Wire size

[DavidGrieves]

Hi

I'm helping a friend install shore power. Do we need to use 2.5mm (flex) as we would in a domestic installation (2.5mm T&E). Or can we use 1.5mm flex?

1.5mm is good for 15 amps or 3600 watts. The boat is 28ft we are only fitting 2 or 3 sockets and a battery charger. No immersion heater. I can't see him exceeding 3600 watts. Most of the shore power cables I see around the marina don't appear to be bigger that 1.5mm

Before we get shot down, we are fitting a garage type consumer unit with a double pole isolator, MCB's and RCD's and galvanic isolation.

Thanks

David

 

[nigelmercier]

How long is the lead?

My internal wiring, including the inlet, is 1.5mm² which I'm not terribly happy about. But on the other hand I don't use any high current gear for more than a couple of minutes. If I had an electric fire I would upgrade it.

Not that it makes much difference, but a shore power socket is normally 16A, so a max of 3,680W.

 

[prv]

Have a play with a volt-drop calculator (eg http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html ). Looks to me like 1.5mm is ok up to 25 metres at 3600w, provided you're happy with 5% voltage drop. (I picked Hituf cable as being the most similar to shore power flex, not sure how much difference it makes.)

I chose to calculate mine based on a draw of 16 amps, that being the maximum available through the standard blue ceeform connector. I also have (potentially) a much longer cable - I carry two 10m lengths in the cockpit locker and the same again in deep stowage, so can reach a socket 40m away if necessary. So I definitely need the 2.5mm!

Pete

 

[VicS]

Hi

I'm helping a friend install shore power. Do we need to use 2.5mm (flex) as we would in a domestic installation (2.5mm T&E). Or can we use 1.5mm flex?

1.5mm is good for 15 amps or 3600 watts. The boat is 28ft we are only fitting 2 or 3 sockets and a battery charger. No immersion heater. I can't see him exceeding 3600 watts. Most of the shore power cables I see around the marina don't appear to be bigger that 1.5mm

Before we get shot down, we are fitting a garage type consumer unit with a double pole isolator, MCB's and RCD's and galvanic isolation.

Thanks

David

Presumably your garage consumer unit has a 16amp mcb and a 6 amp mcb and you will be wiring the two sockets to the 16 amp mcb. That will limit the current to 16amps so no need for wiring heavier that that for the internal wiring.

A domestic ring main is fed from a 32 amp mcb ITYWF

You will use "arctic" cable for the shorepower lead for flexibility in cold conditions ? 1.5 mm² should be Ok if fully flaked out but not if used partly coiled or perhaps if so long that volts drop becomes significant

 

[David2452]

The difference in cost between 2.5 & 1.5mm2 Arctic is so small that regardeless of any volt drop the extra physical robustness of 2.5 is worth having. If its long enough for you, a 14m shore power lead from Screwfis with standard 2 pin and pe round plug and socket and Actic cable is 23.99 in 1.5mm & 28.99 in 2.5mm. I only keep 2.5mm & 4mm drums now and don't use 1.5mm at all except for lighting circuits.

 

[Storyline]

Storyline was professionally wired and they used 2.5mm flex. It is easy to use more electricity than you think. In our case it is fan heater in saloon and hairdryer in aft cabin. OK it is not for long but it is nice to know the wiring can take it. I also always use the fan heater on the 1kw setting.