Shore Power Specifications 16A, 32A Round Pins/Holes, Flat Pins/Slots

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Hi,

I am trying to understand shore power standards for my existing system. My shore power cable has the 3 x round pins/holes but the shore power inlet has the 3 x flat pins (slightly concave, with a very shallow 'L' profile). I use a cross over between the inlet and the cable top connect the system up.

The boat is wired for 240V mains via a consumer unit to a ring main (6 x 13A outlets), immersion heater, fridge and battery charger (24V, 30A, 600W). There is a galvanic isolator wired up as well.

I understand that shore power comes in 16A or 32A sizes. I have no idea what I have but the shore power inlet is scorched. Could the sterling charger draw up to 30A from the mains and could this be the reason for scorching on the inlet if I have a 16A rated system (assuming the wire is terminated OK)?

I will replace the inlet this winter and wish to order one soon. I have a hankering that the flat pins maybe USA specification but I am not sure.

All advice appreciated. Thanks,

BlowingOldBoots
 
BlowingOldBoots said:
Hi,

Could the sterling charger draw up to 30A from the mains and could this be the reason for scorching on the inlet if I have a 16A rated system (assuming the wire is terminated OK)? BlowingOldBoots
Click to expand...

If the power post is 16a it will (should) have both RCD and and apropriately rated MCB which would trip, also the Sterling is presumably cabled up through an apropriate MCB in your consumer unit so not if all is well in that department as it would trip the MCB in the CU.
 
The three flat L-shaped pins in a circle is the US standard, though it may also be rated for 240v I don't know. Because they have weedier volts they have to pack in more amps to make up for it, so I'm surprised you managed to overload one of their sockets.

Pete
 
My guess is that the inlet has been overloaded ... perhaps there is no circuit breaker, or an incorrectly rated one, on the incoming shorepower supply

decide on the maximum power you will want to draw based on the rating of the ring main circuit breaker + the immersion heater + fridge + charger.

The fridge wont be a lot, the immersion heater could be 13 amps if its a domestic type otherwise less , The battery charger should be under 5 amps. (24 volts at 30 amps equates to 3 amps at 240 volts and 600watts is only 2.5 amps at 240 volts )

Make sure you inlet cable and the shorepower lead are rated to carry this combined load. Select the appropriate plug and socket for the shorepower connections and be sure there is a correctly rated circuit breaker of an appropriate type between the input connector and the consumer unit.

Professional help might be wise!
 
Another thought - I've never handled one of these US plugs in the flesh, but I've read that cheap ones can be prone to poor connection. Perhaps the load was reasonable but the plug wasn't quite seated properly?

Personally I'd swap it for a European standard ceeform (the ubiquitous round blue one). They're not expensive, especially from caravan suppliers.

Pete
 
I have seen many scorched 13A plugs and sockets, and in every case it has been a bad connection between wire and pin inside the plug. That's the pinch point in the system. The pins and sockets have a significantly greater cross sectional area than the wires leading to them and are therefore unlikely to get hot because if the current is that high the who wire will be smouldering gently.

Have the plug apart and look inside. I bet you find something nasty.
 
JumbleDuck said:
I have seen many scorched 13A plugs and sockets, and in every case it has been a bad connection between wire and pin inside the plug. That's the pinch point in the system. The pins and sockets have a significantly greater cross sectional area than the wires leading to them and are therefore unlikely to get hot because if the current is that high the who wire will be smouldering gently.

Have the plug apart and look inside. I bet you find something nasty.
Click to expand...

Poor connection between the pins and the contacts in the sockets, esp in a corrosive environment, can cause it too.
 
Your original inlet connector sounds like its a Marinco. Details here ...

http://www.marinco.com

The domestic voltage in the US is 110v, which means over twice the current for the same power, so they should be good for 240v, but you will need to check the rating.

As mentioned already its likely loose connection clamps or water contamination, or a bit of both. Stranded wire does tend to flay and loosen over time, I prefer to solder the ends, or crimp a small copper ferrule.
 
Okay, thanks for the help. The consumer unit has the RCD which switches off all the power and has the 'push to test' button on it. The circuits all have MCBs but the Sterling is plugged into a ring main plug. There are a couple of spare bays in the consumer unit, so I'll have the Sterling Unit rewired to this with an appropriate MCB.

The shore power inlet has always been a faff to use. It's basically just a stab in fit and an external collar which locks the plug in place with a 1/8th turn. The plug has some plastic radial fins which I assume are to make a seal, these are quite a tight fit. It is possible that the shore power plug has been twisted in an attempt to lock it in place, instead of rotating the lock ring - in fact that is likely, so I am sure there will be damaged wires.

I'll check out the amperage of all the consumers plus some additional stuff and then buy a quality shore power inlet unit to the European spec.

I will pay someone to do this and check the whole system over anyway.

Thanks for the help,

BlowingUpOldBoots (-;
 
BlowingOldBoots said:
Hi,

I am trying to understand shore power standards for my existing system. My shore power cable has the 3 x round pins/holes but the shore power inlet has the 3 x flat pins (slightly concave, with a very shallow 'L' profile). I use a cross over between the inlet and the cable top connect the system up.

The boat is wired for 240V mains via a consumer unit to a ring main (6 x 13A outlets), immersion heater, fridge and battery charger (24V, 30A, 600W). There is a galvanic isolator wired up as well.

I understand that shore power comes in 16A or 32A sizes. I have no idea what I have but the shore power inlet is scorched. Could the sterling charger draw up to 30A from the mains and could this be the reason for scorching on the inlet if I have a 16A rated system (assuming the wire is terminated OK)?

I will replace the inlet this winter and wish to order one soon. I have a hankering that the flat pins maybe USA specification but I am not sure.

All advice appreciated. Thanks,

BlowingOldBoots
Click to expand...



Hubbell do a range of shore power connections which are fine and used almost exclusively in the USA . Beware though as they do some suiteable for 125V and some for 240 Volts. Usually they are marked to show which is which. A similar but smaller plug is used for things like washing machines and cookers which could be the type the BBC do not like. The Shore power connectors are horrendously expensive!


http://www.hubbell-wiring.com/marine/


A search on Hubbell here will bring up previous threads including how the plugs should be wired.
 
pvb said:
But if they're [Hubbell plugs] extensively used in the USA, where I'd hazard a guess that shorepower demands on average are higher than in the UK, why do you think they're nasty?
Click to expand...

Hubbell plugs are of course just a brand name for NEMA plugs, which are used throughout the USA, my fault for using the brand name. The pins are much thinner, although the L-shaped ones have a bit more meat on them. AFAIK they were banned by the BBC because the earth pin could break off, or bend in such a way that it could touch the live pin.

I have nothing against them for 2-pin low current devices, in fact I have such sockets on my workbench in 230V and 110V flavours.
 
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