Wiring a sailaway

[jddevel]

1 hour ago, NMEA said:

not if you were using conduit wire, it's the sheath that makes the difference

Are you referring to the cabling used in houses please?

[Chewbacka]

22 minutes ago, jddevel said:

Are you referring to the cabling used in houses please?

House wiring (as in twin & earth) is solid core and does not comply with the regs.  Arctic flex has individually insulated conductors contained within an outer insulating sheath which is what he is referring to. 

Added - it's called Arctic  as it has good low temperature performance, and flex as it is a proper flexible cable and often used for outside extension leads.

Added again - as an example - http://www.toolstation.com/shop/p24117 -  blue by convention is used for 230v AC and yellow for 110v AC.

Edited May 12, 2017 by Chewbacka

[NMEA]

1 hour ago, jddevel said:

Are you referring to the cabling used in houses please?

No, conduit wire is single core but on a boat would still be multi strand. 

[Chewbacka]

20 minutes ago, NMEA said:

No, conduit wire is single core but on a boat would still be multi strand. 

Boats will often use what is known as Tri-rated conduit cable.  Such as this https://www.cse-distributors.co.uk/cable/high-temperature-cable/tri-rated-cable/

Added - I know you (NMEA) know this, but it was to help the questioner.  Sorry if not clear first time.

Edited May 12, 2017 by Chewbacka

[jddevel]

1 hour ago, Chewbacka said:

House wiring (as in twin & earth) is solid core and does not comply with the regs.

This what I understood and have used artic blue. I didn`t understand the expression "conduit wire" but understand multi stranded single core. It`s such lack of understanding on my part which is why I believe it makes more sense to have this part of the fit-out dealt with by a professional.

[Chewbacka]

1 minute ago, jddevel said:

This what I understood and have used artic blue. I didn`t understand the expression "conduit wire" but understand multi stranded single core. It`s such lack of understanding on my part which is why I believe it makes more sense to have this part of the fit-out dealt with by a professional.

12v wiring is fairly logical and simple, but it can get confusing because of the terminology, but ask on here and it can all be explained.  Even reading the regs is not so difficult once you get used to the structure of the English used and the specific meaning of the terms used.

[nicknorman]

Just to reinforce what's been said in this thread, there is no need to seperate mains 3 core flex (e.g. Arctic etc) from 12v wiring, either in relation to the BSS or the relevant ISO (if compliance with the RCD is required).

[jddevel]

12 hours ago, Chewbacka said:

House wiring (as in twin & earth) is solid core and does not comply with the regs.

This what I understood and have used artic blue. I didn`t understand the

Duplicate submission my apologies started typing yesterday-interrupted and then thought I`d deleted it and started again

[jddevel]

So advice what would you suggest in this instance. 3000 watt Victron inverter  from this I`ve currently run a 2.5mm artic blue in three separate cables

1) To 240volt to single socket on to washing machine isolator on to single socket.

2) To 240 volt  double socket

3) To 240 volt isolator leading to fridge freezer and gas cooker ignition on to single socket

 Apart from the double socket on the galley worktop to serve say microwave maybe kettle the other single sockets are for say TV  laptop etc. althought there are other 12v sockets for TV, laptop.

Do I really need those 3 separate circuits to be in ring mains =personally I would have thought not nor would I have to increase their size. "just in case"

What does the forum think would be good practice.

[Chewbacka]

Firstly to comply with the BSS all your sockets should be run from some form of consumer unit, with each circuit having a mcb or fuse.  It does not matter - within reason - how many sockets you have as the mcb in the consumer unit will protect the cable, and secondly, the inverter - unless it is a posh one that can boost mains shore power - has an output limit of 3kW which 2.5mm2 cable can handle.  You will overload the inverter - which will shut down - before you overload the cable.

Same with shore power if your system is designed for 16A supply, as again the 2.5mm2 cable will cope with 16A and the supply mcb will overload and trip before the cable.  I have never seen a shore power cable on cruising inland waterways craft bigger than 2.5mm2, but for a residential moored boat, it may well have 32A capacity or bigger.

In summary the cable has to be able to cope with the supply capability as well as the load.  If the supply to the cable is limited - either by the size of the inverter, shore power supply or the circuit breaker for the cable, then the cable only need to have that capacity.  This is why most people have simple radial circuits on boats, though if you have a very long cable you may want to go to a ring to reduce volt drop, but I am not aware of any requirement to do so.  Let's see what others think.

[nicknorman]

12 minutes ago, jddevel said:

So advice what would you suggest in this instance. 3000 watt Victron inverter  from this I`ve currently run a 2.5mm artic blue in three separate cables

1) To 240volt to single socket on to washing machine isolator on to single socket.

2) To 240 volt  double socket

3) To 240 volt isolator leading to fridge freezer and gas cooker ignition on to single socket

 Apart from the double socket on the galley worktop to serve say microwave maybe kettle the other single sockets are for say TV  laptop etc. althought there are other 12v sockets for TV, laptop.

Do I really need those 3 separate circuits to be in ring mains =personally I would have thought not nor would I have to increase their size. "just in case"

What does the forum think would be good practice.

No need for ring mains circuits if you are limiting the whole thing to 16A (normal max shore inlet and around 3500w). But of course you need MCBs or RCBOs rated appropriately for the cable. On our boat we just have one 16A RCBO near the output from the Combi and all the sockets are fed from that via a single 2.5mm 3-core arctic cable, just daisy chained. If you have an immersion heater you might want a seperate feed and breaker for that from the shore side of the Combi bu we went for the whole lot connected after the Combi, which allows the immersion to be run from the Combi if we so wish (engine running, hopefully).

[jddevel]

Thank you Chewbacka and Nicknorman. You`ve confirmed yet again my own view and that the "engineer" since dispensed with- who suggested all the upgrades. To confirm I WILL be using a traditional domestic consumer unit for the 240 service from the inverter with the relevant RCBOs ( as they I believe offer better protection although more expensive) with each circuit daisy chained/radial.

[WotEver]

It's worth noting that ring wiring for mains is an almost exclusively British thing, introduced at the back end of WW2. Many folk will say that it was introduced due to copper shortages and enabling smaller cables to be used however there is no evidence to support this and it requires a greater length of cable anyway. For a boat it offers no advantages. 

[Paul C]

Slightly greater length - but with half the thickness (half the CSA).

I can't think of a single occurrence where you'd use "conduit cable" on a boat - each item, effectively, 'wants' all 3 wires connected to it, be it a socket, fridge, etc - but I'm happy to be enlightened.

[WotEver]

4 hours ago, Paul C said:

Slightly greater length - but with half the thickness (half the CSA)

Not as originally written in 1942. It was recommended that the cable should be able to handle 2/3 of the current of the circuit. So only slightly smaller CSA. 

[MtB]

7 hours ago, Paul C said:

Slightly greater length - but with half the thickness (half the CSA).

I can't think of a single occurrence where you'd use "conduit cable" on a boat - each item, effectively, 'wants' all 3 wires connected to it, be it a socket, fridge, etc - but I'm happy to be enlightened.

 

Surely half the 'thickness' (by which I guess you mean diameter) gives one quarter the CSA.

[NMEA]

14 hours ago, Paul C said:

Slightly greater length - but with half the thickness (half the CSA).

I can't think of a single occurrence where you'd use "conduit cable" on a boat - each item, effectively, 'wants' all 3 wires connected to it, be it a socket, fridge, etc - but I'm happy to be enlightened.

You are assuming low voltage AC, "conduit wire" or single core multi strand is more often used in extra low voltage DC installations, particularly switches, where the load is one of  closely grouped set and has its return via a close by bus bar and single heavy cable back to negative serving a number of devices. In fact this is how I often lay out certain applications on new fit outs and refits. This is particularly useful on nav stations which are rarely found on narowboats but there are many instances where it is useful.

[adrianh]

You could try Semington dock, K & A if you want professional help, would meet your 4 hour travel limit easily.