Ac electrics

[John Lewis]

Hello all, I have a joint where my Ac electric cable comes out from wall panels, just short of RCD.

 

what is the best way to make an electrical joint, Im using a standard screw in junction box at the moment.

 

thanks.

[BEngo]

Depends on the cables really.  If the cables are round ones then there are waterproof junction boxes, with glands for the cables.  Some have connectors, others you can fit wago type connectors.

https://www.tlc-direct.co.uk/Products/KBJB004.html?source=adwords&ad_position=&ad_id=415703895075&placement=&kw=&network=u&matchtype=&ad_type=&product_id=KBJB004&product_partition_id=351476229327&campaign=shopping_accessories&version=finalurl_v3&gclid=EAIaIQobChMI27eZxvPv6QIVSbTtCh2iTA5aEAQYAyABEgJQYfD_BwE

If the cables are flat twin and earth they need to be replaced as they are not suitable for boat work.

 

What you have might be OK, it depends on the junction box, and exactly where it is located.

 

N

[Jen-in-Wellies]

If it is a junction box designed for normal domestic solid cored twin and earth, then boot lace ferrules on the multi strand wire you should be using is a good idea.

Jen

[ditchcrawler]

Can you not replace the piece of cable for a longer one

[John Lewis]

11 minutes ago, ditchcrawler said:

Can you not replace the piece of cable for a longer one

It runs in through back of panelling, through trunking, and yes its artic blue.

 

I remember now there is a break there as I wanted to put a plug, to be able to connect to AC mains in or switch over to my 2Kw inverter.

 

Is there a junction which allows a connection 3 way, like a t connection in plumbing...

 

So when mains is not connected I can plug this 3rd connection in to my inverter via a plug.

 

That would then power the 240V up this wall..

 

 

Does that make sense?

 

 

 

[system 4-50]

.

Edited June 7, 2020 by system 4-50

[BEngo]

Yes.  You need a 250 V AC,  16 A, 2 pole,  break before make  changeover switch.  The break before make bit is important so your inverter cannot ever  be connected to the mains.

https://www.cef.co.uk/catalogue/products/1780467-32a-2p-surface-mounting-3-position-changeover-switch-ip65

Would be ideal although 32A is more than enough.

Connect one input to the shore supply  and one input to the inverter.  Connect the output to the RCD and distribution board.  Connect all the earth wires together.

You should fit an isolation transformer or Galvanic Isolator in the incoming mains lead.

 

N

Edited June 7, 2020 by BEngo

[Jen-in-Wellies]

19 minutes ago, John Lewis said:

It runs in through back of panelling, through trunking, and yes its artic blue.

 

I remember now there is a break there as I wanted to put a plug, to be able to connect to AC mains in or switch over to my 2Kw inverter.

 

Is there a junction which allows a connection 3 way, like a t connection in plumbing...

 

So when mains is not connected I can plug this 3rd connection in to my inverter via a plug.

 

That would then power the 240V up this wall..

 

 

Does that make sense?

 

 

 

An easy and cheap way to do it without risking accidentally connecting both inverter and mains outputs is to use the usual 16A plugs and sockets.

Have one of these as the input to the consumer unit

https://www.screwfix.com/p/abb-16a-2p-e-surface-plug-250v/6490f

 

Then have the output from the inverter and the mains coming in from the shore line each on one of these and plug the appropriate one in to the socket above.

https://www.screwfix.com/p/abb-16a-2p-e-connector-250v/2264x

 

Similar effect to the Break Before Make switch that @BEngo describes, but cheaper. Only one power source can be connected to the boat at any time. Having both shore and inverter mains meeting will release the expensive magic smoke.

[John Lewis]

22 minutes ago, BEngo said:

Yes.  You need a 250 V AC,  16 A, 2 pole,  break before make  changeover switch.  The break before make bit is important so your inverter cannot ever  be connected to the mains.

https://www.cef.co.uk/catalogue/products/1780467-32a-2p-surface-mounting-3-position-changeover-switch-ip65

Would be ideal although 32A is more than enough.

Connect one input to the shore supply  and one input to the inverter.  Connect the output to the RCD and distribution board.  Connect all the earth wires together.

You should fit an isolation transformer or Galvanic Isolator in the incoming mains lead.

 

N

ah yes, I get you. might be a proper job.

 

As Jen says maybe the original plug/socket may work.

 

I just thought the socket would be limiting, as it typically has just 16amp fuses I there doesn't it?

 

Where as I have a 32amp I think coming out of RCD..

What about this one - just a changeover switch I think..

https://www.cef.co.uk/catalogue/products/1780798

[Jen-in-Wellies]

What capacity shore bollard are you connected to? 16 (or lower), or 32A? The sockets on 32A shore bollards are different from 16A ones. What size inverter do you have? A 3KW inverter can output a maximum of 12.5A at 240V, so 16A rated things will be fine. Over specified fittings for the current being handled are fine. Under specified ones are not.

Jen

[ditchcrawler]

59 minutes ago, John Lewis said:

 

 

So when mains is not connected I can plug this 3rd connection in to my inverter via a plug.

 

That would then power the 240V up this wall..

 

 

 

 

 

 

DO not do that

[BEngo]

33 minutes ago, John Lewis said:

ah yes, I get you. might be a proper job.

 

As Jen says maybe the original plug/socket may work.

 

I just thought the socket would be limiting, as it typically has just 16amp fuses I there doesn't it?

 

Where as I have a 32amp I think coming out of RCD..

What about this one - just a changeover switch I think..

https://www.cef.co.uk/catalogue/products/1780798

Plugs and socket works, and is wot I use with a built in genny  but that was not the question you asked?.  If going that way you need shrouded receptacles on the input plugs and the visible pins on the single socket fixed to the boat.  Called a fixed appliance inlet unless you are Screwfix and call it a surface plug.  Item 6490F.  Do not use a surface socket.

 

 

No fuses in a 16A plug, or a 32A for that matter. The mains inlet should be fused at the bollard and have an RCD.  If you are thinking about using 32A you need to look carefully at your existing cabling.  2.5mm squared Arctic blue is not rated for 32A   4mm sq may be, but do check.

 

The switch you link to is good for up to 20A so OK for 16A but  not OK with 32A input. you will also need to find a suitable panel and enclosure to make the connections waterproof, again as your original query.

 

N

 

[John Lewis]

Cheers Bengo, yes its 16Amp out of RCD..

 

Basically have a junction at this spot, and thought it best to have a socket to switch over to the inverter when off grid.

 

Is a shrouded receptacle like the blue plug that connects boat externally to landline?

[ditchcrawler]

1 hour ago, John Lewis said:

Cheers Bengo, yes its 16Amp out of RCD..

 

Basically have a junction at this spot, and thought it best to have a socket to switch over to the inverter when off grid.

 

Is a shrouded receptacle like the blue plug that connects boat externally to landline?

If you are planning to feed this junction bog from the inverter then having a plug where you connect a shore supply then DONT do it. One day it will end in tears when the shore supply and inverter are on atthe same time.

If I have got it wrong what you plan to do then I am more than happy to be wrong.

[BEngo]

13 hours ago, John Lewis said:

Cheers Bengo, yes its 16Amp out of RCD..

 

Basically have a junction at this spot, and thought it best to have a socket to switch over to the inverter when off grid.

 

Is a shrouded receptacle like the blue plug that connects boat externally to landline?

To be safe,  to protect your inverter and to pass the BSS you need to be sure that only one thing at a time can be connected to your mains input.

 

So,  mount a surface plug ( eg Screwfix 6490F) somewhere dry but convenient with the pins pointing down if at all possible and connect it to the boat RCD then the boat distribution board using 2.5mm sq flexible cable.  On a flexible  lead from the inverter fit a Screwfix 2264x, or equivalent;  this is a shrouded receptacle.  It has holes for the pins of a plug, but you cannot see or touch any electrically live metal.   On the shore lead, boat end, fit another one.  The shore end of the shore lead will have a plug- Screwfix 3967x or one like it. These have visible pins.

 

There are pictures of all the plugs/sockets on the Screwfix website, but Toolstation and others sell them too.

 

Insert either the shore lead, or the inverter lead into the boat  plug and switch on!

N

15 hours ago, John Lewis said:

ah yes, I get you. might be a proper job.

 

As Jen says maybe the original plug/socket may work.

 

I just thought the socket would be limiting, as it typically has just 16amp fuses I there doesn't it?

 

Where as I have a 32amp I think coming out of RCD..

What about this one - just a changeover switch I think..

https://www.cef.co.uk/catalogue/products/1780798

Plugs and socket works, and is wot I use with a built in genny  but that was not the question you asked?.  If going that way you need shrouded receptacles on the input plugs and the visible pins on the single socket fixed to the boat.  Called a fixed appliance inlet unless you are Screwfix and call it a surface plug.  Item 6490F.  Do not use a surface socket.

 

 

No fuses in a 16A plug, or a 32A for that matter. The mains inlet should be fused at the bollard and have an RCD.  If you are thinking about using 32A you need to look carefully at your existing cabling.  2.5mm squared Arctic blue is not rated for 32A   4mm sq may be, but do check.

 

The switch you link to is good for up to 20A so OK for 16A but  not OK with 32A input. you will also need to find a suitable panel and enclosure to make the connections waterproof, again as your original query.

 

N

 

[ditchcrawler]

Is this all outside, all the talk of waterproof?

[BEngo]

Dunno.  The OP said he wanted the best solution.  As most boat electrics seem to end up in the engine bay where condensation and sometimes  steam can be found, or a in  cupboard  which is largely exposed I looked for IP x4 at least.

I did ask for details of the existing at post 2.

N

 

[John Lewis]

Thanks Bengo, I may just go with the 3 way changeover switch for this.

https://www.cef.co.uk/catalogue/products/1780386-20a-3p-surface-mounting-3-position-changeover-switch-ip65

 

much appreciated.

 

[Slim]

42 minutes ago, John Lewis said:

Thanks Bengo, I may just go with the 3 way changeover switch for this.

https://www.cef.co.uk/catalogue/products/1780386-20a-3p-surface-mounting-3-position-changeover-switch-ip65

 

much appreciated.

 

That's more or less what I've got to switch between f'ward and aft shore power supplies. Mine's rated at 63a ? cos a friend had one going spare. Keep the wiring instructions somewhere safe. Trying to sort out which wire goes where is not easy in a confined space (with a digital meter) I resorted to a temporary 12v supply and a simple 12v circuit tester .