Electrical wiring question

[bdog]

I am adding a sub panel. I am going to add six 110v outlets each with their own 15 amp breaker. Each outlet will have a constant load of about 12 amps.

My plan was to run 6/3 from the main panel on a 50A breaker to the sub panel. Distance is about 50'. At the sub panel I was going to run three outlets on one leg and three on the other. 12 ga for the outlets. 6 ga is rated for 55 amps.

My question is the 6ga can handle the load on the hot legs no problem but what about the neutral? Can a single 6ga neutral handle a continuous 36 amp 120 load on both legs? Since the legs are out of phase I am not sure. Will the neutral be seeing 72 amps and burn up or will it see very little load since the two legs feeding it are nearly balanced and out of phase?

 

[Gordon Gould]

The 6 Ga neutral to the sub panel only has to handle the imbalance currant between the two 120V legs.

gg

 

[CincyFlyer]

If you have a constant 12-amp load, make sure that your 15-amp breakers don't pop on the inrush (depending on what you are running)!

 

[CobyRupert]

The 6 Ga neutral to the sub panel only has to handle the imbalance currant between the two 120V legs.

gg

:thumbsup:

The most it can be out of balance, and thus the most the neutral would ever see is 36 amps. (Basically the maximum that one phase can see.) This would occur if all the loads on one phase were off when all the other phase loads are on.
Conversely, the closer the phase loads get to being balanced, the closer the neutral current gets to zero.

Also remember:
A sub-panel in another building needs it's own ground electrode (ground rod), in addition to the ground conductor you bring from the main panel. And:
You should NOT bond the (white) neutrals (or neutral bar) with the (green) grounds (or ground bar, or panel enclosure) in the sub-panel. The neutrals should be isolated (from the ground) in the subpanel.
This bonding should only be done in one place. (Usually at your main service panel, or first service disconnect if one is upstream of main panel)

 

[Zebrafive]

One other thing to check is if code requires a main breaker in your sub panel. I know there is no "need" for one, BUT where I'm located, if you have more than 6 circuits, a main breaker is required in the sub panel. So if you are considering more than 6 circuits, consider a sub panel with a main breaker.

 

[buickanddeere]

If there is 3 x 12 amps on line 1 and 3x12amps on line 2. Neutral current will be zilch, zero nada .

 

[aeblank]

A sub-panel in another building needs it's own ground electrode (ground rod), in addition to the ground conductor you bring from the main panel.

I am fairly confident this is *not* true. We did that, and my inspector made us disconnect/tape off one or the other (cannot remember for sure which, but I'd bet on it being the ground rod). I'd be asking the inspector about this one.

You should NOT bond the (white) neutrals (or neutral bar) with the (green) grounds (or ground bar, or panel enclosure) in the sub-panel. The neutrals should be isolated (from the ground) in the subpanel.
This bonding should only be done in one place. (Usually at your main service panel, or first service disconnect if one is upstream of main panel)

I believe this to be true though and agree with this. Ground loops/radio hum/etc.

 

[bdog]

Thanks guys.

I seemed to remember this was the case but wasn't sure.

The panel will be in my house, not a separate building so no additional ground rods needed and the ground and neutral will remain isolated.

The load is 12 amps max and should not exceed that or have a high startup. It is all computers - specifically bitcoin miners.

 

[hawkeye08]

Thanks guys.

I seemed to remember this was the case but wasn't sure.

The panel will be in my house, not a separate building so no additional ground rods needed and the ground and neutral will remain isolated.

The load is 12 amps max and should not exceed that or have a high startup. It is all computers - specifically bitcoin miners.

Let us know if you strike it rich... tell us how you did it.

 

[bdog]

I think the ship has sailed on getting rich from them but they are still a viable investment I think. An approximate 2k investment in a miner should yield about $500 a month in bitcoin at current prices and will consume about $100 a month in electricity for $400 net. Should pay for itself in about 5 months and then after that give you $400 a month profit. Of course this all assumes the prices and mining difficulty stay similar to what they are now.

I certainly don't want to bet the farm on it but I am going to run six of them and see what happens.

The early adopters won the lottery if they managed to keep their coins until now. Back in 2009/10 a basic household desktop computer could mine around 25 bitcoins a day. At today's prices that would be over 100k a day!! If you ran it for a year back then on your regular old computer and kept the coins until today they would be worth 36 million dollars.

 

[roadhunter]

Am I the only one who doesn't understand what mining an internet currency entails?

As far as electrical no problem on the neutral current in that situation. The first time I wired a welder plut I was astonished to find no neutral. Then I learned how it works.

If you really want to blow your mind try 3 phase. Just switch any 2 wires and the motor will switch directions. It's fascinating to a novice like me. Next project is a 25 HP rotary phase converter.

 

[bdog]

Here is a decent video that explains it Bitcoin Mining Explained - YouTube

 

[buickanddeere]

rotary convertors are a piece of history from the bad old days when there was nothing better to make do with on the cheap. Now we go with a lower cost and more efficient variable frequency 3 phase drive supplied by single phase. Allows current limiting, torque limiting, start and stop ramping, reversing and variable rpm.

 

[LD1]

I am fairly confident this is *not* true. We did that, and my inspector made us disconnect/tape off one or the other (cannot remember for sure which, but I'd bet on it being the ground rod). I'd be asking the inspector about this one.




I believe this to be true though and agree with this. Ground loops/radio hum/etc.

Your inspector is an idiot.

 

[LD1]

I don't understand Bitcoin mining either. Wouldn't it seem the more people that do it, the less money you can make?

 

[gary49]

Hope you meant 6/3 with ground. Sub panel will need a separate ground bar to meet code. If you were running to a separate structure, three conductors would be enough, you would need a ground rod or equivalent grounding electrode and the neutrals and grounds would be on the same bar with the bonding screw in place. Separate building is considered to be another service.

 

[bdog]

Yes 6/3 with ground.

 

[bdog]

I don't understand Bitcoin mining either. Wouldn't it seem the more people that do it, the less money you can make?

Yes and no. The algorithms are such that a new bitcoin is mined every ten minutes. It self adjusts making the difficulty harder when more people mine or as technology gets faster. So when more people do it they are harder to get but the price of them seems to go up accordingly. Right now it takes over $1000 of electricity to mine one. The bitcoin network as a whole consumes something like 45 million kilowatt hours a day. It is kind of like mining for gold - it takes money to get it.

If you try and mine on your own it would take forever to get a bitcoin. People join pools and they all work together and when one is found they split the profits.

The best miner on the market is the antminer S9. These cost about $3,500 each right now but at current prices will get you about $16 a day while consuming about $4 of electricity. $12 a day net will pay for the miner in about ten months and then you profit $360 a month going forward. Amazing returns but the price of bitcoin is volatile and as more people mine they get harder to mine which will reduce profits.

If things hold together long enough for me to recoup my investment I figure everything after that is gravy. Sure would be nice to have $2,160 a month rolling in from some computers sitting in the corner.

 

[LD1]

It's not just the mining. I have a hard time understanding the whole concept.

You aren't actually mining anything "physical"

Just some imaginary thing someone came up with out in cyber space.

So when you "find" a bit coin...you really found nothing.

And who pays? Why? Why would anyone want a bit coin? Other than the foil hat types?

Just don't understand the craze and fad. And with computers ever-changing, and getting faster and faster....what you anticipate to payoff in 10 months.....by then your tech will be dated, coins getting harder to find so it might take you even longer to break even....

Just don't get it. Good luck, I am sure you know what you are doing. But Id hate the thought of investing thousands in some make-believe fad

 

[bdog]

I agree it is a hard concept to accept. These bitcoins have been going nearly ten years now though and currently have a total market value of around 70 billion. When it started out it was definitely some tin foil hat computer nerds but now it is really gaining widespread acceptance.

The whole thing is based on the fact these coins are super secure, can be transferred to anyone anywhere for cheap, and are limited in supply. They are controlled by the individual that has them with no middle man involved in the transactions. They really help facilitate a global economy. I could send 100k to someone in China if I wanted to practically instantly for less than $5. It also appears to be gaining in value vs the USD because its limited supply vs the dollars they are printing non stop.

True it was just made up by someone but it has a huge following now.

I am not trying to sell anyone on it please don't misunderstand me I am just trying to explain it.