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Discussion Starter · #1 ·
Running 2224 to a detachedd structure. I haven't decided on the amp breaker yet to feed the structure. maybe 60 aml, I know it cannot exceed 90 amp. An electric heater will be used in the winter, otherwise there won't be much. I may install a 100 amp subpanel (exterior) even if the circuit feeding is 60 amp.

I also know the neutral and the ground must not be bonded/connected in the subpanel. In addition I need two grounding rods, 8' deep at least 6 to 8 feet apart.

I am assuming the grounding rods connect to the ground bar in the subpanel which also has the ground feed from the house?

Can the grounding rods be daisy chained or do I need to run each rod back to the subpanel?

If I need to run each rod back to the subpanel, do the grounding rods also need to be connected to each other?

Thank you
 

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A "Handy Husband"
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Run from the panel to the first rod, then on to the second. Why not use a 90 amp supply breaker and get the full amperacity of the feeder?

Sent from my Lenovo TB-X606F using Tapatalk
 

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Discussion Starter · #3 ·
Thank you. So the first rod is connected the grounding bar in the subpanel which also has the 4 awg ground from the main house (via the 2224)?

In my mind I am thinking of the equipment that requires high amps (Central AC, electric water heater, range, electric dryer). The largest item the shed will run is a small electric heater. There is a small windows ac during the summer.

What's the advantage of sending a lot more amperage that I need? Are there any risks or concerns?

If I ever need to, I could swap whatever double pole breaker that I install in the source panel with a higher amperage as long as it doesn't exceed 90 and the breaker in the subpanel.
 

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Licenced Electrician
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You are not "sending" amperage. Amperage is based on the load connected. The breaker limits the current and it's job is to protect the conductor. A 90A breaker is no less safe than a 60A breaker.

Do you have a governor on your car? It's likely capable of speeds in excess of any limit you typically encounter. Same thing.
 

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As mentioned above you are NOT sending anything. Perhaps you need to buy a book. I am not trying to be rude, I am trying to keep you and your building safe. You can do this but you simply must have an understanding of how electricity wors.
 

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Discussion Starter · #6 ·
As mentioned above you are NOT sending anything. Perhaps you need to buy a book. I am not trying to be rude, I am trying to keep you and your building safe. You can do this but you simply must have an understanding of how electricity wors.
Thank you, that makes sense.
 

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Running 2224 to a detachedd structure. I haven't decided on the amp breaker yet to feed the structure. maybe 60 aml, I know it cannot exceed 90 amp.
Good choices. The smallest breaker that will take #2 wire is 60A. It's also $10-ish, same price as the small 240V breakers. 70A and larger breakers cost more money.

I may install a 100 amp subpanel (exterior) even if the circuit feeding is 60 amp.
Feel free to take that to the moon. The key is to get enough spaces so you never run out. Spaces are laughably cheap, but running out is an expensive problem involving re-purchasing breakers to get tandem/quad breakers, or even a second sub panel. By far the cheapest is to just get more spaces at panel purchase time.

The largest item the shed will run is a small electric heater. There is a small windows ac during the summer.
If that's a plug-in space heater, think about replacing it with a 240V Cadet baseboard heater.
#1 it's far safer. UL approves Cadet heaters to run unattended, they forbid that for plug-ins.
#2 it's cheaper in the long run. A space heater lasts maybe a season, so you have to buy them over and over. A Cadet will last 40 years.
#3 it's more powerful, you can have as many as you like as large as 2500W each. So if you heat the space only occasionally, it will be faster to come to temperature. Once it's at target temperature, cost will be the same either way, since it's cycling on/off with the thermostat.
#4 supports external thermostats for even heating.
#5 there's nothing underfoot or in your way.
 

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Red Seal Electrician
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x2 on the baseboard heater vs a portable.

I can usually get them for free or a couple $ at a garage sale.
 

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Perhaps you need to buy a book.
Nobody else does! :D

For a fixed voltage [120v or 240v] the load resistance decides what amps will pass.

For 90A @ 240v it's 240/90 = 2.7 ohms [R=E/I] & 240 x 90 = 21.6 kW, [P=ExI]. . . about what my house would draw with everything turned on.

For a 1200w, 120v hair dryer, it's 1200/120 = 10 A [I=P/E] & 120/10 = 12 ohms [R=E/I].

For a 60w, 120v bulb it's (60/120 = 0.5A [I=P/E] & 120/0.5 = 240 ohms.

Once you know the V, you need one other value to determine the last one.
It's easy to chase your own tail with this.

From these you can say
P=(I^2) x R &
I^2 = P/R &
R = P/(I^2).

For the hair dryer, I = 10A, I^2 = 100, R = 12, so P = 100x12 = 1200W.
 
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