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Old 02-24-2010, 11:57 AM   #16
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Wiring Garage for 220


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Originally Posted by Scuba_Dave View Post
My 60a sub I bought a 100a panel & fed it with 60a
There is a section in the code that requires a Min 60a disconnect
There has been debate about if a 100a sub with a 100a main breaker & being fed with 40a meets code
One local Inspector (not here) required a 60a min disconnect in the main panel
That I will run past the local building department. To be honest, I don't quite grasp this, but I suspect that local inspector is wrong. I think the idea is that a user can disconnect power in case of a problem. Disconnects can be located in master panels, but are best if in a sub where the sub is in sight of the user. Also, it seems to reference a "minimum" disconnect. You have the main in the master panel, which enables someone running to the master in the case of an emergency to kill all power. But I am no electrician and not even in construction trades, nor have I seen the code. My electrical training consists of Marine Corp aviation ordnance A school and a high school elective in radio and electronics. Both are really electronics as opposed to electrical. I have slept at a Howard Johnson's.

I really shouldn't have even commented on the disconnect issue, as all I am doing is showing my ignorance of the subject. It just seems that having the disconnect closer to the potential problem is best.

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Old 02-24-2010, 03:29 PM   #17
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Wiring Garage for 220


It is not required.
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Old 02-24-2010, 04:09 PM   #18
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It is not required.
What is not required ?
A disconnect at the panel ?
Or a min 60a disconnect ?
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Old 02-24-2010, 04:48 PM   #19
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Either!
A 60 amp rated disconnect is only for feeding a deattached garage or structure, and a sub does not need a disconnect at the sub location.
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Old 02-24-2010, 04:54 PM   #20
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Ah...just realized...I was thinking detached...Thanks
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Old 02-24-2010, 05:00 PM   #21
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Wiring Garage for 220


I just got off the phone with someone at an HD. I called to get a rough idea of some costs of running this subpanel. If this person is right, my 200A service isn't adequate.

I know that what they say is not exactly gospel, even if they think they know of what they speak. (Last week when I was at an HD, a guy in electrical who said he has 4 years as an electrician's apprentice told me to swap out a 15A breaker on a 15A circuit for a 20A or 30A.)

This woman said that I should total the amperage of all the breakers in my main panel, and if it was at or near 200 I couldn't run a sub off of it. even if I have 8 open breaker slots. Is that correct? If it is, the main was overloaded at the time of construction as the total rating of the present breakers is 335A.

Also, looking at my little electrical wiring book for dummies, it says, "A 240-volt circuit is always dedicated to one outlet." Now I see why I would want a sub panel with room for 6 breakers. I need one 240 outlet now for the table saw, and will probably need at least one other. That accounts for four of the six breaker bays. I want one of the two remaining slots for a series of 110. If the cost isn't much more, I may spring for a larger subpanel.

I am most concerned for the time being with what the HD employee said about my main being overloaded if the total amperage of all breakers exceeds the rating for the main panel; 200A. What is she thinking?
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Old 02-24-2010, 05:05 PM   #22
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BS! If that was the case, we would all be tripping breakers.
The load on the main panel is based on usage not what the breakers add up to be.
Quit asking HD emploees anything but where the parts are.
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Old 02-24-2010, 05:26 PM   #23
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Whoever told you that has no CLUE about this & is an idiot
Like JB said DO NOT ask HD employees about stuff like this
Sometime you will find someone who knows a little code, but not usually
I have a 200a main, (2) 100a subs, 60a sub & my total breakers in amps is in the thousands of amps
My main panel has 640a total breakers all calc'd at 240v

If your electric bill isn't like $1000's a month - like ALL electric heat, HW etc then you are fine

A 240v circuits CAN have more then one outlet under certain circumstances
Usually since devices have different requirements or may take a high percentage of a circuit they are dedicated
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Old 02-24-2010, 08:36 PM   #24
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Quote:
Originally Posted by jbfan View Post
BS! If that was the case, we would all be tripping breakers.
The load on the main panel is based on usage not what the breakers add up to be.
Quit asking HD employees anything but where the parts are.
I have to say you are right on. BTW, I didn't ask the person about the main panel capacity, but only asked how much for a 60A subpanel. She offered this up. Even the little book sold by HD says, "if you add up the amperage of all the breakers in the box" the total may well exceed the overall rating of the panel" and gives an example of a 100 amp panel with breakers totaling 220, as presently configured I am fine with a 100 amp panel. The same book provides a method of estimating panel requirements. Per the suggested worksheet, I can almost get buy with a 100 amp panel, though I have a 200 Amp master. Ergo, my eight open breaker slots.

Quote:
Originally Posted by Scuba_Dave View Post
Whoever told you that has no CLUE about this & is an idiot
Like JB said DO NOT ask HD employees about stuff like this
Sometime you will find someone who knows a little code, but not usually
I have a 200a main, (2) 100a subs, 60a sub & my total breakers in amps is in the thousands of amps
My main panel has 640a total breakers all calc'd at 240v

If your electric bill isn't like $1000's a month - like ALL electric heat, HW etc then you are fine

A 240v circuits CAN have more then one outlet under certain circumstances
Usually since devices have different requirements or may take a high percentage of a circuit they are dedicated
If I thought the guys at HD knew what they were talking about, I wouldn't go online to find out the right way of things. Using the work sheet in HD's own book "Wiring 1-2-3" I calculated that I need a 117 A main, if there was such an animal, and that is rating my appliances generously. I don't doubt that a 200 amp main is plenty for my purposes.
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Old 02-25-2010, 02:53 PM   #25
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Wiring Garage for 220


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Ah...just realized...I was thinking detached...Thanks
I should have made that clearer. Thought you may be thinking disconnect when you asked about the length of the run. Nothing will be over 50'.

Thinking about this more, I am definitely sold on going with a sub-panel. Went to price things at the same HD and the same very nice but not too bright "apprentice electrician" for some reason probably bored and trying to be helpful, while demonstrating his knowledge) tried to convince me not to go with a sub and just come off the main, as I have the 8 open bus slots on the main.

I am sticking with the sub. You guys recommend it, everyone I know who has wired their garage for 240 uses one, I like it being easily within a few feet of my work area, and I will be left with five slots on the main for future use. (When the walls are open for some reason, like remodeling, I would like to upgrade some of the questionable but legal house circuits.)

I am now planning the garage circuits. I 86'd my idea of running the 120 off of a single alternating hot leg of the 4 wire 240 circuit. I still don't know if that would be legal or wise, but I will play it safe and go with a dedicated 120 for garage lights and 120 receptacles. I will then run at least two 240 circuits of the sub. One will be dedicated to my table saw, which is easily rewired from 120 to 240. I may run two 240 receptacles off of the other 240 circuit. I understand that can be done but is not common. Am thinking about getting a larger panel for the sub that will accommodate three circuits feeding one 240.

Not sure how large a double breaker I need on the main to feed the sub. Again, I will check with the city, but am thinking a 40A feeder breaker, and #8 feeder wires will do the trick, even if the sub panel is rated for 60A.

Am thinking that all 240 and the 120 should be on 20A breakers and that 12 AWG is sufficient. I will check what the local building deparment wants for a feed from the main to the sub, but am not to concerned as it will be a short run of no more than 6'. That will be nm, as it will go from the double breaker in the main, out of the main and into the back of the sub where the two hots each connect with a "lug" (?). I have readily understood wiring diagram based on the 2005 NEC that I plan to follow, after I run it by the City inspector.

I also understand there is something about ground fault protection for "readily accessible" 120, not 240, receptacles in garages. What is the better way to do that? What of using a GFCI breaker at the sub panel, if there is such a creature?

Here is the NEC 2005 based wiring diagram. I am posting it because I realize it may not include more recent changes to code. ANYONE VIEWING THIS, I AM JUST A DIYER, NOT AN ELECTRICIAN, AND THIS IS BASED ON AN OLDER VERSION OF THE NATIONAL ELECTRICAL CODE. I DO NOT KNOW IF IT WAS THEN OR IS STILL UP TO CODE.

Also note that a poster who seems to be knowledgeable posted what seems to be the same diagram but noted that the diagram "lays out the main things that need to be considered but is not intended as a "how to" diagram". I believe that he poster "Stubbie" may be the creator of the diagram. See his post at lays out the main things that need to be considered but is not intended as a "how to" diagram.
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Old 03-03-2010, 02:51 AM   #26
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I want it clear that the wiring diagram in the above post is not my work, but something I copied from another thread on another site. I really don't know if it is correct or not, as I am only a pencil pusher. However, I wouldn't post it if I didn't think it may be correct and the experts here may get around to commenting on it. Still, it is based on a four year old version of the NEC.
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Old 03-03-2010, 03:26 AM   #27
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Looks good to me.
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Old 03-03-2010, 06:20 AM   #28
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Looks good to me.
ME 2
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Old 03-07-2010, 12:54 AM   #29
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Quote:
Originally Posted by Scuba_Dave View Post
My 60a sub I bought a 100a panel & fed it with 60a
There is a section in the code that requires a Min 60a disconnect
There has been debate about if a 100a sub with a 100a main breaker & being fed with 40a meets code
One local Inspector (not here) required a 60a min disconnect in the main panel
I sometimes get it, even if it takes a while. I ran this by stubbie, sort of, but forgot to give him the model # so he could really check it out.

For about $53 including tax, I bought a 100 Amp main main breaker panel with space for 20 single pole breakers at the HD. It came with 5 20-Amp breakers and, yes, a door. The 100 A main breaker is factory installed.

Google.com/products has them starting at $67 plus tax and shipping. Schneider Electric, the manufacturer, is over the top with a list price of $528. Apparently the list price is heavily discounted.

Now I will have to see if local code permits me to use it "feed it off" a 60 amp on the main panel.
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Old 03-07-2010, 03:34 PM   #30
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I am getting ready to mount the panel in the garage (but will wait to see if I get any responses to prior question re the panel I selected) and would appreciate some tips as to the mechanics of installing the actual panel.

The walls and ceiling are all semi finished. bu which I mean they are covered with drywall covered with a very thin layer of paint. I have been planning to run the circuits on the garage side of the wall with emt, which means a surface mounted panel.

I should add that I have some experience, not a lot but some, with modifying some existing circuits by cutting drywall access holes, drilling through ceiling plates (not quite the right term) and using a fishing tape.

My main concern is not damaging the cabling inside the wall, and of course not zapping myself, as I will have to cut into the drywall near to the top of the main panel, which is approximately opposite of where I am thinking of hanging the sub panel. That raises an issue as to the proposed selection.

The place I have selected is roughly in the middle of the westerly wall of the garage. I don't know if local codes have any special requirements, but have read elsewhere that a panel is to be readily accessible. Although we never park our cars in the garage anymore, we are supposed to per Association rules and a later owner may want to park there. Is the location a problem?

Setting aside the issue of the location, I am going to be cutting have to cut into the drywall in that area in order to get drop the feeder cable down into the main. To avoid damaging the the existing cables and frying myself, I will shut off all power. Still, I can't shut off the power going to the power company side of the box and, even if it is shut off, I can I damage it? I don't know if it is shielded or in conduit. I expect it would enter form below and plan on making all cuts above the panel.

Once I pretty well know where I want to cut, I guess it would be safer not to use my drywall saw but to use the dremel's drywall attachment set to just pierce the sheetrock.

As I have access to a circuit tracer, I will attempt to mark where the circuits are and where not to cut before. I will also gut a smaller inspection hole a couple of feet above that area and try to see into it before cutting down there. My view may be obstructed by a fireblock. I dunno.

If you have any suggestions or criticisms, I have found them to be well worth hearing. TIA.

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