sailorman
Well-Known Member
we have a power pod on the pontoon so an 11m cable is just fine, we do carry 3 other 2.5mm for summer use as often power supplies are sometimes @ a premium & some way off
Shore power cable size
- Thread starter sealegsjim
- Start date
Bru
Well-Known Member
Which reminds me to go and raid the cable crates in the loft and liberate a couple of lengths of 16A for that very purpose! Memo to 'elf ...
David2452
Well-Known Member
With low voltage AC I don't think voltage drop is the main issue, more the ability of the cable to comfortably handle the power being consumed which means 2.5mm2 for 16A
VicS
Well-Known Member
According to this page from Farnell's website 1.5 mm² is rated at 15 amps ( other sources say 16 amps) and 2.5 mm² is rated at 20amps ( other sources say 25 amps)
http://www.farnell.com/datasheets/1661916.pdf
1.5mm² HO7 is however I believe only rated at 13 amps and 2.5mm² HO7 at 16 amps
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Puggy
Well-Known Member
I have two black external cables that can be connected together at 2.5mm and they work just fine. What I have learned is to buy decent quality plugs/sockets as when you load up with the fan heater/Hoover etc and the load gets towards 16amps it is the connectors in the plugs that can get hot and burn out.
David2452
Well-Known Member
That's why I used the phrase "comfortably handle" 1.5mm2 is on the limit, oddly 1.5mm & 2.5mm2 HO7 are both recommended for a max 16a, but that is taking into account their customary usage, which is rough service.
Bru
Well-Known Member
Very much depends on where you look. My usual supplier rates 1.5mm HO7 at a max current of 13A. We would only use 1.5 on single fitting tails and breakout spiders to multiple lamps, on the distro it would be 2.5mm all the way and for rostrum supply, a run of 30 to 50 metres from the distro, e.g the length of the marquee and then some, we had a 50m x 4.0mm cable
lw395
Well-Known Member
The rating of cable is more complicated than that.
Proper design would consider allowable voltage drop, and also max temperature of the insulation.
1.5 sqmm is often rated at 15A, but it depends on the cooling.
A cable outdoors is much better cooled than one sharing a conduit with ten other cables.
A cable strung across the deck will be better cooled than one wound on a drum.
A 1.5 will be well cooled on Windermere at least 9 months of the year.
But it depends on load too, a lot of people push their '16A' supplies with say a fan heater, battery chargers, then put the kettle and toaster on...
Proper design would consider allowable voltage drop, and also max temperature of the insulation.
1.5 sqmm is often rated at 15A, but it depends on the cooling.
A cable outdoors is much better cooled than one sharing a conduit with ten other cables.
A cable strung across the deck will be better cooled than one wound on a drum.
A 1.5 will be well cooled on Windermere at least 9 months of the year.
But it depends on load too, a lot of people push their '16A' supplies with say a fan heater, battery chargers, then put the kettle and toaster on...
Bru
Well-Known Member
You are not wrong, it is more complicated
We perhaps ought to be pedantically specific and strict about saying the maximum current capacity rating as stated by the supplier / manufacturer
And to take that to the next logical step of pedantry then say that the de-rating of the cable is more complex
The pedantic point being that it is never, under any circumstances, acceptable to exceed the maximum rating. From there, you need to look at factors which might require an increase in cable size such as high temperatures, voltage drop over long runs etc.
Oh and a cable wound, or partially wound, on a drum may have it's current rating reduced to as little as 35% of it's rated maximum capacity (4 layers of cable on a ventilated drum). Even simply coiling the surplus length of a cable hand over hand and laying the coil neatly on deck will reduce the current rating (by how much is a matter of God and guesswork but reduce it it will)
In reality, none of this really matters a tinkers, 1.5mm is not beefy enough for a shore power lead, end of. 2.5mm will do the job in normal circumstances, go to 4.0 if it's a very long run.
ANd finally, could you tell me the secret of using a fan heater, battery charger, kettle and toaster at the same time? 'Cos then I could pass it on to Jane and I wouldn;t have to keep resetting the domestic circuit breaker!!!! "Look darling, I don't want to start a row, but can you remember how many freakin' times I've said "turn off the heater before putting the kettle on"?" :/
lw395
Well-Known Member
You are not wrong, it is more complicated
....
ANd finally, could you tell me the secret of using a fan heater, battery charger, kettle and toaster at the same time? 'Cos then I could pass it on to Jane and I wouldn;t have to keep resetting the domestic circuit breaker!!!! "Look darling, I don't want to start a row, but can you remember how many freakin' times I've said "turn off the heater before putting the kettle on"?" :/
I don't know, and if I did, I probably shouldn't publish it, but I've seen it done.
I decided not to ask.
A marina on the Thames.
I've never completely trusted breakers, I like fuses, none of them pesky 'moving' parts!
Hydrozoan
Well-Known Member
You don't - you fit a rotary selector switch so you can have (e.g.) the immersion or the heater, but not both! 'Simples', as that irritating carnivoran says.
Bru
Well-Known Member
With the added advantage that you can replace a fuse with a bent rusty nail. Aha! I think I have found the answer to my question
Disclaimer: The above was a JOKE, a thing of humour and jest. Anybody who takes it seriously fully deserves the nasty surprise they will undoubtedly get!
Bru
Well-Known Member
You don't - you fit a rotary selector switch so you can have (e.g.) the immersion or the heater, but not both! 'Simples', as that irritating carnivoran says.
That's actually a rather good idea. My issue is esxacerbated by the incoming mains consumer unit being a standard garage jobby with a 5A breaker and a 10A breaker. The calorifier immersion coil is on the 5A breaker with the three 13A skts on the 10A breaker so I'm limited to about 2.3kw on the sockets anyway. Upside is that when the dear lady wife does pop the breaker I barely have to move to reset it! I quite like that
Hydrozoan
Well-Known Member
Thank you. I thought it prudent and it let me choose a 1kW immersion without risk of somebody switching on a 2kW heater (and doubtless something else) at the same time. We don't find it at all inconvenient in practice - we select the heater on arrival, and switch to the immersion when warmed up. There are some big cased switches around, but also several neat ones capable of being fitted into a ply panel, thinned out from behind. Mine has the facility to unlock the rear unit from the switch panel, which is convenient when fitting.
lw395
Well-Known Member
With the added advantage that you can replace a fuse with a bent rusty nail. Aha! I think I have found the answer to my question
Disclaimer: The above was a JOKE, a thing of humour and jest. Anybody who takes it seriously fully deserves the nasty surprise they will undoubtedly get!
Anyone with any self respect would at least use a shiny nail......
Bru
Well-Known Member
No, no. noooooo! It's gotta be a RUSTY nail. A shiney nail won't do at all, it won't heat up anywhere near as nicely
And don't you just rue the day when they stopped putting proper tin foil in *** packets? It was SO useful for wrapping around duff fuses ...
Disclaimer as above still applies!
lw395
Well-Known Member
Why has KitKat attracted the swear filter?
prv
Well-Known Member
lw395
Well-Known Member
Because that would allow a total load of 21A.
It's more convenient for the breaker on the boat to trip not the one on the pontoon.
johnphilip
Well-Known Member
+1