Too much juice on a circuit?

[Two Screwed]

Got a question about wiring in some extras in my cabin on my 95 270 Dancer. This idea all started from a broken bunk/reading light fixture in my aft bunk. In my 270, there is only one 12v cigarette lighter plug below and I would like to expand on that without major re-wiring. The broken light and all other bunk/reading lights are on the "cabin main" switch and since it is rare that I would have all bunk lights (being 6 of them) on at one time, I am thinking of splicing in another 12v fan on that fixture and maybe splicing in another cig plug in the far forward light to power a small 12v 13" flat screen TV. Anyone think this would be an overload of the circuit? I would post this in the electrical forum but a lot of the good help rarely makes it down there. Thanks in advance. DR

 

[magstang1]

You're going to have to figure out the current draw of the things you want on the circuit.

80% of the breaker or fuse rating should be your maximum continuous load.

A 20 amp breaker should have no more than 16 amps on it with everything running at full load.

 

[Old Vet]

remember that wire sizing can come into play as well. wire size and breaker/fuse sizes are determined based upon the loads they are intended to carry. over sized loads on under sized wires can cause wires to overheat....potentially resulting in a fire.

 

[KP49]

Replace the lights with LED and that will put the current draw for them to nearly nothing, a modern LCD 19" TV will draw 3-4 amps (the new 19" I just put in was 3 amps) so I'm sure a 13" will be less. Six 10 watt 12 volt bulbs will take 5 amps. That gives you a 2 amps for 6 LED bulbs which is more than enough. Fans can draw quite a bit so you have to do your shopping there. As mentioned if its protected by a 10 amp fuse/breaker no more than 8 amps total.

 

[magstang1]

remember that wire sizing can come into play as well. wire size and breaker/fuse sizes are determined based upon the loads they are intended to carry. over sized loads on under sized wires can cause wires to overheat....potentially resulting in a fire.

Thats not exactly correct.

Breakers and fuses are sized to the gauge of wire they are connected to. Fuses and breakers protect the wire, not the things (lights, fans...) on the circuit.

When a system is being engineered, the load is approximated and a wire size is selected. An appropriate size fuse or breaker is installed according to the wire size. If individual components require protection, additional inline fuses can be used.

You should never be able to damage the wire by design.

 

[JimG]

To the OP: http://clubsearay.com/showthread.php/59563-Too-much-juice-on-a-circuit Please do not create duplicate threads. Most of us use the "New Posts" feature and will see yours, regardless of the category.

 

[Old Vet]

the load is approximated and a wire size is selected. I thought that was kinda what I said here....."remember that wire sizing can come into play as well. wire size and breaker/fuse sizes are determined based upon the loads they are intended to carry. " My whole point being....tying additional loads onto existing wire isn't always a good idea without knowing wire sizes and load carrying capabilities. Easy for people who don't fully understand electricity.....or at least have a basic working knowledge of it to get themselves into trouble.

 

[Two Screwed]

Sorry about the double post folks....won't happen again. Anyway, I did replace over half of the cabin lights with LED so far (I've just been replacing with LED as the incandescents blow.) Also, If I'm using the TV, there is no need to have any other lights on in that circuit other than perhaps one in the head or one in the aft cabin. I got the plug receptacles wired in today with a 5 amp fuses at the receptacle. I went with a heavier gauge wire when I tied and then only about 2 feet on the run. Also, the plugs on the items themselves have 3amp fuses on them. I left a little bit of wire un-hidden temporarily just to take a feel after I get a chance to run them for a bit just to see if they get warm. In theory, I should be in a safe load limit, although as I type this, I may go ahead and replace the last 3 incandecent bulbs with LED just to be safer. If I don't end up burning my boat to the waterline, this will have made some great added conveniences without the headache of a long wire pull. Thanks for the help in getting me to think through it though folks.

 

[magstang1]

the load is approximated and a wire size is selected. I thought that was kinda what I said here....."remember that wire sizing can come into play as well. wire size and breaker/fuse sizes are determined based upon the loads they are intended to carry. " My whole point being....tying additional loads onto existing wire isn't always a good idea without knowing wire sizes and load carrying capabilities. Easy for people who don't fully understand electricity.....or at least have a basic working knowledge of it to get themselves into trouble.

That wasn't the part I was contesting. I actually agreed with you.

It was the next part about overheating and fires. A properly designed circuit should never be able to get to this point. Assuming Sea Ray did their part in the electrical engineering you should not have to consider wire size.