauge.co.uk/nb_ac_sys.html

 

in my case I found that my perpetual energy idea of battery - inverter -charger-battery didn't work, so have arranged my change over switch so that the charger and immersion heater can't be powered from the inverter and only have one 'consumer unit'   so technically slightly complex but operationally simple... SWMBO only needs to know there is a changeover switch to get her TV working when not on shorepower....  

 

This is the joy of a Combi, automatic switchover between charger and inverter and no chance of the batteries being used to charge the batteries!

[robtheplod]

Thanks for the replies so far....

 

Thinking if its possible/permitted for mains input and two outputs to share a single consumer unit (obviously no busbars inside used and all will be internally seperate) - does this look outrageous?

 

[ditchcrawler]

Why not have something like this and one AC out put from the inverter to it. You may need different size breakers, just an example 

5 minutes ago, robtheplod said:

Thanks for the replies so far....

 

Thinking if its possible/permitted for mains input and two outputs to share a single consumer unit (obviously no busbars inside used and all will be internally seperate) - does this look outrageous?

 

This one is better sized YORKING 2 Way Garage IP65 Weatherproof Circuit Breaker Consumer Unit Enclosure C16 30mA RCD MCB Fuse Box for Workshops Garage : Amazon.co.uk: DIY & Tools