Easy Question Regarding Breaker Box Capacity

[madpenguin]

According to the Black and Decker book, we want #6 to run 60 amps (from main breaker to sub panel) so I think I will go with this to be safe.

They are talking about NM-B cable (romex) and that would be correct. It's actually rated at 55A but the NEC allows you to step up to the next size breaker since there is no 55A breaker. Individually run THHN conductors in conduit has a greater ampacity. #6 THHN is rated at 75A. #8 THHN is rated at 55A. Were it me, I'd pull #6 as well and protect it with a 60A breaker.

I'm sure you ran 1/2" ENT however and that posses a problem. You would need 3/4" ENT or EMT if you ran #6. No more than 360 degrees worth of conduit bends between pull points and no pulling of conductors thru an "unfinished" run of conduit.... I'm just telling you code related requirements if your interested. Good luck pulling 3 - #6's and 1 - #10 down a 1/2" conduit. Not only will it be very hard, but ampacities are also affected with increased conduit fill.

Really, the conduit idea was a good one but way overkill. If all of this is taking place in an unfinished basement (exposed ceiling joists), then you are allowed to staple/cable-clamp an 8/3 romex or a 6/2 romex to the underside of the joist along with anything larger. Your 10/3 could have been ran in holes drilled thru the joists had you used romex....

However, if you think it's OK to keep my #10 ground (green) from main breaker to sub panel then I will not mess with this one.

Yes. The NEC allows this per 250.122.... Even with #6 hots/neutral.

I did use the double-pole 240v breaker in my main circuit box as pictured in your image above. Mine says "30" on each side of the connected pole (just like the one in your picture). However, as I understand it this is still only a 30 amp 240v breaker and I need one marked "60".

That is correct but only if you pull new feeder conductors to your sub. Currently, you have the correct breaker for the #10 that you ran.

I will upgrade this to the same style but with a 60 amp trip capacity and upgrade all wires to the sub panel except for the grounding wire. This will allow me to use all 20 amp 120v receptacles to their full capacity if I need.

That's correct. Just make sure you pull #8 or #6 THHN (the red,black and white) for 60A capacity. The green #10 can stay.

As for your existing house load and your main being rated @ 100A, I don't think any of us here knows what the load demand is for your house. You could have a gas stove, gas water heater and a gas furnace. For all we know, your average amp draw excluding the new grow room could be 20A for lights, TV and an always on computer.

I have a 60A service and run a total of 3.5KW worth of lighting along with a window AC unit and a dehumidifier plus my kitchen fridge. I think you'll be OK on your 100A service.... Now if you have an electric stove, dryer, furnace, water heater or any combination thereof, you might be tripping your main when your lights are on.

 

[madpenguin]

I'm still a tad worried about how much your ballasts draw. Is there anyway you can post the nameplate specs of them? eg - what amperage @ what voltage?

 

[LlamaSchool]

All my appliances are gas except for my fridge. I have one small television and a few laptop computers as well as a couple oscillating fans in the summer. Will photograph nameplates when I'm back at the house later this week.