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riyadhcrew

By riyadhcrew
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MauriceMynah

MauriceMynah

Posted
Posted

Ahhh, Whilst I'm in the company of leccy techy guys, I have some questions. First the basic one.. I know there is a formula for volts watts and amps, but I keep forgetting it. It's something like "Volts = Watts x Amps" Have I got that the right way round?

Second, I would like to see (and understand) a circuit diagram that shows a battery, a light bulb and three switches where each of the switches works entirely independently of the others.

Lastly (for now) What are the requirements for an electric hook-up on a GRP boat with an inboard engine. When my old boat was out of the water for an extended period, I just had a 4 socket extension lead set up, hot glued to a bulkhead. When she went back into the water, I was told to take it off or the boat would fail its BSS. Why?

Oh and lastly lastly, if I have a battery charger permanently attached to a battery, is anything happening when it isn't plugged in?

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MBA Marine

MBA Marine

Posted
Posted
5 minutes ago, MauriceMynah said:

Ahhh, Whilst I'm in the company of leccy techy guys, I have some questions. First the basic one.. I know there is a formula for volts watts and amps, but I keep forgetting it. It's something like "Volts = Watts x Amps" Have I got that the right way round?

Do you meen Watts/volts=Amps?

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Regulo

Regulo

Posted
Posted

Oh, MM, you really are asking for trouble now. I predict that within one page of replies, we'll be into a big, BIG discussion on RCD devices, galvanic isolators, Higgs-Boson particles and whether Santa Claus exists (of course he does, children). Why do you wind them all up?

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Bound2Please

Bound2Please

Posted
Posted
17 minutes ago, MauriceMynah said:

 I would like to see (and understand) a circuit diagram that shows a battery, a light bulb and three switches where each of the switches works entirely independently of the others.

John why would you want to see a circuit diagram of three switches and a battery connected to a bulb for..... the bulb would surely be planted on the bankside some where. Where as on your boat maybe you wish to light a lamp from three different power source's?

Charlie

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TheQ

TheQ

Posted
Posted

MM, This could go on as someone says for a long time so, first download the BSS guide

 www.boatsafetyscheme.org (type "guide" in the search box it'll find the PDF)

Then have a read of the relevant section, then come back with questions after.... it might save the questions wandering off into answers you don't want.

 

or Watts = Volts X Amps

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Jonathan

Jonathan

Posted
Posted
51 minutes ago, MauriceMynah said:

Second, I would like to see (and understand) a circuit diagram that shows a battery, a light bulb and three switches where each of the switches works entirely independently of the others.

MM,

Presumably, you understand the case where two switches are used to control one light.  This uses two-way switches where the common terminal of the switch is connected to one "live" or the other "live" terminal depending on the switch position.  If you connect one side of the battery to the bulb and the other side to one switches common terminal, the other side of the bulb is connected to the other switch common terminal then connect the "live one" of one switch to the "live one" of the other, and similarly "live two" to "live two". Now the light will be controlled by either switch.  If you want to use a third switch then you need a different sort of switch!  You can get "crossover" switches which have two input terminals and two output terminals.  In one switch position the first input terminal is connected to the first output terminal and the second input to the second output terminal (straight-through); in the other switch position the first input is connected to the second output, and the second input to the first output (crossover).  If you put this switch between the "live one" to "live one" and "live two" to "live two" connections of the  two-switch circuit then you have one light controlled by any one of three switches.

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MauriceMynah

MauriceMynah

Posted
Posted

Ok, Yes it's amps I'm normally trying to find. I have a 12 volt system powering a 12 watt LED so I'm trying to find out the best cable to use. (that was just an example of one job I'm needing to do)

Thanks Jonathan, I more or less understood that but I'd like to see the circuit diagram to make sure.

Not quite Charlie... I would like the LEDs ( :) ) powered from one power source but controlled by three switches.

There is also (at the moment) a non boat application. We have a car port and I want to put some lights on it. "Simples" one might say. I want the lights to come on when it gets dark so I need a light sensitive switch. However, I don't want them to stay on all night so there needs to be a time switch in the system. Needless to say that should someone approach the car port in the wee small hours whilst it's still dark but the time switch has turned the lights off, a proximity switch needs to turn them back on. finally it might be handy if I had a traditional switch so I could turn them on and off in the normal way, plus a final switch overriding the whole shooting match to turn it off!

All seems logical to me!

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Regulo

Regulo

Posted
Posted

HaHaHa. Told you!

Best solution for your carport is a 2-level security light. It comes on at dusk at a low power, but increases to full brightness if someone approaches. Uses very low current at it's low level.

Or there are security light switches - turn on at dusk off at a preset number of hours later.

How complicated do you want it!

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riyadhcrew

riyadhcrew

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MM,

With regards to your car port, as I see it, you need not care if it is dark or light, all you want is the lights to come on if anybody needs them to (proximity). You can put a normal light switch between the power supply and the proximity sensor / light and you have your simple system. It's either on or off.

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LondonRascal

LondonRascal

Posted
Posted

Firstly John, one of the things you need to consider when fitting 240v on a boat is something called Galvanic Corrosion - which though less so in GRP boats (compared to say Steel boat) is still relevant.  I found this video which gives a good idea of what it is and what it does.

As to installing 'Shore Power' to your boat, see the PDF that I have attached to this post which gives a good overview. Like Varnishing, many people have their way of doing things - some by the book, others over and above the book to be extra safe - but don't do throw away the book and take risks because this is not 12v after all.

I'll leave others to help with your light switches and car port :)

 

Install Shore Power.pdf

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