What Is The Limit For A 12v Socket

[wooster]

Hi 

 

I'm completely in the dark about electrics ( and most engineering stuff too ! ) and I'm wondering how much power I could draw from the 12V supply on my boat. I will have a 12V TV and probably another powered signal booster for the aerial plugged into this. I have two 12V cig lighter type sockets so should I use a splitter to give me two plugs from one socket or would it be better to use each one for a single item or does it make no difference?

I'm guessing phone/tablet charging etc is nothing for the power draw but if I add in lighting, TV, aerial, to the phone am I getting near to the limit of how much power I can draw ?

Thanks for your patience

[Regulo]

There's no theoretical limit to how much you can draw BUT each socket/circuit will have a fuse, rated to the size and length of cable used. You won't be able to exceed that rating without blowing the fuse. Look on your fuse distribution panel to see what current each circuit can handle, and go by that. Using splitters won't be a problem, as long as the total current draw doesn't exceed the rating of the original socket you're using.

[Vaughan]

To give an idea, I always used to fuse cigar lighter sockets on 15amps DC. A TV (depending on type ) would use about 5 amps and the aerial (at a guess) less than 1 amp.

[wooster]

Thank you. Looks like there would still be some spare capacity after TV and aerial are plugged in using a splitter and I'm guessing phone charging on the other socket won't take up much more. I'm unlikely to plug anything else in at the same time but I was considering using a 12V extension cable on one of the sockets. Would this make the draw more?

[grendel]

Water Rail has 2 12V ockets, one in each cabin, I generally plug a 2 usb adaptor in the forward cabin for charging my phone nad tablet, and in the rear i run a 3 way splitter with USB, from which the laptop and the wifi dongle are plugged in, just make sure your socket is adequately fused and had adequately thick wiring for the current used.

[annv]

Hi Wooster cig sockets if used for cig lighter will have a 20 amp fuse BUT these cig lighter sockets dont always give a good connection as they are loose, as it's your boat why not replace the cig sockets with 5 or 10 amp ROUND 3 pin sockets just for 12volt's and 13 amp square pin for 240v you will then get good contact without the risk of over heating the plug that isn't a good fit, they will also look better as you can fit surface or flush sockets rather then the cig ones that require a deeper space in which to fit them that's why they are userly only fitted to the dash. John

[Oddfellow]

On 14/07/2021 at 00:16, Regulo said:

There's no theoretical limit to how much you can draw BUT each socket/circuit will have a fuse, rated to the size and length of cable used. You won't be able to exceed that rating without blowing the fuse. Look on your fuse distribution panel to see what current each circuit can handle, and go by that. Using splitters won't be a problem, as long as the total current draw doesn't exceed the rating of the original socket you're using.

This should come with a big caveat... The cabling circuit will have a rating that is protected by a fuse (the sole purpose of which is to protect the cabling from overheating and causing a fire). It may not be safe to assume that the fuse that's in the circuit not is the correctly rated fuse as often, people with no idea of the purpose of a fuse will replace with ones of a larger capacity...... 

[grendel]

for an example of what can happen if the lighter socket extension is not correctly rated, I put this here - 

 

[webntweb]

3 hours ago, Oddfellow said:

This should come with a big caveat... The cabling circuit will have a rating that is protected by a fuse (the sole purpose of which is to protect the cabling from overheating and causing a fire). It may not be safe to assume that the fuse that's in the circuit not is the correctly rated fuse as often, people with no idea of the purpose of a fuse will replace with ones of a larger capacity...... 

Or, as in the case of one narrowboat we had a share in, somebody had installed an extra cig socket and managed to reverse the polarity.

[BroadAmbition]

We fitted a surface mounted unit, fuse protected of course. Works well, no issues to date

Griff

 

[wooster]

Thank you for your advice. As I’m pretty clueless about all this I’m having an electrician review my wiring etc soon so I will ask him to install some decent circuits

[ranworthbreeze]

2 hours ago, wooster said:

Thank you for your advice. As I’m pretty clueless about all this I’m having an electrician review my wiring etc soon so I will ask him to install some decent circuits

Hello William you would be better having a marine electrician or a Auto electrician checking out your wiring especially on your DC circuits.

Regards

Alan

 

[wooster]

Hi Alan.
 

Yes the guy is a marine electrician and also a qualified surveyor. He actually did the survey for me and suggested some work to be done so he’s pretty experienced. 
 

he said the wiring was good but e could install an automatic floating bilge switch and could do with more sockets etc