# How much power off a 20 amp breaker?

I am currently remodeling by bonus room. The way it was built before 5 outlets and 2 wall mounted lights, window a.c unit , and a wall mounted space heater. I gutted the whole room down to the studs and ran new cup light off the main feed and ran a new line with a new 20 amp breaker ( keep light and outlets off same breaker) my ? Is I want to put a ductless heating and cooling in there can I run the power off the new feed? The things that will be on it will be 5 grounded outlets and want to put 110 volt ductless heating/ air system?

 21boat Posts: 2,419, Reputation: 1103 Ultra Member #2 Jan 13, 2009, 01:43 PM

Here is a base chart of wattage usage to calculate your room usage and you can go from there
They way the wattage works is your only supposed to use 80% of the available wattage in the lines for the safety margin/breaker
So a single 20mp is 120x20 = 2400 watts. The usable is 19200 watts.
A baseboard heater is 250 watts per lineal foot.
I don't know if a permit was pulled hear but check on your local codes on outlet placement of how many per wall run. Here's its within 2 foot of a corner and every 6 foot
14 gauge / 15 amp = 1,440 usable watts ( 80% of 1,800 watts in the line)
12 gauge / 20 amp = 1,920 " "
10 gauge / 30 amp = 2,880

defines as 3 watts per ft square for for lighting and a duplex outlet be considered as 1.5 amps of load. The electrical requirements of HVAC equipment is also over estimated. Motors are computed at their worst case amperage, regardless of their actual load or usage patterns. The largest motor is assumed to draw 125% of it's running load.

So try to balance tour loads and I personally like to keep the lights separate or some of them separate from the outlets that way you pop a breaker in a branch circuit but still have lights to see

Signed 21 Boat

 stanfortyman Posts: 5,200, Reputation: 1401 Electrical & Lighting Expert #3 Jan 13, 2009, 02:35 PM

21boat, where are you getting these codes?

The 80% limit is for a single cord and plug load. The whole circuit is not limited to 80%.
See NEC T210.24

Within 2' of a corner and every SIX feet?? I know a few guys from Pa and I've never heard this one. Could it be every isolated wall space 2 feet or more, and no point along a wall shall be 6 feet from a receptacle? Just like the NEC?

Also, receptacle are NOT considered a 1.5 amp load in a residence. For a residential load calculation general use receptacles are already counted in the 3 watts per sq/ft calculation.
See NEC 220.14(J)
Commercially they are figured at 180va per device.
 stanfortyman Posts: 5,200, Reputation: 1401 Electrical & Lighting Expert #4 Jan 13, 2009, 02:36 PM

Nate, what is the electrical rating of this unit?
 natehook1 Posts: 3, Reputation: 1 New Member #5 Jan 13, 2009, 08:44 PM

Not sure if this is what you mean I just got this from the web 13SEER 9000Btu/h - Cooling & heating - 115V/60Hz/1Ph
In the specs only thing I see for rating is the rating current which is A if I am correct. Acfactoryoutlet.com is the web page it's a Klimaire KSWM009-H113
 stanfortyman Posts: 5,200, Reputation: 1401 Electrical & Lighting Expert #6 Jan 14, 2009, 05:31 AM

If you go to the page for that unit you see a specifications link. There you'll find the rated current which is 7.5 amps.
A fixed in place appliance that shares a circuit with not fixed in place items can draw up to 50% of the circuit. You are fine at 7.5A on your 20A circuit.

I must say, if it were me I'd run a dedicated line to this unit simply to keep the load off the other receptacles, but it is not mandatory by any means.
 hvac1000 Posts: 14,548, Reputation: 2381 Heating & Air Conditioning Expert #7 Jan 14, 2009, 05:35 AM
A dedicated line sure does make it easier for the unit to start since there will be no other load on that line at any time.

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