Help me design my new 240gal setup!

[liveforphysics]

You can always jumper anywire to anywhere . However, the neutral leg sees exactly the same current that the hot leg sees, so its not like you should do anything with neutral that you arent comfortable doing with hot.

And yes, 15amps-18.75amps is exactly what sparky means.

Well, there was that one time I was sitting in the jacuzzi tub with the space heater running, the dishwater going, and I was throwing banana peels into the garbage disposal while running my air compressor to blow bubbles in the tub.

But there will be no more of this kind of fun in my house.

LOL!


This is how my personal electrical wireing code goes. All wires current capicity calculated for 125% of the max possible load I can foresee on the circut. All breaker loading not to exceed 80% of the breakers rated load. I wire that way for anything, and it sure helps me feel better about the danger of electrical fire.

Also, if you own the house, you are legally permitted to make any wireing changes you want. Other people can guide you or advise you, but the second they actually do any of the work, then it becomes illegal (unless they are electrictions).

 

[Slickdonkey]

Right, if I do any jumpering then I'll enclose it in a box.

Bottom line, I think I'll just measure the voltage drop from the panel to determine whether I need to move to 12-gauge wire. That and not load my breakers more than 80%... good practice.

 

[Llarian]

Also, if you own the house, you are legally permitted to make any wireing changes you want. Other people can guide you or advise you, but the second they actually do any of the work, then it becomes illegal (unless they are electrictions).

I thought you usually needed a building permit for anything that involves moving/adding subpanels or something like that?

I'd be thrilled if that weren't the case. =)

-Dylan

 

[Slickdonkey]

Regardless of who does the work, I think it helps to have an inspection sticker on the panel if you want to sell your house. Also I'll bet there's a clause somewhere in my homeowner's insurance contract that says they're not liable if my electrical work burns the house down...

 

[sparky52]

Actually Donkey..what I mean is when you calculate the amount of current (amps) you will be drawing on a continuous basis (on for more than 3 hrs) you must size your wire and breaker at 125% of that #.

Example: I find that I am going to be using 12 amps continuously..
12A x 1.25(125%)=15A
I can not use a 15A breaker because you may only load breaker to 80% of its ampacity rating.
15A x .8(80%)=12A...see the connection
20A breaker at 80% =16A...we have a winner.
so I need a 20A circuit to be safe and code compliant drawing only 12A on a continuous basis.....hope this helps bro...later.

 

[Scooterman]

That would be running amps not the start-up surge.

 

[liveforphysics]

slickdonkey, i dont know how you are going to load the circut to test for the voltage drop. Maybe 3 500watt flood lamps and a 250watt or something would be cheapest method?

I am saying this because simply pluging in the pumps dry will NOT have close to the same current pull they will have loaded at the intended head pressure, and testing all that stuff could really get tricky with out having the tank.

 

[sparky52]

Here is a formula to calculate voltage drop...give it a try, it is the easiest way to be sure.

VD(voltage drop)(single phase)=2 x k x I x D Divided by CM

K=12.9 for copper/ 21.2 for aluminum

I=current in Amperes

D=distance to load from power source.

CM=circular mil area of wire
14Awg---4110cm
12Awg---6530cm
10Awg---10,380cm



Example:
I am going to be drawing 12 Amps(dont worry about continuos loads with this it does not matter)

My panel is 100 feet from my reef tank(I wish my house was that big).

I am using #14 wire(4110cm from above)

Copper wire so K=12.9(it is a constant, just roll with it)

So here we go....2 x K(12.9) X I(12Amps) x D(100feet)=30,960

Divide by CM for 14 Awg (4110 from above) and you get..7.53 volts dropped.

Lets use 12Awg...Just divide the 30,960 by the CM I gave you from above(6530)were down to 4.74

Lets get nuts and run some 10Awg....(10,380CM)...oooh just 2.98volts.

Keep in mind the maximum recomended voltage drop on a branch circuit is only 3%. At 120v thats only 3.6 volts. (this is very often overlooked)

 

[sparky52]

Oh I am such a Dumb Ass I just realized that scooter gave us that awsome VD calculator......to much beer not enough sleep..sorry guys.

 

[Slickdonkey]

Haha, thanks anyway Sparky, it's the thought that counts...

Well I'm going to at least measure the voltage at the panel and at the end of the wire and see what it is. You're right that there's no load on it, but if it's much below 117 or so I'll be nervous about hooking anything with a big motor to it.

Probably the best thing to do is have two runs of 12/3 like Sparky said and upgrade to 20A circuits. Not looking forward to spending another few hours wiring, but better to do it right.

 

[Slickdonkey]

Update on progress

Well, I finished drilling the closed-loop holes over the weekend and installed the bulkheads. I was about to start reinforcing the floor when I noticed I bought the wrong lumber (2x8's instead of 2x10's).

I also noticed some cross supports in place when I pulled the insulation, so I'll wait back to hear from the engineer to see if he still thinks reinforcement is necessary.

Anyway, here is a picture of the holes for the closed loop, as well as MH reflectors mounted and Icecap fans in place. Very nerve-wracking to drill into a perfectly nice tank, but it was pretty easy really. Love that acrylic smell.

I also moved my old 75 gallon out of the living room and put the fish and rocks in the QT, so things are progressing nicely.

The stand is also completely finished. It looks nice; I like the color. I especially like the constrast with the black background.

View attachment 11696View attachment 11697View attachment 11698View attachment 11699View attachment 11700

 

[liveforphysics]

Slickdonkey- If you measure with no load on it, it better not have ANY voltage drop at all, infact its actually impossible for it to have a voltage drop with no load. Even if you stuck a 10k ohm resistor inline with the wire at the source, with no load it BETTER read no voltage drop.

The voltage drop only occurs as a function of the current draw/load and resistance in the wires. This was the reason I asked how you were going to test it out without having the equipment setup, and why I mentioned that floodlamps would likely be your easiest route for testing the voltage drop.

Seriously though, IMO, I would definately run bigger wires, or a second set of wires. I know it sucks running wires, but it REALLY REALLY sucks burning your house down.

 

[Slickdonkey]

Seriously though, IMO, I would definately run bigger wires, or a second set of wires. I know it sucks running wires, but it REALLY REALLY sucks burning your house down.

Well said and will do. Besides, what's a few extra hours' work on this project? it's already sucked all my free time for a month.

 

[Scooterman]

Hey enjoy your build, it can be considered the fun part also if you like DIY!

 

[sparky52]

voltage drop

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[liveforphysics]

It does that because of inductive loading, not resistance in the wire.

Take a powersupply, connect any combo of resistors you want to simulate having 10,000miles of wire or whatever you want. Measure the voltage, it will be the same voltage at the source. Seriosuly, try it, its not the resistance that causes the 1000' wire run to read lower, its inductive loading.
To prove its inductive loading, analize both signals on a scope on differnt channels. You will notive the phaseing difference, that phaseing difference is caused by inductive loading makeing a phase shift.
Standard DMM uses 10Mohm load to take a voltage reading. This amount of resistive load when measureing the voltage would NOT apply a measureable amount of load to cause any voltage drop on a meter with precision to 0.01V.

 

[sparky52]

removed by sparky

 

[sparky52]

removed by sparky

 

[sparky52]

removed by sparky

 

[Slickdonkey]

Well, 12AWG it is then!

Thanks Sparky