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Discussion Starter #1 (Edited)
In part of construction of the new garage/shop I am planning out power. Here are my thoughts:

- I would like to install a outdoor load center near my barn. My need for this is for outdoor outlets for horse buckets, pool pump, outdoor wood boiler and I'd like to move the feed for the barn to the sub panel(there is no panel in the barn). Right now it goes underground into the main panel. I would then like to run power to the garage from this outdoor panel. the outdoor panel would be 130' from the main panel, and the garage is 200' from the sub panel.

- Can I daisy chain 2 sub panels like this? I understand the loads would need to be calculated. If I did a 125 or 150A outdoor sub panel, could I run a 100A sub to the garage? I did my calculations on wire size from the main panel to the outdoor panel and plan to use copper USE #2 direct burial for the 2 hots and neutral and a #6 for the bonding ground. According to my calculations I can run a 150A load up to 131' @ 3 percent voltage drop. I plan on using aluminum 4 wire to the garage but have not done any calculations yet.

My biggest concern is keeping it all to code. I am not a NEC nut that knows the book like a bible. Thanks for any help!
 

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In part of construction of the new garage/shop I am planning out power. Here are my thoughts:

- I would like to install a outdoor load center near my barn. My need for this is for outdoor outlets for horse buckets, pool pump, and I'd like to move the feed for the barn to the sub panel(there is no panel in the barn). Right now it goes underground into the main panel. I would then like to run power to the garage from this outdoor panel. the outdoor panel would be 130' from the main panel, and the garage is 200' from the sub panel.

- Can I daisy chain 2 sub panels like this? I understand the loads would need to be calculated. If I did a 125 or 150A outdoor sub panel, could I run a 100A sub to the garage? I did my calculations on wire size from the main panel to the outdoor panel and plan to use copper USE #2 direct burial for the 2 hots and neutral and a #6 for the bonding ground. According to my calculations I can run a 150A load up to 131' @ 3 percent voltage drop. I plan on using aluminum 4 wire to the garage but have not done any calculations yet.

My biggest concern is keeping it all to code. I am not a NEC nut that knows the book like a bible. Thanks for any help!
Sounds like you need someone to provide you with a one line diagram. If you are an electrician then you would not be asking for this basic information. Will there be permits and inspections done? I only want you to do it once and do it right so I think you need more than internet advice for this type of install.
 

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Discussion Starter #3
Sounds like you need someone to provide you with a one line diagram. If you are an electrician then you would not be asking for this basic information. Will there be permits and inspections done? I only want you to do it once and do it right so I think you need more than internet advice for this type of install.
Who said I was an electrician? I said I was planning out the job, not doing it. You COULD do what I am asking but the rules change every year and some people know the book because they deal with it everyday. I am not asking for detailed instructions here so I think you took my post wrong.

Thanks for your concern though.
 

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Local Codes need to be followed if you do.

I have done this but the panel lugs need to be approved for 2 wires of the type your using.


Question: Can a subpanel have power supplied from a*circuit*breaker into another subpanel? In other words, can*you*daisy-chain subpanels?
Answer:*Yes.
The main electrical service panel is where branch circuits originate. A branch circuit consists of the circuit conductors between the final over-current device protecting the circuit and the lights, receptacles and equipment supplied by the branch circuit.
There are three main types of branch circuits:
General-purpose branch circuits for illumination and other general purposes
Appliance branch circuits that supply power in the kitchen for countertop receptacles, such as small appliances
Individual branch circuits that only supply one utilization equipment, such as a central heating gas furnace, an electric clothes dryer, an electric range and so on.
The*main service panel also may contain fuses or circuit breakers that supply “feeder” conductors to downstream subpanels. A feeder consists of the circuit conductors that originate at the main service panel and are routed to the subpanel, in which there are branch circuit over-current devices for the downstream branch circuits.
You could daisy-chain a feeder from the main service panel (Panel A) to a subpanel (Panel B), and then run another feeder from Panel B to another subpanel (Panel C). There really is no limitation to this concept, as long as every set of feeder and branch circuit conductors are properly sized and rated in amperes, and each feeder and branch circuit has the proper over-current protection (fuse or circuit breaker).
Always check with your local electrical inspector about the specific code requirements in your area.*
Question answered by John Williamson, Chief Electrical Inspector,*Minnesota Department of Labor and Industry*
John Williamson has been in the electrical industry for 40 years and is a licensed master electrician and certified building official. John has worked for the state of Minnesota for over 23 years and is the Chief Electrical Inspector. For the past 25 years John has also provided electrical code consultation to various book and magazine publishers.

I like doing this when the runs are long and the building is big like my Daughters Shop. Solves voltage drop problems and a way of using the power in a building better. So I have 3 sub panels in a row and one main panel feeding them and the other circuits in the building. Was not sure that later more power would be needed and this covered moving big tools around and not re/wiring circuits all the time.
 

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Who said I was an electrician? I said I was planning out the job, not doing it. You COULD do what I am asking but the rules change every year and some people know the book because they deal with it everyday. I am not asking for detailed instructions here so I think you took my post wrong.

Thanks for your concern though.
I am a retired electrical inspector and I figured you weren't an electrician. Sorry if I offended you. It is best to seek help from someone who is knowledgeable in the code and installations. I could design it and install it to code for you but it is a lot of work to do it over the internet. If I lived nearby it would not be a problem. Don't want to see anyone or anything hurt due to an improperly torqued conductor or improperly installed grounding system. It is not a DIY type of endeavor you are asking about!
 

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Discussion Starter #6
I am a retired electrical inspector and I figured you weren't an electrician. Sorry if I offended you. It is best to seek help from someone who is knowledgeable in the code and installations. I could design it and install it to code for you but it is a lot of work to do it over the internet. If I lived nearby it would not be a problem. Don't want to see anyone or anything hurt due to an improperly torqued conductor or improperly installed grounding system. It is not a DIY type of endeavor you are asking about!
I am not offended. All I wanted to know was it still feasible. I am basically planning out for budget purposes. I do plan on doing most of the work myself like digging trenches and mounting the panels, I am not hiring that stuff out as I am very capable. All work WILL be inspected through the local inspector.
 

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The NEC allows (or more correctly, doesn't prohibit) daisy chaining of sub-panels. But you do need proper load calculations and you have to watch how things are wired very closely.

Keep in mind that your 3% max voltage drop should be calculated from the main panel for both sub-panels. If you run from a main panel -> sub panel A -> sub panel B, your wiring load calcs for the main -> sub A have to also meet requirements for your main -> sub B distance.
 

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Discussion Starter #8 (Edited)
The NEC allows (or more correctly, doesn't prohibit) daisy chaining of sub-panels. But you do need proper load calculations and you have to watch how things are wired very closely.

Keep in mind that your 3% max voltage drop should be calculated from the main panel for both sub-panels. If you run from a main panel -> sub panel A -> sub panel B, your wiring load calcs for the main -> sub A have to also meet requirements for your main -> sub B distance.
Thanks Jim. Obviously I can't daisy chain 2 panels of the same amperage, correct? Is there a minimum amperage reduction requirement for the second panel? For example, can I run a 100A sub off a 125A, or does it need to be a 150A?

Just trying to get a rough idea on wire size for budget. Copper is big bucks but I can run a size smaller (main panel is tight)
 

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Thanks Jim. Obviously I can't daisy chain 2 panels of the same amperage, correct? Incorrect
Is there a minimum amperage reduction requirement for the second panel?No

For example, can I run a 100A sub off a 125A,Yes, or even vice vresa or does it need to be a 150A?

Just trying to get a rough idea on wire size for budget. Copper is big bucks but I can run a size smaller (main panel is tight)
The code doesn't say what size one panel has to be to able to feed another panel. It does says that equipment needs to sized for the loads to be served. Does that make sense? Example, my barn has a 100A panel fed from my 200A sub-panel, but it is fed by a 90A breaker. The 90A breaker is the over-current protection, and the 100A breaker in the barn is now a disconnect.
 

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The code doesn't say what size one panel has to be to able to feed another panel. It does says that equipment needs to sized for the loads to be served. Does that make sense? Example, my barn has a 100A panel fed from my 200A sub-panel, but it is fed by a 90A breaker. The 90A breaker is the over-current protection, and the 100A breaker in the barn is now a disconnect.
The 100 amp disconnect in the barn is not even required! Go figure?:dunno:
 

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Discussion Starter #12
The code doesn't say what size one panel has to be to able to feed another panel. It does says that equipment needs to sized for the loads to be served. Does that make sense? Example, my barn has a 100A panel fed from my 200A sub-panel, but it is fed by a 90A breaker. The 90A breaker is the over-current protection, and the 100A breaker in the barn is now a disconnect.
Very well. Thanks. That puts things in perspective for me. Also, by "panel" I mean breaker size. So in summary there is nothing preventing (legally) me from doing a 100A outdoor sub feed which will be feeding another 100A sub feed in the garage assuming everything is calculated properly. The garage sub feed since it's a outbuilding needs a separate ground rod if I am understanding things correctly.

Thanks for everyone's help, I will contact my local electrician and see if he'll work with me with this future project. I really didn't want to waste anybody's time if this wasn't possible and I wanted a little background.
 

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The 100 amp disconnect in the barn is not even required! Go figure?:dunno:
Correct. However, a 100 amp main breaker panel will be a lot less money than a 100 amp lugs only panel. That is because they manufacture and sell far more 100 amp main breaker panels than a lugs only.
 

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Thanks for starting this thread,, I have a similar feed going to a garage, then shed,,

Where I live, this type shed does not get inspected,, but, I tried to "overbuild" the electrical service,,

So far,, I have done everything detailed in this thread correctly,, and the service in the shed works perfectly,,, :good2:
 

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I'm thinking that 200A panel is your "Main" panel. Does that 200A panel feed your house direct from your Service entrance/Meter?
My 200A panel I referred to, is not my main panel. My main is a 200A disconnect outside, which feeds a 200A 40 space panel inside, which in turn feeds 2 100A panels, among other branch circuits. So I have 3 sub-panels and a main disconnect. The main disconnect is what is fed by the meter.
 

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The 100 amp disconnect in the barn is not even required! Go figure?:dunno:
It is because the barn is a separate structure, and I have more than 6 circuits in use. If the barn were attached to the house, then it wouldn't be.
 

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My service is 400 amps and I have 2-200 amp main disconnects that shuts off all power to my place. Then out of those panels one is for my home and the other for the main shop and out buildings. That panel breaks down into feeding 6 sub panels and approx 30 plus circuits inside the main shop. I have a lot of out buildings with sub panels so each one has it own breakers inside the building. Little over kill but very flexible for changes later. This is sorta impossible to say on line how it needs done and only a on/site electrician could have the final say if the inspector will like it or not looking at the rest of the job.
 

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Very well. Thanks. That puts things in perspective for me. Also, by "panel" I mean breaker size. So in summary there is nothing preventing (legally) me from doing a 100A outdoor sub feed which will be feeding another 100A sub feed in the garage assuming everything is calculated properly. The garage sub feed since it's a outbuilding needs a separate ground rod if I am understanding things correctly.

Thanks for everyone's help, I will contact my local electrician and see if he'll work with me with this future project. I really didn't want to waste anybody's time if this wasn't possible and I wanted a little background.
Yes, you can have a 100A feed another 100A, it's not against code. What you possibly face is the loss of selective coordination, which is the downstream breaker tripping before the upstream breaker. In a residential, it's typically not an issue, meaning it's an inconvenience but not imperative. In a commercial setting or health care, it's a huge issue. If you feed your second 100A panel from a 90A beaker in the first panel, then you'll maintain selective coordination, as the 90A breaker will trip before the 100A breaker (in theroy) if the over-current is downstream from the 90A.

Yes, separate structures will need a grounding electrode system installed. Around here, we typically drive 2 ground rods at least 6 feet apart.
 

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My 200A panel I referred to, is not my main panel. My main is a 200A disconnect outside, which feeds a 200A 40 space panel inside, which in turn feeds 2 100A panels, among other branch circuits. So I have 3 sub-panels and a main disconnect. The main disconnect is what is fed by the meter.
Ah, ok, just trying to understand.
So your 200A Bkr is outside and your distribution panel with the feeder Ckts is inside? Or does that 40 position panel have a "main" as well?

Different ways to accomplish the same end results with wiring in general. Seems like that's an added raintight box to me, but maybe location and distance comes in to play with your situation. ?
Maybe your Electric Co requires an outdoor disconnect?
 
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