Sub panel for my garage rennovation

I currently have a 200 amp main panel and a sub panel in an attached garage protected by a 60 amp breaker. I am setting the garage up for a metal working (hobby) shop. My loads (not all running simultaneously) in the garage will be as follows:

54 FLA @ 240v 3ph 10 hp phase converter [(10 hp x 743 / 240v) x 1.73]*
25 FLA @240v 1ph air compressor
125 FLA @ 240v 1ph welder **
30 FLA @240v heating/cooling
* = not sure if this is the proper way to calculate the draw for a rotary phase converter.
** = FLA @ 100% duty cycle & 100% output power on this machine. I will never come close to utilizing this and will probably put the machine on a 60 amp breaker.

So I need to upgrade the garage's sub panel and would like to go to 200 amp so it won't be an issue if I want to weld, have the AC on, and have the air compressor kick in all at the same time. Adding a second meter isn't an option. What I would like to do is get a subfeed lug kit for my main panel and run aluminum wire 4/0 4/0 4/0 #6 (ground) from the subfeed lug on the 200 amp main panel to a new 200 amp sub panel. Is this the correct way to do this via code? The feeder to the sub panel would technically be protected by the 200 amp main breaker on the main panel. The sub panel would also have a 200 amp breaker on the feed at the top of the panel for a local disconnect. The sub feed lug kit available for my panel is rated for 225 amps and the the wire should appropriately sized for 200 amps and at 150' will have a voltage drop of ~3.5%.

Anything I'm missing? I'd hate to spend $1.5k on materials to find out come inspection that this isn't allowed.

do you have working room in your existing panel for the 4/0 and do the subfeed lugs accept 4/0? Is the #6 ground copper?

another problem is that most main panels don't allow full load current on feed through.in other words a 200 amp main will only allow 125 amps feed through.read the label on main panel.if this is what you find,your only soulition is a 400 amp main panel.200 amp fo house and a 200 amp main for garage.

oleguy said:

another problem is that most main panels don't allow full load current on feed through.in other words a 200 amp main will only allow 125 amps feed through.read the label on main panel.if this is what you find,your only soulition is a 400 amp main panel.200 amp fo house and a 200 amp main for garage.

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not necessarily. For example Square D Homeline has a 225a subfeed lug kit, but it eats 4 spaces. I think any subfeed lug kit or 200a breaker for a residential panel is going to take 4 spaces.

What make / model is the panel?

you are correct that the feed through takes 4 spaces but like i said most wont let you feed through at full load rating.

oleguy said:

you are correct that the feed through takes 4 spaces but like i said most wont let you feed through at full load rating.

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the homeline 4 position subfeed lug I mentioned is rated for 225 amp. I just checked murray and they too have a 225 amp rated subfed lug. I think the other manufacturers will as well.

oleguy said:

you are correct that the feed through takes 4 spaces but like i said most wont let you feed through at full load rating.

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Most panels I've seen only allow 125 amp or so from two buss stabs, if these utilize 4 breaker positions I have no reason not to believe that the ampacity would be doubled.

Secondly, the manufacturers make their own subfeed lug kits. If it says it's rated for 225 amps, I'd be inclined to believe them.

It's a Cutler Hammer 42 breaker box (new in the past 3 months), I don't see a model # on the label. The label says max 200 amp per stab. It also gives the part number for the 225 amp sub feed lug kit on the label, as well as the part number for larger gauge neutral/ground bar clamps.

jkeyser14 said:

It's a Cutler Hammer 42 breaker box (new in the past 3 months), I don't see a model # on the label. The label says max 200 amp per stab. It also gives the part number for the 225 amp sub feed lug kit on the label, as well as the part number for larger gauge neutral/ground bar clamps.

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So is what i'm proposing ok?

jkeyser14 said:

So is what i'm proposing ok?

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If you use the C-H parts there should not be a problem.

Charles