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I am purchasing a new house with only 1 open breaker. I believe it is a 100 amp main. Can I run 2 100 amp sub panels feeding them with 60 amp breakers? One will be due to needing the open space for the 60 amp breakers since it currently only has one spot and a few spares. The other sub panel will go in the detached garage as it currently doesn't have any power. the sub panels would not be in line but both fed off the main itself.
 
Thanks.

I'd be inclined to upgrade to a 200Amp service, because a 60Amp sub off a 100Amp main will be at best marginal.
 
ok i don't really have the money in a budget for the 200 amp upgrade that's why i was wanting to do the 60 amp sub panels, since i don't need a lot in the garage or for the sub in the house. i've budgeted 10k for other things.
 
The service panel will dictate the max. main breaker allowed for that service, and if it is 100Amp, then that is the max for the existing buss's.

The use in the house will be determined by the number of elec. appliances serviced, as well as a general use calc., or an "every light in the house is on" method.

If your proposed load for the garage is 60Amp, then you'll need to sub for that, which may eliminate any spare breaker space you have, as you have indicated.

There's no magic bullet, just math, and your sig. other.
 
The service panel will dictate the max. main breaker allowed for that service, and if it is 100Amp, then that is the max for the existing buss's.

The use in the house will be determined by the number of elec. appliances serviced, as well as a general use calc., or an "every light in the house is on" method.

If your proposed load for the garage is 60Amp, then you'll need to sub for that, which may eliminate any spare breaker space you have, as you have indicated.

There's no magic bullet, just math, and your sig. other.
There is a difference between a Lighting and Appliance Panel Board and a Service Disconnecting Means. Even when both of those are housed in the same cabinet they are 2 distinctly different things. What the OP asked was could he install 2 breakers using one for each of the 100 ampere Lighting and Appliance Panel Boards. The answer is yes. A new Service Disconnecting Means would be installed which would have 2 main breakers in it. Each of those would supply 1 Lighting and Appliance Panel Board. The National Electric Code (NEC) specifically allows up to 6 separate Breakers, Fused Pull Outs, switches, or some combination of them to serve as the Service Disconnecting Means. The entire service bust be arranged so as to be able to be disconnected by 6 throws of the hand. This doesn't have some scientific or engineering basis. It is just the number at which the Code Making Panel; which is responsible for the section of the NEC which covers services; decided to call a stop to the number of operations that would be needed to deenergize the entire Service. He will have to do the Service load calculation to make sure that it is within the ampacity of the Service Entry Conductors.

Were I doing the upgrade under tight budget constraints I might install a 200 Ampere, Main Lug Only (MLO) panel with only 12 slots. I could then install up to 6 double pole breakers in that panel to Serve as the Service Disconnecting Means. Then I might install 2 100 Ampere breakers to supply those 2 panels. That would give the OP the flexibility to add up to 4 additional double pole breakers to serve loads which might be added later. One thing to remember is that Service Entry Conductor size is determined by the calculated load and not by adding up the ampacity of the separate Service Disconnecting Means.

I rewired a youth summer camp that had several small panels placed in a variety of buildings. I installed a 400 Ampere MLO panel board to which the Electric Utility terminated their Service Entry Lateral. I then installed Feeders based on the size of the calculated load in each building, The feeders were protected at the Service Disconnecting Means by a breaker which was sized to the ampacity of the conductors after the conductor size had been raised to compensate for voltage drop. The Building Disconnecting Means at each building's panel was sized to the buildings calculated load. That resulted in the Lighting and Appliance Panelboards' main breakers being a lower ampacity than the Service Disconnecting Means breaker which protected the feeder which supplied that panel. This was done so that if an overload occurred it was much more likely that the Building Disconnecting Means breaker would open prior to the Service Disconnecting Means breaker opening. The total of the 6 Service Disconnecting Means breakers certainly exceeded 400 Amperes but the calculated load did not.

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Tom Horne
 
I read it as the OP having a 100Amp service with a couple of breaker slots vacant, from which the OP wants to sub feed a panel with several breaker slots, from which he wants to run a subfeed to the garage.
 
I read it as the OP having a 100Amp service with a couple of breaker slots vacant, from which the OP wants to sub feed a panel with several breaker slots, from which he wants to run a subfeed to the garage.
Then perhaps you missed his last line. "the sub panels would not be in line but both fed off the main itself." If you read all of his posts I think you will find that he is being fairly clear. For instance he asked "would you recommend a different way to do the sub panels? Larger breakers on the main?"

I think he needs a least costs solution for right now and if that is true putting in a 12 slot MLO panel "which is Listed for use as Service Equipment" is probably the answer.

Let me just say that I do not like the term "Sub Panel." It is not defined in the Code and and the lack of a common definition seems to lead to quite a bit of confusion. There are 2 types of panels defined in the Code. they are a "Lighting and Appliance Panelboard" and a "Power Panelboard." The definition depends on whether 10% or more of the circuits "are 30 amperes or less and have a connection to the Neutral of the panel board."

Even when the Service Disconnecting Means is located in the same cabinet that does not change the nature of the panelboard. All panels that are supplied by Service Conductors must be "Listed for use as Service Equipment." Panels which are supplied by Feeder Conductors do not have to be "Listed for use as Service Equipment." In this case both the panel in the house and the panel in the detached garage would be supplied by Feeders protected by breakers that are mounted in a Panelboard that is MAIN LUG ONLY and Listed as Service Equipment. Panels which meet both conditions will only have room for 6 Double Pole Breakers or less.

The panelboard in the house will have to be converted to have separate Neutral and Equipment Grounding Conductor busses. Once the Service Disconnecting Means and the main bonding jumper are not in that panel no connection between Neutral Conductors and Equipment Grounding Conductors is permissible.

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Tom Horne
 
Did you miss that this is a single family residential service?
How many single family dwelling have a separate mains and distribution panels for lighting and appliances?
 
Did you miss that this is a single family residential service?
How many single family dwelling have a separate mains and distribution panels for lighting and appliances?
No I did not "miss that this is a single family residential service." I have worked in the electrical craft for 50 years old son. I have done electrical work on French Frigate Shoal, Alaska, Tierra del Fuego, Uganda, and several other places I no longer recall the names of. I have been inspected by inspectors from the US Army Corps of Engineers to the Alexandria Virginia Inspector who chaired the Code Making Panel Coordinating Committee. I have never failed an inspection. Not Once!

Installing a Main Lug Only panel which is Listed as Suitable for use as Service Equipment is a very common way of economically upgrading older homes that have multiple panels or were the existing equipment is maxed out. It is one of the methods which MUST be considered when working under the Federally Assisted Code Enforcement (FACE) program which brings housing owned by the elderly up to minimum safety standards under the nationally recognized building codes. I can show you several homes within 20 miles of my home were it has been done. It is often used as a way of dealing with Split Buss panelboards when additional breaker spaces are needed in a home's electrical system. It is also a very good way to hold down costs for cash strapped customers that need to add capacity to their home without the cost of fully replacing the existing electrical panel. The idea that because you have never seen it that it has never been done is the hallmark of those who have worked in only a few jurisdictions in their time in the craft.

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Tom Horne
 
That's good.

The OP is in OHIO, so you mite stop by and show him exactly how he can accomplish what he wants to do, since you've done so many.
 
I want to keep the main service at 100 amps. Take out 3 breakers and move them to a sub panel, since there is only one open slot. taking out the 3 breakers will give me 4 slots to run 2 60amp breakers to run 2 sub panels. One sub panel next to the main and one sub in the detached garage. I want to run 60 amps to the garage because i will be putting a 20 amp welder in there which will rarely be used along with miter saw table saw and so on. All the lighting will be LED on a 15 amp breaker and roughly 4 15 amp outlets excluding the 20 amp outlet. I know that only adds up to 50 amps so I would have space to add another 15 amp if need be. The sub in the house would have 1 extra space as well. this would put me in the same boat as now with only having one open breaker slot, but i would have everything else done this way. Since breaker panels are only $20 a piece and breakers aren't much this would be the most cost effective way for me except for the expensive 4 gauge wire to the garage, but it is what it is there. I seem to see this is what people do, but if this is a recipe for disaster then I wont do it this way. I dont care about extra breaker slots at the moment.
 
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That's what I thought you meant all along.

Maybe TOM could supply you with a line drawing and an equipment list so you could first find out if it can be permitted in your area, I know the sub panels can, and determine the cost so you will know if your budget will fit.
 
That's what I thought you meant all along.

Maybe TOM could supply you with a line drawing and an equipment list so you could first find out if it can be permitted in your area, I know the sub panels can, and determine the cost so you will know if your budget will fit.


the panels and breakers are less than $100. the wire different story. conduit is cheap and ground rod is cheap. I'm sure I cant do it for under 500, but i know any other option would be expensive.
 
The trench can be a challenge, as well.

Solid conductors are the least expensive. I prefer stranded because they go around corners better and there is greater ampasity.
 
The trench can be a challenge, as well.

Solid conductors are the least expensive. I prefer stranded because they go around corners better and there is greater ampasity.

Trench will be easy the way the house is and things. I plan on running a second conduit as well just empty. Does what i'm saying make sense and will it be ok to do that way?
 
Just curious, what's the plan for the 2nd conduit?
 
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