Waterproof electric power cable........ advice needed!

tokoloshe

tokoloshe

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My mooring is in a secluded bay in the Lake District. I'm not telling you where!

The jetty has no dedicated electrical supply and any cable run from the onshore junction box will spend time in the water.

I can find plenty of information on connectors, RCD's etc. but I am looking for advice on cable specification and source.
 
Personally I'd opt for SWA armoured cable. That's approved for direct burial underground, no considerations of keeping it above groundwater, so ought to be ok if immersed. Also physically protected against the sort of abuse it might get if clipped to an exposed jetty, and if properly protected electrically and using the armour as earth, it should fail safe if damaged.

This is assuming the cable is to be installed, not a portable "shore power" lead. For that, I suppose I'd choose Hi-tuff, which is a fairly rugged kind of flex.

Both are sold by TLC ( http://www.tlc-direct.co.uk/Main_Index/index.html ). Not promising they're the cheapest, but they're who I've used as they have a depot local to me :)

Pete
 
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Steel wire armoured will do the job, you will need to calculate the load and length to get the correct size. Buy two core and earth as you are no longer permitted to use the armoured sheath as an earth, but it must be bonded to the earth wire.
 
BERT T; Buy two core and earth as you are no longer permitted to use the armoured sheath as an earth said:
Hi Bert T

Is there now a specific regulation that bans the armour as a CPC, or is debate still running on steel and equivalent copper size. I seem to remember there was concern about corrosion or the Armour and how it would effect the long term reliability, but it was still allowed by calculation.
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I have found one reference in IEE GN7 that would preclude the use of the armouring as a CPC when SWA cables are used. This is in marinas and the guidance states, "Due to the possibility of corrosion, the galvanised steel armouring of cables must not be used wholly or in part as a circuit protective conductor (CPC) for the floating section of marinas. A separate protective conductor should be used which, when in accordance with Regulation 543.1.2 can be common to several circuits if necessary. The armour must still, however, be connected to protective earth".
 
BERT T said:
I have found one reference in IEE GN7 that would preclude the use of the armouring as a CPC when SWA cables are used. This is in marinas and the guidance states, "Due to the possibility of corrosion, the galvanised steel armouring of cables must not be used wholly or in part as a circuit protective conductor (CPC) for the floating section of marinas. A separate protective conductor should be used which, when in accordance with Regulation 543.1.2 can be common to several circuits if necessary. The armour must still, however, be connected to protective earth".
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Thanks for the reply I've been out of the trade for sometime and no access to guidance notes
 
As others have said armoured cable, we have lots of it running fom the house down the garden to get power to a shed, greenhouse, workshop and exterior power point. It has the normal plastic coating and thus is waterproof.
 
If the junction box has a blue euro socket that you can plug into, just extend in 2.5mm CSA artic blue cable. The building site equivalent is yellow and 110 volt and seems to last quite happily.
 
I hope that this doesn't appear daft, but if you were to contact your local diving company, I feel sure that you'd be able to source a 'cut-off' of approved underwater cable that may even have a PAT test still on it? All diving/ROV companies go through kilometers of this stuff every year. If the locals can't supply, then there are any number of firms in the 'Global Centre of Excellence' that's Aberdeen.
 
Not sure about the regs but pond pumps use a rubber 3 core cable that works happily for long periods under water. Maybe try a water garden/ pond supplier.
 
Domestic rubber coated 3-core is usually waterproof but can have pinholes in it that let the water in. That's why "proper" underwater cables are so much more expensive.
 
I would advise against using SAW cable (not intended for a flexible fixture on a boat) very risky/unsafe and by the sound of your description of a "junction Box" at supply end not possible to connect safely. there is plenty of flexible cable on the market suitable for use as you describe.

My mooring is in a secluded bay in the Lake District. I'm not telling you where!

The jetty has no dedicated electrical supply and any cable run from the onshore junction box will spend time in the water.

I can find plenty of information on connectors, RCD's etc. but I am looking for advice on cable specification and source.[/QUOTE]
 
jackho said:
I would advise against using SAW cable (not intended for a flexible fixture on a boat)
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Agree it shouldn't be used for anything that will move - but the OP never actually said what he wanted it for. I imagined he was running it down a fixed jetty from a junction box on shore, ending in a fixed socket near the end of the jetty.

Pete
 
Thank you peep's.

I am going to run saw armoured cable from the junction box to the jetty, about 30 metres.
The jetty to the boat stern will be serviced by blue arctic cable.

I am currently sourcing an appropriately spec'd RCD which I will locate in my cockpit lazerette.

Many thanks for the sound advice.

David
 
tokoloshe said:
I am going to run saw armoured cable from the junction box to the jetty, about 30 metres.
The jetty to the boat stern will be serviced by blue arctic cable.
Click to expand...

Sounds good. Just to help you in locating the right stuff, it's not SAW, but SWA - "Steel Wire Armoured".

In theory you'll also need to do a volt drop calculation for the length and the amount of current you plan to draw, and calculations for the cross-section of the earthing conductor if you're planning to export the earth. But it's so long since I last did this stuff I'd only get it wrong if I tried to explain - someone else can do it instead :). Or in practice you can just overspec it all by not trying to go for the smallest cable you can get away with, and for the small draw of a boat you're likely to be ok.

Pete
 
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