electrical question - 200amp subpanel from 200amp main?
#21
(08-24-2022, 08:39 AM)Roly Wrote: How are you connecting the sub panel to the main panel ? Is it rated for doing this ?  Does it have lug provisions on the main bus in the original panel ?  If it has aluminum bus in it I would not do it. A few questions for you electrican.  Roly

Indeed (questions for him)
My understanding of a sub feed lug block is that it snaps into the stabs (takes up 4 spaces) and looks like a breaker without a handle (as opposed to adding lugs to the main bus.)   Though options may be available in the form of a lug kit (the original panel has copper busses)

honestly the more I ponder this the more I'm shying away from the whole thing lol.
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#22
(08-24-2022, 08:44 AM)mound Wrote: Indeed (questions for him)
My understanding of a sub feed lug block is that it snaps into the stabs (takes up 4 spaces) and looks like a breaker without a handle (as opposed to adding lugs to the main bus.)   Though options may be available in the form of a lug kit (the original panel has copper busses)

honestly the more I ponder this the more I'm shying away from the whole thing lol.

 As I understand it the sub feed lug kit is for existing main lug panels .  Not to just plug into the bus on main breaker panels.   Another way to do it is to add a 200a breaker below the meter base and sub feed off of that.
Best have you electrician out to look at what you have and which way to go from there.  Roly
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#23
(08-24-2022, 08:54 AM)Roly Wrote:  As I understand it the sub feed lug kit is for existing main lug panels .  Not to just plug into the bus on main breaker panels.   Another way to do it is to add a 200a breaker below the meter base and sub feed off of that.
Best have you electrician out to look at what you have and which way to go from there.  Roly

I thought there were also lug "blocks" that position like a breaker would, but I'm not sure, will have to ask the expert.  
Interesting idea about adding a 200amp breaker below the meter base.  Wouldn't that though become the first point of disconnect and require then that the grounds and neutrals be isolated inside what was the original main panel? or perhaps I'm misunderstanding.
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#24
Hah.. re-reading my original post, I failed to mention a key point that this "200amp extension subpanel" I had in mind would replace an existing 100amp sub-panel that's already there but has too few slots to add the whole kitchen. 

The electrician just stopped over this morning and took a look and listened to my idea and said (while laughing) "clever, but your crazy.. let's just replace the 100amp sub-panel you have with a newer one that has more slots and you'll be good to go..  don't need more capacity just more slots and a cleanup"


I always overthink and overbuild things.. I don't know if it's a blessing or a curse!
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#25
That does shift things a bit.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#26
I agree with your electrician.

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#27
so to add to this... continued brainstorm  (my guy went on vacay but I'll ask him as well, I don't think this is as insane!)

I've spent some time doing load calculations, not just the generic kind but actually putting ammeters on all the different things to see what they really draw (workshop going full bore, say, during the summer with AC running and the pool with its huge heat pump and robot vacuum cleaner all while we're putting the new kitchen to full use during a party with people in the hot-tub. etc.. thinking about "how much will this house really draw if certain things that could all be on at once were.." 

the 200amp service I think would just handle all that.. today..  but what if I add welding, or or an EV charger, or a much larger hot tub..  I plan to be in this house 20 years..  I think it's possible that looking into a 400amp service upgrade sometime down the line may be in order. 

so with that in mind.. if replacing the existing 100amp sub-panel is going to happen anyway, why not just replace it with a 200amp panel - rated for 200amps, but keep it at 100 today (ie. existing 100amp breaker in the main and feeder to it.)

Then, IF I ever did a 400amp upgrade, this could easily turn into a 200amp subpanel.

Any reason not to upsize the sub-panel's rating today even if I don't use it to its full capacity?
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#28
That would be a reasonable idea.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#29
(08-26-2022, 07:27 AM)mound Wrote: Any reason not to upsize the sub-panel's rating today even if I don't use it to its full capacity?

None at all, but you may still have a problem finding that 200 amp breaker to feed it in the future (as a subpanel). But you can cross that bridge later.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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#30
Quote:so with that in mind.. if replacing the existing 100amp sub-panel is going to happen anyway, why not just replace it with a 200amp panel - rated for 200amps, but keep it at 100 today (ie. existing 100amp breaker in the main and feeder to it.)

Then, IF I ever did a 400amp upgrade, this could easily turn into a 200amp subpanel.

Any reason not to upsize the sub-panel's rating today even if I don't use it to its full capacity?


You seem to be overthinking this / suffering from analysis paralysis. Perhaps to save a bit of dosh, but it's a fool's errand.

1. your immediate need seems to be ( though this changes when you reveal more layers of your onion) that you need more breaker spaces in your subpanel .

Easy enough - get a new 100A sub panel with 40 or 42 spaces.   It's the cheapest option by far.   A Square D , QO series can be sub panel or a main panel with a knockout removed and the addition of a main breaker.  It can be configured 100A or 200A or any other capacity they make main breakers for.  Doesn't matter for you since you'll be feeding it from your main panel (or outside if you go that route in the future)  You'll be covered whatever you do -or- don't.

2. But wait............................"what if"..............................:
I get a charger  ?
-or- a welding rig ?
-or- decide to power the neighbor's outdoor fridge ?

Salient point that.    But you really should decide NOW how likely that scenario is.   If more likely than not, bite the bullet and upgrade your service now.   It will not be cheaper in the future and the money you'll use to pay for it will become more expensive in the future as well.

Based on what we've heard of your house and loads, 200A is already pushing the limit.  An upgrade seems inevitable if you add anything like a welder or high amp car charger.    You could inquire about 320A service. It's often a lot cheaper than 400A when available.  That should give you enough headroom given what we've heard ..............so far 
Sarcasm
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