anyone know how to calculate the total current on a given circuit?

I've got 5 tubs set up with 11" flexwatt heat tape, each one is 1ft in length.

the instructions say that each foot uses 20 watts , but wanted to add some more stuff on another power bar for my display tank using the same outlet. I'd like to work out how much current its going to be drawing so I don't keep tripping the breaker, or cause a fire .

In the display tank I was planning to put in a fan , light, and a water pump for a waterfall.
I want to have two power bars on one outlet , and its a 15A breaker.

anyone know how to work this out so I know how much power its going to be using so its still safe?

nevermind , I think I figured it out .

Its kinda complicated and you use ohm's law the links bellow should help.

http://en.wikipedia.org/wiki/Ohm%27s_law

http://www.the12volt.com/ohm/page2.asp

actually , it wasn't that complicated at all.

you just add up the total wattage of all the given devices in the circuit and divide by 120.
which will tell you the total current. which is what I was looking for .

only thing to keep in mind , is that anything more than 80% of the value of the breaker is considered overloaded.

For the application I have in mind , I should be well under the total value of the breaker .

Only thing you have to watch out for now is tripping the breaker in the fuse box.

Quote:

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Originally Posted by pliskin

I've got 5 tubs set up with 11" flexwatt heat tape, each one is 1ft in length.

the instructions say that each foot uses 20 watts , but wanted to add some more stuff on another power bar for my display tank using the same outlet. I'd like to work out how much current its going to be drawing so I don't keep tripping the breaker, or cause a fire .

In the display tank I was planning to put in a fan , light, and a water pump for a waterfall.
I want to have two power bars on one outlet , and its a 15A breaker.

anyone know how to work this out so I know how much power its going to be using so its still safe?

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Volts x Amps=Watts Just remember...That is the MAXIMUM amount for that circuit. Never run a circuit at it's max.

Looks like you figured it out Watts divided by Volts = Amps. If you have any more electrical questions feel free to PM me I am a master electrician I can help you with you questions.

I'm actually studying for the ASVAB right now, and this is one of the things I have to know for this test. So, I remember back to my high school days where my science teacher taught us about this pyramid, which will help you to visualize how to get Watts, Voltage, or Amperage in a situation where you have at least two of the numbers.

I whipped this up in Photoshop real quick - hopefully you'll find it useful :)

http://nathanledet.com/electricpyramid2.jpg

How it works:

If you have two numbers, then you cover up the letter that you need. In this case, you need to know Wattage. So you take your hand/finger and cover up the "W" and that leaves you with "A" (Amps) and "V" (Voltage). Since they are side by side, that indicates that you multiply those numbers to get wattage.

Lets say you need to know Amps - You would then cover up the "A", and then notice how the "W" is on top of the "V" - this indicates that you would divide W over V

It would work the same way if you needed to know Voltage - Cover up the "V", and then notice how the W is over the A, indicating that you would divide W/A

Hope this helps :)

Quote:

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Originally Posted by 2kdime

Only thing you have to watch out for now is tripping the breaker in the fuse box.

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yes , I know. as I said, I'll be well under the 15A of the breaker . I'll be around the 30% range .

and, thanks to everyone else that replied.
thank-you Jason , If I have any other questions I'll keep that in mind.

This is actually a very good thread and is probably something that is overlooked as a collection expands. When all you have is a couple snakes, it isn't something that needs to be worried about to much, but when you start having dedicated snake rooms and custom wiring done to accommodate multiple racks, it becomes something that has to be accounted for.