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Garage sub panel question
- Thread starter qpoonz
- Start date
Is that the main with a subfeed of the same size to the house? You say it is a subpanel, but that doesn't really make sense from what is shown there. Anyhow, yes, you should be able to put a double-pole 30 amp breaker in there, but whether or not you actually have the power for it is a different question. A 125a feed really isn't a hell of a lot for a house, particularly if you are diverting up to 45 amps from it (the "garage" breaker, plus the new one).
Yeah Like rives said .... that looks like the Main panel & your house has a subpanel somewhere . go to the panel in the house & add up the breakers that are in it . if they amount to more than 125 amps .... you may not have enough power to add more circuits without tripping the main .
I don't know how you are determining your level of usage, but yes, it's likely that you could use your lighting when the dryer is off. You can't really just total up your breakers to determine the connected load. For instance, my house has a 42-circuit 200 amp main load center which is full of 15-30 amp single pole breakers, as well as a large selection of double pole breakers ranging from 30 to 100 amps. If you totaled everything up, I would probably need a 600 amp main to handle it all. The actual usage factor on each circuit is extremely low to non-existent.
Right again rives .... i had him look just to get a basic guideline of what he has in the house for circuits . by no means is it an actual usage factor . just an idea of whats being used in the house .
from the sounds of it .... yeah just add a 30amp 220 volt circuit to the garage for your grow . if your going to use one of the main lighting controllers with a 30 amp plug . your going to need a 4 wire recepticle .... one with a neutral wire added to it for 110 volt outlets & the timer in them .
If it is a sub panel make sure to separate the ground and neutrals to different lug bars. On a primary service they go to the same ground bar but on a secondary feed they need to be separated. Just wanted to add that even though your mlc needs no neutral.
N-P-Kali
Active member
What Rives is referring to is power factor. This is the relationship between the rated ampacity of a conductor (feeder wire) and how much load you actually draw at full load. With any motor, similar to your dryer, the manufacturer provides a technical specification sheet with data that describes each motor's performance in watts, FLA (full load amps), and recommended breaker size or minimum circuit ampacity.
For example a Split A/C with a performance of 18k btu @ 1∅ 230v has a draw of 9 - 11 amperes, but a recommended breaker size or minimum circuit ampacity of 20 amperes. That means while operating at full load the appliance is drawing 9 -11 amps maximum. The 20 amp circuit breaker is overload protection for the feeders (#14awg THHN) not the motor that is drawing current and should not continuously supply electrical current at excess of 80% (16 amperes) power factor.
A safe power factor is 80% on any single phase and three phase service. With a 125 amp service, 100 amps of current is what you can draw safely.
In conclusion my recommendation would be for you to do a little home work and add up the Full Load amps for all the appliances in your household, then take that figure (number) and divide it by your 125 amp service capacity. ex. 80a/125a=.64 or 64% meaning you can increase your load by and additional 16% or 20 amperes safely.
Hope this makes sense. Good night and Good luck.
You have incorrectly used the term "power factor" here. Although the definition of power factor refers to "real power" vs "apparent power", it has nothing to do with how heavily loaded a given circuit is. What they are referring to is the inability of a standard wattmeter to accurately read the usage on an installation with either a leading or lagging power factor. Reactive loads (heavily inductive or capacitive loads) distort the relationship between voltage and current - at unity, or 100% power factor, these two components overlay each other if you look at the sine wave for A-C. Reactive loads make these two components separate, and the difference between them becomes waste heat.
A standard wattmeter fails to bill the consumer for this waste heat, and it becomes a burden on the utility - they have to provide the power wasted, but they don't get compensated for it. Industrial installations have additional equipment to meter the power factor, and they then have to pay a penalty for this "hidden" usage. Reactive loads are such a small component in residential installations that they don't bother metering it, although I think the new smart meters are capable of measuring it.
http://en.wikipedia.org/wiki/Power_factor
N-P-Kali
Active member
Rives you are correct. I did use the term "power factor" incorrectly. Power factor is the real power divided by the product of the effective voltage and the effective power; PF = cos∅ = P/VeIe=P/S, where S=VeIe, meaning power factor is also the cosine of the phase angle between the voltage and the current. Thank you for the correction. Also I do believe your assumption about the new smart meters are correct as well.
IMHO that is in fact a sub panel fed from ur main panel. Look outside where the meter is and see what ur main breaker is, most likely it's a 200 amp main breaker. If it is just slap the 30 amp 2 pole breaker in the sub panel with proper sized wire and ur done, this isn't that complicated.
