Replace Sub Load Center w/ new 200 A

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Old 04-09-09, 08:26 PM
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Replace Sub Load Center w/ new 200 A

Hi guys. First time posting on doityourself, but I have a feeling I'll be back for years to come as I'm a first time home buyer and like to do things myself. Plus, I bought an old house and have *tons* of things to do (myself).

One of the first is to upgrade an old Federal Pacific sub panel that's only about 10 spaces to a much larger Square D 40 place 200A panel. This is mainly to allow me to add a 30A circuit for a dryer, but also so I have some breathing room.

I've got several questions about the best way to approach this.

First of all, I've got 200A service to the house. Off of the meter, it comes into to a big shut off box that has 200A fuses in it. From there, it goes into another old Square D load center which is mostly full but more or less fine, so I'm going to leave that one.

The old sub panel is fed through a 60 A (I think it is) breaker which runs through 1.5" conduit to power the sub.

The main panel is a 30 place one, I think.

So I've got this new 40 place one that I'd like to hook up. My main question is, is it possible to just hook it up directly to the shut off like the other main panel is, or do I *have* to sub it off of the main panel?

I've read some of the other postings about this and it sounds like people always sub off of the main panel, partly to deal with getting the neutral and ground properly separated in the sub panels.

I'd prefer to have both of them independently hooked up through the shut off so that I can have full 200A supply to the new LC as well as the old one (since the new LC *is* 200A capable [with no main breaker, by the way, since I knew I had either the main fuses or a breaker in the main panel to protect me]), if that's possible. So, is it?

If not, I guess I'm stuck with supplying the new one through a breaker on the main panel. How large of a breaker am I going to be able to get? I had an electrician quote this job several weeks ago (and came up with a hefty price, otherwise I probably would've had him do it) and we'd worked out a plan where he'd add a 30 space LC and feed it through a 100A breaker in the main panel. Can I go to 150A or even 200A through a breaker in the main panel?

I'm sure I'll have plenty of follow up questions, and I appreciate any knowledge and pointers you're willing to give. I've put some photos of the general setup and the new LC on Picasa:

Picasa Album
 
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Old 04-10-09, 07:02 AM
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So I've got this new 40 place one that I'd like to hook up. My main question is, is it possible to just hook it up directly to the shut off like the other main panel is, or do I *have* to sub it off of the main panel?
A bit confused by what you wrote. I believe you are calling the existing Square D the main but it isn't . The panel with the 200a fuses is your main. The SquareD is a sub panel. Your simplest hook up is going to be from the SquareD panel. If you came off the 200 amp main panel you would have to use wire sized for 200 amp unless you could add a smaller size circuit to the box. That would get expensive and difficult size wire to work with.
I'd prefer to have both of them independently hooked up through the shut off so that I can have full 200A supply to the new LC as well as the old one (since the new LC *is* 200A capable [with no main breaker, by the way, since I knew I had either the main fuses or a breaker in the main panel to protect me]), if that's possible. So, is it?
If the new subpanel is not in sight of the existing SquareD panel it will need to have a main breaker or 6 breakers or less.

Depending on the load on the new sub panel you will need either a 60 amp or possibly 100 amp circuit breaker in the original SquareD panel. If it is not four wire now it will need to be changed to four wires and four wires will need to be used for the new panel.
 
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Old 04-10-09, 07:42 AM
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Originally Posted by ray2047 View Post
A bit confused by what you wrote. I believe you are calling the existing Square D the main but it isn't . The panel with the 200a fuses is your main. The SquareD is a sub panel.
Sorry for the confusion, I'm not surprised that my terminology is not quite right. If you check out the pictures in the Picasa album, you'll get a better idea of what's going on.

Right now the old 30 place SquareD is powered by the 200A fuse shutoff. Then from there the existing smaller sub panel is fed via a breaker. So the natural thing to do is what you cite below, just upgrade the wiring from 60A (or whatever it is) to 100A or so and power the new sub panel the same way.

Your simplest hook up is going to be from the SquareD panel. If you came off the 200 amp main panel you would have to use wire sized for 200 amp unless you could add a smaller size circuit to the box. That would get expensive and difficult size wire to work with. If the new subpanel is not in sight of the existing SquareD panel it will need to have a main breaker or 6 breakers or less.
I figured that would be some pretty fat wire and not cheap. The part that makes it not too bad though is that the new location for the sub is very close (see photos) it's only a couple of feet away, so the *cost* part wouldn't be prohibitive, though I was concerned about the difficulty of pulling that fat wire through even a short run of conduit that has a bend or two in it (I guess it'd just be one 90 degree bend).

Depending on the load on the new sub panel you will need either a 60 amp or possibly 100 amp circuit breaker in the original SquareD panel. If it is not four wire now it will need to be changed to four wires and four wires will need to be used for the new panel.
It's currently 60A, but part of the point of this project is to be able to add a dryer circuit (in the new LC since the old one that's staying is completely full), which'll be another 30A or so I guess, so I'm sure I'd want to upgrade to at least a 100A breaker *if* I go that route.

But it sounds like from your original comments that I *could* power this new LC directly from the fuses (which I now know to call main -- I suppose because it has the fuses that protect the whole house) just how the other LC is powered directly from them. That sounds more like the right solution to me because I'd have full 200A capability to this new LC rather than just 100A or so. It is a 40 place LC and it'd be nice to not be limited on future growth.

If you have a chance, take a look at the photo which is a close up of the main. How would I add new 200A wire to those existing lugs? I doubt they'd fit, so can I buy new lugs that have spots for two wires, or can you stack new single place ones on top of the existing ones?

The new wires would have to run out from the main to the left and around the corner to the position for the new LC.

Thanks for your quick reply!
 
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Old 04-10-09, 09:58 AM
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Maybe the pros know a code approved way to pull a second set of wires from the fuse box but generally unless the manufacturer states it on the panel you can't put two wires under a lug. If you really want to come off the lugs I would connect a short length of wire to each lug and pigtail to it but the pros have to comment on that.

Is the reason you feel you need a 200 amp feed to the new panel because you are adding up the breaker sizes. If so that is wrong. Total amps of breakers often exceed supply. What counts is actual load. Between the two panels you can't exceed 200 amps any way. I really think a 100 amp feed will be fine.

I made one mistake in my original post. Looking at the pictures I see they are all together so you will not need a main breaker in the new sub panel. Also because of the metal conduit you do not necessarily need a ground wire but I would suggest it.
 
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Old 04-10-09, 10:32 AM
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You may be able to get some stacked lugs and change the bottom lugs in your main disconnect to feed your new sub panel. Like these: midsouthelectronics.com, stacked electrical lugs lug splicer reducer turn prevent mechanical connectors
You will not find these at the big box store, you will have to go to an electrical supplier.

I did a quick look on the net and found a a Square D QO 125 amp breaker for about $80. I also found a 150 amp but they wanted about $350 so I wouldn't think that would be cost effective.

As Ray pointed out, 100 or 125 amp should be more than enough for most things you are planing to run. Unless your home is HUGE or you are running electric heat, you should be fine.

Here is my suggestion to you:
You can still use the new panel and feed it with 100 or 125 amp two pole breaker off the existing panel. (200 amps is the max you can feed that panel.) Run a new 1 1/2" or 2" EMT pipe from the existing QO panel to the new panel. The oversized pipe is so you can relocate any 15 or 20 amp lightly loaded circuits in the future from the old panel to the new panel. Any large loads put in your 200 amp panel, such as the electric dryer. Although the addition of a ground would not hurt, it is not required if using EMT.

BTW looking at your pictures it looks like you have a ground wire on the neutral buss in the 200 amp panel. This is not correct because it is a sub panel. You should install a ground bar and separate your grounds and neutrals.
 
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Old 04-10-09, 11:31 AM
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Originally Posted by Tolyn Ironhand View Post
You may be able to get some stacked lugs and change the bottom lugs in your main disconnect to feed your new sub panel. Like these: midsouthelectronics.com, stacked electrical lugs lug splicer reducer turn prevent mechanical connectors
You will not find these at the big box store, you will have to go to an electrical supplier.
Very interesting. I figured there'd be something like that.

I did a quick look on the net and found a a Square D QO 125 amp breaker for about $80. I also found a 150 amp but they wanted about $350 so I wouldn't think that would be cost effective.

As Ray pointed out, 100 or 125 amp should be more than enough for most things you are planing to run. Unless your home is HUGE or you are running electric heat, you should be fine.
We do actually have one electric furnace, but I'm almost positive it's running off of the existing QO LC, and thus would not impact our discussion.

Here is my suggestion to you:
You can still use the new panel and feed it with 100 or 125 amp two pole breaker off the existing panel. (200 amps is the max you can feed that panel.) Run a new 1 1/2" or 2" EMT pipe from the existing QO panel to the new panel. The oversized pipe is so you can relocate any 15 or 20 amp lightly loaded circuits in the future from the old panel to the new panel. Any large loads put in your 200 amp panel, such as the electric dryer. Although the addition of a ground would not hurt, it is not required if using EMT.

BTW looking at your pictures it looks like you have a ground wire on the neutral buss in the 200 amp panel. This is not correct because it is a sub panel. You should install a ground bar and separate your grounds and neutrals.
Thanks for the tip on this, I'd just noticed that when tracing the tied together ground and neutral on the main and then noticed it appeared they were connected in the 200A QO panel as well. I wasn't sure whether that was right. I guess that'll go on the list of things to clean up later.

I greatly appreciate your suggestions. I'm still curious as to why you don't recommend going for the stacked lug approach especially since you're recommending running new fat conduit anyway for the breaker feed approach.

Is the #1 or #2 wire that I'd need to run from the main really that difficult to work with even if I just have one 90 degree bend in the conduit? Or is there some other difficulty I'd run into? It seems like we've got two votes for going w/ the existing approach to power the new sub panel, but neither of you suggested that going straight off of the main was not possible... just wondering about the reasons behind your recommendations.

I don't mind spending a bit more money on equipment and time to set it up my way, if that's all I'm looking at as a difference.

Thanks guys.
 
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Old 04-10-09, 11:44 AM
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I just called one of the local electric supply places to check on their price for those stacked lug parts. I started explaining my situation in brief and the guy at the parts counter said it sounded like what I was proposing would not be to code.

His explanation was something along the lines that I'd be trying to double up the current through the 200A fuses (like I'd be trying to pull up to 400A through each hot or something). I didn't fully understand the explanation, but he seemed to be sure and I'm pretty sure he understood what I was trying to do.

This is exactly why I'm doing some research on this situation and asking so many questions -- I want to make sure that everything I'm doing at this level is to code and I'm not cutting any corners.

Anybody have thoughts on his explanation or could elaborate on it?
 
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Old 04-10-09, 03:37 PM
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If you are concerned about the amount of load from the dryer I would add it to the big panel and just move smaller circuits like lighting to the new panel.

If it were me I would just add a 2 pole to the big panel and feed a sub off of it.

The fused disconnect would see the same amount of current either way.
 
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Old 04-10-09, 08:08 PM
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Originally Posted by tgice View Post
His explanation was something along the lines that I'd be trying to double up the current through the 200A fuses
That would not matter because you will be on the load side of the fuses and no matter what, you will only be able to get 200 amps before they blow. It is the same as if you tried to pull more than 200 amps on your existing panel. You are not getting any more amps then you have now. You would have an issue if you tried to make your connection on the line side of the fuses which is NOT ok.

If you use the double lugs the wire you would need is 2/0 copper. If you fed it off a 100 amp breaker in the existing panel you would use #3 copper. The #3 is much easier to work with. The reason I said to use a breaker in your existing panel is cost and ease of installation. It would be easy to relocate circuits if needed to the other panel. You could run a couple large loads off the new panel but if your were adding more than that I would put them in the existing panel.

It's really your call as far as how much money and how much time you are willing to spend.
 
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Old 04-11-09, 12:30 PM
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That main is prettu old, albeit in good shape.

If it were me though, I'd replace the old main fuse/switch with a new main panel, leaving the exising primary (right hand) sub, and moving the other sub (left hand) circuits to the new mian, as well as some of the high powered loads.
 
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Old 04-12-09, 08:29 AM
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Originally Posted by classicsat View Post
That main is prettu old, albeit in good shape.

If it were me though, I'd replace the old main fuse/switch with a new main panel, leaving the exising primary (right hand) sub, and moving the other sub (left hand) circuits to the new mian, as well as some of the high powered loads.
Do you mean removing the left sub all together and replacing the right sub LC w/ a 40 space on (that I've got -- the right one is currently 30 spaces, I think)?

That probably still wouldn't leave me much room to grow, though. That was my original idea until the electrician showed up to give me a bid and talk me through the options. If I could have gotten something like a 50 place panel (which doesn't exist, to my knowledge), I might've gone that way. The other issue is I already have 4 conduits running into the left sub which would be difficult (for me) to relocate anyway.
 
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Old 04-12-09, 03:05 PM
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Originally Posted by Tolyn Ironhand View Post
That would not matter because you will be on the load side of the fuses and no matter what, you will only be able to get 200 amps before they blow. It is the same as if you tried to pull more than 200 amps on your existing panel. You are not getting any more amps then you have now. You would have an issue if you tried to make your connection on the line side of the fuses which is NOT ok.
See, that's what my original thinking was. I'm thinking about contacting my local code enforcement office and talking to them about it. Hopefully they'll be able to review the basics of what I'm talking about and tell me whether it'll meet code.

It's really your call as far as how much money and how much time you are willing to spend.
An extra $100 - 200 doesn't mean much to me, and neither does a bit of extra time. As long as I could knock this out on a Saturday or at most a full weekend, I'd be fine for me.
 
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Old 04-12-09, 06:37 PM
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Originally Posted by tgice View Post
See, that's what my original thinking was. I'm thinking about contacting my local code enforcement office and talking to them about it. Hopefully they'll be able to review the basics of what I'm talking about and tell me whether it'll meet code.
It never hurts to call and ask questions. For a trip fee you can sometimes have the inspector come out to take a look.
 
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Old 04-13-09, 05:56 PM
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Originally Posted by tgice View Post
Do you mean removing the left sub all together and replacing the right sub LC w/ a 40 space on (that I've got -- the right one is currently 30 spaces, I think)?
No, exchange the new panel you have (which is an MLO panel), for a 200A Main panel and replace the fused switch with it. Leave right hand sub there, feeding it with 100A from the new main panel, and move some of the heavy loads and the circuits from the left hand sub to the new main panel, as well as any new circuits you may desire.

You could set up a junction box or use the old sub panel as a junction box.

There is no such thing as a 50 circuit panel, since the code limit is 42.
 
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Old 04-14-09, 06:10 AM
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Originally Posted by Tolyn Ironhand View Post
It never hurts to call and ask questions. For a trip fee you can sometimes have the inspector come out to take a look.
I went ahead and called the office and outlined my scenario. The guys I talked to were helpful.

The electrical inspector told me that in order to hook both sub panels directly to the main I'd have to ensure that the wires hooking them both up were full 200A compliant (he said 3/0 copper, or [I assume] 4/0 aluminum). I think he was saying that the code allows you to have somewhat less than the full 200A capable hooking up a sub panel *only if* it's the only sub panel directly off of the main.

So I tried to take a look at the existing wires hooking up my first sub and, since they're totally unlabeled (from what I can see), does anyone have any pointers on how I can tell what gauge they are? I'm also not even sure if they're aluminum or copper. The wires that I can see in the lugs appear to be mostly silver, except the ends look somewhat copperish. Could they be copper w/ some sort of silver colored coating or are those mostly likely aluminum?

It also appears that the main-to-sub wires are the exact same as the meter-to-main wires.
 

Last edited by tgice; 04-14-09 at 06:30 AM.
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Old 04-14-09, 06:29 AM
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Originally Posted by tgice View Post
So I tried to take a look at the existing wires hooking up my first sub and, since they're totally unlabeled (from what I can see), does anyone have any pointers on how I can tell what gauge they are? I'm also not even sure if they're aluminum or copper. The wires that I can see in the lugs appear to be mostly silver, except the ends look somewhat copperish. Could they be copper w/ some sort of silver colored coating or are those mostly likely aluminum?
Looking at your pictures the wires seam to be the correct size. Wire size requirements have not changed much over the years, only the insulation has. It sounds to me like you may have aluminum wires. I have seen tin coated copper wires before but not in that size. If they are AL wires or you use Al wire be sure to use anti oxidation paste.

Originally Posted by tgice View Post
It also appears that the main-to-sub wires are the exact same as the meter-to-main wires.
That would be correct.
 
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