Ac system requirements

[boater123]

Before embarking on installation of my AC system, if anyone could share any information on the following I would appreciate it.

 

According to the RCD (recreational craft directive) is the following AC system acceptable? (I shall start form shoreline connection to AC outlets)

 

Shore line connection plug fed into an RCD (residual current device) within 0.5 meters form the plug, the RCD shall be housed in a waterproof box next to the plug (a garage box). This RCD shall feed into two single pole MCBs, one connected to the diesel immersion heater, and the other connected to the inverter.

Out of the inverter I propose to feed another RCD, housed within the electrical cupboard which shall feed two other single pole MCBs, a 10A MCB for a ring circuit of ac sockets (12 sockets, which I know is a large amount for one ring, but with 2.5mm cable and a smaller MCB this will reduce loading the sockets with the full whack of the 3KW inverter), and the other 12A MCB for a washing machine.

 

My main question is... Does the galvanic isolator need to be connected at both RCDS or would connecting it to the first RCD ground the inverter through the galvanic isolator? Or do both RCDs and Inverter require grounding through the galvanic isolator.

 

I will also be connecting the inverter to the batteries but that shall be for another day.

 

Thanks,

 

Will

[WotEver]

The GI goes immediately after the shore power connector.

 

Tony

[WotEver]

Other thoughts - be sure to use 2.5mm² flex and not twin and earth to wire the ring. If you want to do a really good job then terminate the flex with bootlaces ferrules at each socket. Domestic 13A socket outlets are designed to clamp onto solid, so the ferrules replicate that.

 

Be sure to link Neutral and Earth at the inverter.

 

Having two RCDs (well, 3 if you count the one on the bollard) will involve you in a game of "find the tripped one" if you do ever have a fault, so ensure that the garage consumer unit is easily accessible.

 

Tony

 

Edited for phat phingers

Edited February 29, 2016 by WotEver

[Loafer]

Other thoughts - be sure to use 2.5mm² flex and not twin and earth to wire the ring. If you want to do a really good job then terminate the flex with bootlaces ferrules at each socket. Domestic 13A socket outlets are designed to clamp onto solid, so the ferrules replicate that.

 

Be sure to link Neutral and Earth at the inverter.

 

Having two RCDs (well, 3 if you count the one on the bollard) will involve you in a game of "find the tripped one" if you do ever have a fault, so ensure that the garage consumer unit is easily accessible.

 

Tony

 

Edited for phat phingers

 

Before linking the inverter's neutral and earth, be sure that your inverter can allow this. Otherwise there is a distinct possibility of your inverter losing all of its magic smoke.

[Chewbacka]

Before embarking on installation of my AC system, if anyone could share any information on the following I would appreciate it.

 

According to the RCD (recreational craft directive) is the following AC system acceptable? (I shall start form shoreline connection to AC outlets)

 

Shore line connection plug fed into an RCD (residual current device) within 0.5 meters form the plug, the RCD shall be housed in a waterproof box next to the plug (a garage box). This RCD shall feed into two single pole MCBs, one connected to the diesel immersion heater, and the other connected to the inverter.

Out of the inverter I propose to feed another RCD, housed within the electrical cupboard which shall feed two other single pole MCBs, a 10A MCB for a ring circuit of ac sockets (12 sockets, which I know is a large amount for one ring, but with 2.5mm cable and a smaller MCB this will reduce loading the sockets with the full whack of the 3KW inverter), and the other 12A MCB for a washing machine.

 

My main question is... Does the galvanic isolator need to be connected at both RCDS or would connecting it to the first RCD ground the inverter through the galvanic isolator? Or do both RCDs and Inverter require grounding through the galvanic isolator.

 

I will also be connecting the inverter to the batteries but that shall be for another day.

 

Thanks,

 

Will

2.5mm2 is fine for as many sockets as you wish on your system as the shore supply is a max of 16amps and your inverter is 3kw. so you will not overload the cable. For a 3kw inverter I would increase the socket breaker to avoid it tripping at a load of less 3kw.

[WotEver]

For a 3kw inverter I would increase the socket breaker to avoid it tripping at a load of less 3kw.

OP stated that the 10A breaker was intentionally to prevent the full 3kW being drawn via the sockets.

 

Don't know why, but that's what he said.

 

Tony

 

Before linking the inverter's neutral and earth, be sure that your inverter can allow this. Otherwise there is a distinct possibility of your inverter losing all of its magic smoke.

True, but unlikely that a 3kW inverter would be a Mickey Mouse jobbie.

 

Tony

Edited February 29, 2016 by WotEver

[Chewbacka]

Other thoughts - be sure to use 2.5mm² flex and not twin and earth to wire the ring. If you want to do a really good job then terminate the flex with bootlaces ferrules at each socket. Domestic 13A socket outlets are designed to clamp onto solid, so the ferrules replicate that.

 

Be sure to link Neutral and Earth at the inverter.

 

Having two RCDs (well, 3 if you count the one on the bollard) will involve you in a game of "find the tripped one" if you do ever have a fault, so ensure that the garage consumer unit is easily accessible.

 

Tony

 

Edited for phat phingers

From your initial post it sounds like you have an inverter/charger combi unit. This may also have a pass through so that shore power is supplied through the inverter, in which case you should not link the neutral and earth together if it will also link the shore neutral to the earth as this is not allowed.

There may be a relay in the inverter which will do this for you.

[WotEver]

From your initial post it sounds like you have an inverter/charger combi unit. This may also have a pass through so that shore power is supplied through the inverter, in which case you should not link the neutral and earth together if it will also link the shore neutral to the earth as this is not allowed.

There may be a relay in the inverter which will do this for you.

A very valid point that I had missed.

 

OP - what inverter are you installing?

[Paul C]

Is the inverter an inverter or a combi?

[nicknorman]

Yes I would not artificially limit the max current on the socket ring. Use a 16A breaker. Use an awareness of what is switched on to avoid overload!

 

Not quite sure what you mean by "diesel immersion heater" but just a thought, have you made a conscious decision to not allow the immersion to be powered by the inverter? If so, fine, that makes it foolproof but on our system we have the immersion powered via the Combi inverter so it can be on just with the inverter. I find this useful for a quick run of the engine for hot water - as well as the calorifier we can have the immersion on to add another 1kw of heating (supplied by the 175A alternator) and of course the extra load helps the engine to heat up quicker. Of course it then remains your responsibility to ensure the immersion is not left on after you stop the engine. It's is foolproofedness vs flexibility. Your choice!

 

Use of ferrules on stranded cable is mandatory for the RCD (rec craft dir).

 

Just going to check if single pole breakers are allowed, I have a vague feeling they are not.

[Chewbacka]

OP stated that the 10A breaker was intentionally to prevent the full 3kW being drawn via the sockets.

 

Don't know why, but that's what he said.

 

..........................

I got the impression that he was using a 10A mcb to protect the circuit as he felt the number of sockets was excessive. If so he can use a bigger mcb. However if he does want to limit the power draw this is an odd way to do it.

[WotEver]

Use of ferrules on stranded cable is mandatory for the RCD (rec craft dir).

Well I didn't know that. There again, I've never read the RCD specs. It's something I always do just because it's good practice but I never knew it was mandatory.

 

Tony

I got the impression that he was using a 10A mcb to protect the circuit as he felt the number of sockets was excessive. If so he can use a bigger mcb. However if he does want to limit the power draw this is an odd way to do it.

I guess we require some clarification.

 

Tony

[bottle]

My first thought after reading the original post was... get in a professional,

 

So many things wrong in the thought, planning, knowledge process.

[David Mack]

Shore line connection plug ...

Well for starters your shoreline connection should not have a plug on it at the boat end.

[nicknorman]

Well I didn't know that. There again, I've never read the RCD specs. It's something I always do just because it's good practice but I never knew it was mandatory.

Tony

 

I guess we require some clarification.

Tony

From ISO 13297 "small craft - electrical systems - alternating current installations":

 

11.7 All conductors shall have suitable terminals installed, ie no bare wires to stud or screw connections.

 

The ISOs are available FoC here (which is great because they are really expensive to buy.

 

http://www.manchester.gov.uk/info/200062/libraries/110/online_reference_library/4

Edited February 29, 2016 by nicknorman

[cuthound]

OP stated that the 10A breaker was intentionally to prevent the full 3kW being drawn via the sockets.

Don't know why, but that's what he said.

Tony

 

True, but unlikely that a 3kW inverter would be a Mickey Mouse jobbie.

Tony

Most 3kW inverters have a mains pass through facility, so if the OP has one of thrse he could just use one RCD after the inverter output.

[Paul C]

Before embarking on installation of my AC system, if anyone could share any information on the following I would appreciate it.

 

According to the RCD (recreational craft directive) is the following AC system acceptable? (I shall start form shoreline connection to AC outlets)

 

Shore line connection plug fed into an RCD (residual current device) within 0.5 meters form the plug, the RCD shall be housed in a waterproof box next to the plug (a garage box). This RCD shall feed into two single pole MCBs, one connected to the diesel immersion heater, and the other connected to the inverter.

Out of the inverter I propose to feed another RCD, housed within the electrical cupboard which shall feed two other single pole MCBs, a 10A MCB for a ring circuit of ac sockets (12 sockets, which I know is a large amount for one ring, but with 2.5mm cable and a smaller MCB this will reduce loading the sockets with the full whack of the 3KW inverter), and the other 12A MCB for a washing machine.

 

My main question is... Does the galvanic isolator need to be connected at both RCDS or would connecting it to the first RCD ground the inverter through the galvanic isolator? Or do both RCDs and Inverter require grounding through the galvanic isolator.

 

I will also be connecting the inverter to the batteries but that shall be for another day.

 

Thanks,

 

Will

 

I got about half way through then my head exploded. After I scraped up the bits of brain, stuffed them into my head and duck-taped my skull back together, I realised the sensible thing to do is suggest you draw a diagram. A picture is worth 1000 words. A technical diagram is worth doing for your own reference, mainly, but would illustrate it to the forum much better too.

 

I drew 3 or 4 diagrams of my boat electrics before I was 100% happy with it, and kept them for my own reference.

[nicknorman]

Oh by the way, single pole breakers are allowed provided the system is polarised.

[cuthound]

Oh by the way, single pole breakers are allowed provided the system is polarised.

Do you mean if it has a correct polarity indicator fitted?

[nicknorman]

Do you mean if it has a correct polarity indicator fitted?

No, in this context polarised means that the two power conductors are differentiated into live and neutral, as opposed to being centre tapped/both half live. In other words with NE bond.

[boater123]

Thanks for the all the information so far.

I am do plan to have an electrician install all the equipment, but as fitting out on the water in London, they are like gold dust to get a hold of for work. Therefore I aim to purchase the required equipment so I can have it all ready for a professional to install.

I plan to have a victron multiplus charger inverter 3KW.

As CC the 10A MCB was an idea to discourage high AC power use, and an idea i shall put to bed.

I shall put together a diagram to aid my description.

 

Thanks again for all the information,

 

Will

[cuthound]

No, in this context polarised means that the two power conductors are differentiated into live and neutral, as opposed to being centre tapped/both half live. In other words with NE bond.

Yes, I see a centre tapped device couldn't be guaranteed to trip a single pole mcb. I thought we had established that a 3kW inverter was unlikely event be centre tapped though?

[Tiggs]

Other thoughts - be sure to use 2.5mm² flex and not twin and earth to wire the ring. If you want to do a really good job then terminate the flex with bootlaces ferrules at each socket. Domestic 13A socket outlets are designed to clamp onto solid, so the ferrules replicate that.

 

Yes, use flex but I wouldn't use any ferrules. 1. I don't believe that the sockets are specifically "designed" for solid wires. 2. Using ferrules immediately negates one of the main reasons for using flex, the compression of the flexible wire means that the screws in the sockets don't come loose under vibration of the boat.

 

(I'm sure people will disagree with this but my experience has proved that I am right on this)

[boater123]

With regards to the immersion heater... the diesel boiler we are using has both options of using diesel and an electric immersion heater, with a view when you are connected to the shoreline you can have constant hot water via the immersion.

Again as cc, I only want diesel to heat the water therefore will not power the immersion via the batteries.

[WotEver]

Yes, use flex but I wouldn't use any ferrules. 1. I don't believe that the sockets are specifically "designed" for solid wires. 2. Using ferrules immediately negates one of the main reasons for using flex, the compression of the flexible wire means that the screws in the sockets don't come loose under vibration of the boat.

 

(I'm sure people will disagree with this but my experience has proved that I am right on this)

Yes, I'm afraid that you are indeed wrong. As Nick has pointed out, ferrules are mandatory to comply with the RCD.

 

Properly tightened screws will bite hard into a ferrule making unscrewing by vibration virtually impossible.

 

Tony

 

Oh, and yes, of course socket outlets are designed for solid wire - that's what they're wired with in every building in the land. If they were designed for stranded cable then they would have a flat spring under the screw to clamp the strands properly instead of having the strands climb up the sides of the screw (as happens without a ferrule).

Edited February 29, 2016 by WotEver