Recently moved and the new place has a sub-panel connected to a generator 30A inlet via 10# wire.  I asked what the procedures for use were and the guy I asked while walking through the house didn't know.  Not how I would have preferred to have wired it, but the city signed off on it so must be OK.

The sub-panel contains the circuits to be fed by generator.  These circuit are not duplicated on the other panel FYI.  The circuits on the sub panel are fed from the main panel while the utility power is on.  As far as I can tell the procedure would be:

To use generator:
1.  Move 50A breaker on main panel labeled emergency panel from on->off.  That circuit should be in the off position to use generator, thus isolating the main panel (and the outside utility) from generator power.
2.  Move interlocked sub-panel 30A circuit to from right to left.  Since the metal bar ties those two 30A circuits together moving the bar will cut the feed from the main panel (on left) off and the feed from the generator (on right) is turned on.
3.  Now generator is feeding circuits on sub panel and the main panel is isolated from generator power.

Next question:
Since there are 2 hots coming from the generator I'm assuming I need to run the generator in 240V mode?  Do those 2 hots provide 120V to both sides of the panel?  Just need to make sure I understand how to configure the generator before I test things out for the first time.

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It's fine.

Wiring is too neat to work properly.  Electrons will be very confused. 

As long as you do not take off the interlock it is perfectly fine but you are stuck with only what is in the sub panel.

Yes you do need to feed in the 240v to power each side of the panel.

I do not advise doing this but in the event of an emergency you can remove the interlock and you can power any of your circuits in either panel by turning on both of those breakers which will feed power back into your main panel.

The reason I do not advise doing that is because you need to make sure the feed to your main panel is off and if you screw it up you can kill somebody, that is why there are safety interlocks. The other reason there are interlocks is because most generator inlets are male. If you happened to have the interlock removed and you had that generator inlet breaker turned on when the power was still on from the grid you could stick your finger right onto that male generator inlet and kill yourself.

Thanks all for the replies

Would a 7200W generator be the largest this configuration could handle?  240V x 30A circuit = 7200W

Is 7200W the most the 10# line from the generator to the panel could handle?  How would this configuration do hooked up to a 7500W generator with a 30A outlet?

It is going to be 30 amps PER LEG. Depending on loads in the house, you could have a bunch of 120v stuff on one leg and that trips while the other leg isn't drawing much power. With the attention put into that setup, I doubt that would happen unless you started plugging in space heaters.

Realistically, you won't be buying too big of a generator for that setup unless you have a rather fat wallet. You don't want to pay for fuel for a huge generator. I think you would be well served with a 9-10k surge load generator if you want maximum convenience.

As pointed out the bigger the generator you get the more money it will cost to run in most cases.

On the other hand look at it this way, you could have a 1MW generator hooked into that inlet but you are only going to get 30A out of it before it trips the breaker in that particular setup.

Agreed.  The gen inlet to panel line is the weakest link in the system.  Everything else could be improved easily by changing out some breakers, but running a new inlet line is more involved.

its a shame they ran that small of wire.

AFA what they wired the sub panel for

I see the other side has the freezer- might be more important than the bath lights

Looks like your whole house is electric, so a bigger gen with a optional direct connect to the a/c, water heater or dryer might be a consideration.

I am guessing the sub panel is 100 Amp rated. You could feed it with 100 amp and do a 50 amp inlet or larger in a hour if you bought a larger generator.

Reviving this thread, got side tracked with other projects.

Noticed this today on my inlet receptacle

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It's a female plug which should be male IIRC.  Having it wired this way is, at a minimum, unsafe.  I've looked briefly to see what NEC says about it but no luck.

Pretty sure this is wired wrong but should be pretty easy to fix.

i am not sure why you turn off the 50 amp main panel breaker , the interlock will cut the line power when you flip to generator power, you never want both on at the same time, so do not tamper with the interlock, having the line power on and the generator connected and on will result in fire in the generator.  flipping the 50 amp breaker then flipping the 30 amp breaker on the same line seems redundant.  i use a similar transfer panel made by gen tron.  it is ul rated and good for 100 amps, used heavier than #10 wire to install mine but for a very short run it may work ok.  i feed my panel off a 10 kw generator with a 25 foot #10 cord have had no problems and the cord never gets warm after 5 hours. now a braided wire cord is usually equal to one solid wire size larger so a #10 cord should be equivalent to a #8 solid wire.

not sure why you would worry about the #10 wire running between the panels it seems to be working fine, it is not in service when the generator is on so is inconsequential for generator use.

yes should be a recessed male on the generator inlet side of the panel , make up a cord with male and male plugs keep the generator breaker off when you connect, or connect the cord before starting the generator.the receptacle on the panel will never be hot as the interlock will prevent line power feeding through the receptacle,  the plug on the cord will only be energized if you run the generator with the generator breaker on and cord connected so make sure you are connected up before generator start. as far as that foam on the receptacle just cut it of with a razor blade knife.

I just got over having no electricity from the nor'easter here. We lost power last Wednesday at 7 pm and got it back Sunday at 2 pm.

Test your system out! Fire the generator up and see how it works and get comfortable with the circuitry in the house. Maintain your generator. Keep a stock of fresh gas. Test your system out. Keep oil on hand because if you have an extended outage like I did during Sandy, 11 days, you'll need to change the oil. Don't forget to test your system out!

Yes, your generator input receptacle should be a male. This is so you are using a standard male/female cord, not using an "involuntary manslaughter" cord.

Can anybody find something official saying that?  NEC etc?  If I can find something the warranty I bought with the house says they will come fix it.

406.6(B) Connection of Attachment Plugs. Attachment plugs
shall be installed so that their prongs, blades, or pins are not
energized unless inserted into an energized receptacle or
cord connectors. No receptacle shall be installed so as to
require the insertion of an energized attachment plug as its
source of supply.

Just fix it yourself and be done with it.

I would have used 6g to wire it definitely not 10g.

Be careful to not overload the wiring.

Looks like you nailed it!

I like that you have two shut offs from main to sub panel.

10ga is rated to 30 amps, assuming no long runs. That would make that 220v output at 30x2 amps (30 amps on EACH conductor) max capacity (not including surge, assuming not used for heating circuits which reduced capacity).

6ga conductor is rated to 55 amps. Only needed if you had your generator hundreds of feet from your input.