12v fuses and plugs

[Boaty McBoaty]

Hi. I’ve just wired up a clipsal 2 pin plug on a table lamp to plug into a 12v socket on board our NB. All standard 12v parts I think. But the plug only has a L and N and doesn’t include a fuse holder. Is it normal to just have no fuse on these plugs and rely on whatever main circuit fuse that there is on the 12v socket / circuit?? It’s powering a table lamp with LED 10-30VDC bulb. Thanks. 

[WotEver]

58 minutes ago, Boaty McBoaty said:

Is it normal to just have no fuse on these plugs and rely on whatever main circuit fuse that there is on the 12v socket / circuit??

Yup. 
 

The fuse on the Fuseboard protects the cable that feeds the socket, so if you did anything dumb like short out the cables in the plug then the fuse would blow and no harm would befall the cabling. 
 

The reason that you’re used to 13A plugs having fuses in them is that the mains circuit in a building is generally wired as a ring and fused at 32A, so individual items need to be fused at well below that (32A at 230V is nearly 7,500Watts). Plugs in the rest of the world aren’t fused, it’s a particularly UK thing. 

[Boaty McBoaty]

Great. Appreciate your help......lamp now on thanks so will be able to see the dominoes tonight! ?

[system 4-50]

17 hours ago, WotEver said:

it’s a particularly UK thing. 

Having wandered around a USA house trying to find which socket was a high amp socket, I reckon its brilliant.

[WotEver]

6 minutes ago, system 4-50 said:

Having wandered around a USA house trying to find which socket was a high amp socket, I reckon its brilliant.

Arguably the best in the world. But there are plenty who would enjoy the argument

 

British plugs are also unique for being the only ones to lay on their backs whenever you’re walking around barefoot...

[Sea Dog]

Some time ago in the navy, most kit was 115v 60hz but they used to have 230v kit occasionally where unavoidable. They fitted this kit with a plug similar to the standard 3 square pin plug tops, but with one conductor turned through 90 degrees. This thwarted theiving sailors from having it away with plug tops he could use at home. Of course, the cost was astronomical and it would have been cheaper to give all sailors free plugs. Eventually, someone saw sense.

 

115v 60hz is still the standard for most onboard equipment for safety reasons, but 230v domestic circuits also now feature widely - with standard UK 3 pin plugs. I feel sure @mrsmelly would have jumped at the opportunity to take his hairdryer to sea... 

 

[ditchcrawler]

14 minutes ago, Sea Dog said:

Some time ago in the navy, most kit was 115v 60hz but they used to have 230v kit occasionally where unavoidable. They fitted this kit with a plug similar to the standard 3 square pin plug tops, but with one conductor turned through 90 degrees. This thwarted theiving sailors from having it away with plug tops he could use at home. Of course, the cost was astronomical and it would have been cheaper to give all sailors free plugs. Eventually, someone saw sense.

 

 

When I worked in a factory we just painted them a reddy brown colour with jointing compound to stop people nicking them . I understand that the Navy use to twist all there rope in the opposite direction so they could identify it

[mrsmelly]

2 hours ago, Sea Dog said:

Some time ago in the navy, most kit was 115v 60hz but they used to have 230v kit occasionally where unavoidable. They fitted this kit with a plug similar to the standard 3 square pin plug tops, but with one conductor turned through 90 degrees. This thwarted theiving sailors from having it away with plug tops he could use at home. Of course, the cost was astronomical and it would have been cheaper to give all sailors free plugs. Eventually, someone saw sense.

 

115v 60hz is still the standard for most onboard equipment for safety reasons, but 230v domestic circuits also now feature widely - with standard UK 3 pin plugs. I feel sure @mrsmelly would have jumped at the opportunity to take his hairdryer to sea... 

 

[Murflynn]

14 hours ago, WotEver said:

 

British plugs are also unique for being the only ones to lay on their backs whenever you’re walking around barefoot...

they are designed that way so you can find a dropped plug with your feet in the dark.

[Jen-in-Wellies]

1 hour ago, Murflynn said:

they are designed that way so you can find a dropped plug with your feet in the dark.

A triumph of world beating British engineering! 

[Iain_S]

15 hours ago, ditchcrawler said:

(snip) . I understand that the Navy use to twist all there rope in the opposite direction so they could identify it

  The navy, along with the merchant fleet, used cable laid rope, usually when a thick rope was required. 3 or 4 normal ropes were laid together with a left handed twist to form a cable. Because of the left hand lay, cables have to be coiled anti clockwise rather than clockwise. Nowadays, plaited ropes tend to be used, which can be coiled in either diection.

[cuthound]

18 hours ago, Sea Dog said:

Some time ago in the navy, most kit was 115v 60hz but they used to have 230v kit occasionally where unavoidable. They fitted this kit with a plug similar to the standard 3 square pin plug tops, but with one conductor turned through 90 degrees. This thwarted theiving sailors from having it away with plug tops he could use at home. Of course, the cost was astronomical and it would have been cheaper to give all sailors free plugs. Eventually, someone saw sense.

 

115v 60hz is still the standard for most onboard equipment for safety reasons, but 230v domestic circuits also now feature widely - with standard UK 3 pin plugs. I feel sure @mrsmelly would have jumped at the opportunity to take his hairdryer to sea... 

 

 

We did the same with circuits supplied from an Uniterruptible Power Supply in telephone exchanges and data centres, to prevent Mrs Mopp plugging her hoover in and overloading the UPS, this bringing down the critical supplies. ?

[WotEver]

33 minutes ago, cuthound said:

 

We did the same with circuits supplied from an Uniterruptible Power Supply in telephone exchanges and data centres, to prevent Mrs Mopp plugging her hoover in and overloading the UPS, this bringing down the critical supplies. ?

You can buy a whole range of non-standard 13A plugs and sockets: https://www.flameport.com/electric_museum/plugs_13A_non_standard/index.cs4

This one is fun: https://www.flameport.com/electric_museum/plugs_13A_non_standard/walsall_gauge_socket_plug_13A.cs4

[Detling]

23 hours ago, ditchcrawler said:

 I understand that the Navy use to twist all there rope in the opposite direction so they could identify it

Not totally correct, rope up to about 1 inch diameter is normal clockwise lay, thicker ropes for anchor's,  shrouds etc were cable lay (opposite way) which used 3 or 4 ropes twisted together to make a fatter one. (You can still see them do this at Chatham dockyard) each royal dockyard had its own ropewalk and each used to lay a coloured strand into every rope known as a rogue's yarn. Each ropewalk used it's own colour, Chatham was red, Portsmouth was yellow, I don't know any others but there were more naval ropewalks. 

[wakey_wake]

Suddenly curious:

 

On 15/08/2020 at 18:17, Sea Dog said:

115v 60hz is still the standard for most onboard equipment for safety reasons,

 

It had not occurred to me to run 115V mains. Does anybody, on canal boats? Then with what kind of, a NEMA 5-15?

 

I tend to think that the places where the mains reaches should all be staying dry, but ? ?️ water and leccy are both tricky ones for finding their way where they aren't welcome...  but I don't think I would want two inverters and four+ voltages kicking around on my boat.

[Alan de Enfield]

18 minutes ago, wakey_wake said:

It had not occurred to me to run 115V mains. Does anybody, on canal boats? Then with what kind of, a NEMA 5-15?

 

 

CONFUSION.

 

Sea Dogs post relates to 'big Navy' type ships, and USA 'mains' electric (120v AC at 60HZ)

 

Narrowboats are 12v or 230v 50Hz via an inverter (which takes 12v DC from the batteries and changes it to 230v AC)

[wakey_wake]

27 minutes ago, Alan de Enfield said:

CONFUSION.

 

Sea Dogs post relates to 'big Navy' type ships, and USA 'mains' electric (120v AC at 60HZ)

 

Narrowboats are 12v or 230v 50Hz via an inverter (which takes 12v DC from the batteries and changes it to 230v AC)

 

Not me not this time ? but it could look a lot like it... I know that I've never seen 115V on a narrowboat. I'm wondering if anyone ever did.

 

110V is in use in the UK, e.g. these ugly great things, https://www.everydayweldingsupplies.com/draper-1kva-230v-to-110v-portable-site-transformer on building sites. I believe it is for the safety aspect of 110V power tools & light strings.

I would guess that 110 ~ 120V is within tolerance for most things, but its always best to check the label.

 

Lots of power bricks take 90~240V and US equipment would be happy with it, so it is an option. I have no 110V kit and unlikely to buy any. I wouldn't do it to my boat, nor suggest anyone else should.

 

(What I actually woke the browser for is the perennial question of what to use for 12V sockets. I'm reading the old posts and making a little list...)

[Sea Dog]

11 hours ago, wakey_wake said:

It had not occurred to me to run 115V mains. Does anybody, on canal boats?

It could be done of course - 115v inverters are commonplace for other markets - but 115v appliances are not the norm in the UK and shore supplies are invariably 230v. So, whilst it is safer, you are swimming against the tide. Plus, if you halve the voltage, you double the current for a given power output, and this would entail thicker cables and precipitate a rewire. Use 230v and be aware of, and mitigate for, the dangers would still be my route.

 

Even the Navy have increased the domestic 230v supplies on board now - hairdryers and curling tongs, I suspect, which has probably increased even more since we sent women to sea...

 

[ditchcrawler]

11 hours ago, Alan de Enfield said:

 

 

CONFUSION.

 

Sea Dogs post relates to 'big Navy' type ships, and USA 'mains' electric (120v AC at 60HZ)

 

Narrowboats are 12v or 230v 50Hz via an inverter (which takes 12v DC from the batteries and changes it to 230v AC)

who also use 230 volts between phases

[Alan de Enfield]

Just now, ditchcrawler said:

who also use 230 volts between phases

 

 

Indeed - at home we have gone the 'other way' and have a 415v supply and are splitting phases.

[cuthound]

13 hours ago, wakey_wake said:

Suddenly curious:

 

 

It had not occurred to me to run 115V mains. Does anybody, on canal boats? Then with what kind of, a NEMA 5-15?

 

I tend to think that the places where the mains reaches should all be staying dry, but ? ?️ water and leccy are both tricky ones for finding their way where they aren't welcome...  but I don't think I would want two inverters and four+ voltages kicking around on my boat.

 

If you have more than one inverter on board and their outputs are not synchronized together, then you potentially have 400 volts plus across them.

 

For this reason, if you have more than inverter on board, the sockets powered from one must be 2 metres (more than an armstretch) away from another.

Edited March 13, 2021 by cuthound
Phat phingers

[ditchcrawler]

1 minute ago, cuthound said:

 

If you have more than one inverter on board and their outputs are not synchronized together, then you potentially have 400 volts plus across them.

 

For this reason, if you have more thsn inverter on board, the sockets powered from one must be 2 metres (more thsn an armstretch) away from another.

I am glad someone else has pointed this out, I see so many posts where people say I will have a small inverter for the TV and charging laptops and a big one for when I want to use the washing machine etc.

[wakey_wake]

1 hour ago, cuthound said:

If you have more than one inverter on board and their outputs are not synchronized together, then you potentially have 400 volts plus across them.

 

1 hour ago, ditchcrawler said:

I am glad someone else has pointed this out, I see so many posts where people say I will have a small inverter for the TV and charging laptops and a big one for when I want to use the washing machine etc.

 

Yes, I'm capable of understanding and predicting this hazard but I had not done. ?

[ditchcrawler]

27 minutes ago, wakey_wake said:

 

 

Yes, I'm capable of understanding and predicting this hazard but I had not done. ?

I wasn't getting at you, but its a point that comes up a lot on Facebook groups and if you don't have an understanding of AC and Phases its not something that is easy to grasp 

[ditchcrawler]

On 15/08/2020 at 17:40, system 4-50 said:

Having wandered around a USA house trying to find which socket was a high amp socket, I reckon its brilliant.

I can remember houses haven 2, 5 and 15 amp unfused round pin plugs also people connecting the flat iron to a BC plug so it could be plugged into the twin adaptor in the kitchen light above the table. The good old days or rewireable fuses and if it blew you just put 3 strands in next time.

14 hours ago, wakey_wake said:

 

Not me not this time ? but it could look a lot like it... I know that I've never seen 115V on a narrowboat. I'm wondering if anyone ever did.

 

110V is in use in the UK, e.g. these ugly great things, https://www.everydayweldingsupplies.com/draper-1kva-230v-to-110v-portable-site-transformer on building sites. I believe it is for the safety aspect of 110V power tools & light strings.

I would guess that 110 ~ 120V is within tolerance for most things, but its always best to check the label.

 

Lots of power bricks take 90~240V and US equipment would be happy with it, so it is an option. I have no 110V kit and unlikely to buy any. I wouldn't do it to my boat, nor suggest anyone else should.

 

(What I actually woke the browser for is the perennial question of what to use for 12V sockets. I'm reading the old posts and making a little list...)

If you ever use Wigan Dry Dock it only has a 110 volt  supply so you can't use your DIY tools of plug in for shore power.