Understanding Critical Loads - E
Version 1.0 160808 | Subject to change.
Understanding Critical Loads
There are a few important •Max Running Wattage. This is the average sustained power that an
items to consider when electrical load consumes while operating.
estimating critical loads •Starting Wattage. When devices with inductive motors are powered on,
for your battery energy they will briefly draw initial current and power (“surge”) that is higher than
storage system: their Running Wattage. For example, a refrigerator with a compressor will
switch its compressor on and off continuously to maintain temperature.
The appliance’s “Power/Ratings” will generally include the maximum
Starting Wattage information.
•Run Time. This is the time that a load is drawing power (powered on).
What are critical (essential)
electrical items needed
during an emergency grid
power outage?
NOTE
These wattage worksheet instructions focus on determining your estimated total wattage requirements that
prevent or minimize nuisance power trip events during a power outage. Nuisance power tripping occurs when
instantaneous power demand exceeds the peak power output capabilities of the energy storage system.
Generally, greater battery capacities allow a greater number items that can be powered on simultaneously, as
well as allow for longer periods of running time during a grid power outage.
crit·i·cal
adjective
of decisive importance with respect to the outcome; crucial.
Since your home will still be grid-connected with battery backup (and you are not going completely off-grid), it is
possible to install a battery that is relatively small and affordable. First, it is necessary to determine what items in
the home are most critical to keep powered, when a power outage occurs. The battery system will not be able
to provide or sustain all the power needs of your home during a power outage, so it is necessary to plan for the
amount of energy that is absolutely necessary during these critical events.
There is a technical limit on the amount of power that can be drawn from battery systems during a grid outage.
These ratings are listed in the chart that follows. The length of time that the batteries can supply power to critical
loads during an outage is based on the amount of energy being used and how much battery capacity
is available.
more information at: e-gear.us
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E-GEAR™ Battery Energy Storage Systems have the following
maximum power ratings, based on kWh battery capacity installed.
Maximum Power Ratings
System Size
Max Output Wattage
Max Surge Wattage
(30 Minutes)
Max Surge Wattage
(3 Seconds)
6.4 kWh Capacity
3,000 Watts
3,000 Watts
3,000 Watts
9.6 kWh Capacity
4,500 Watts
4,500 Watts
4,500 Watts
12.8 kWh Capacity
5,000 Watts
6,000 Watts
6,000 Watts
16 kWh Capacity
5,000 Watts
6,000 Watts
7,500 Watts
19.2 kWh Capacity
5,000 Watts
6,000 Watts
8,500 Watts
The energy component (consumption) of an appliance is also based on its individual run time. For example,
a 800W microwave running at 100% power for 3 minutes consumes roughly the same amount of energy as a
40W light bulb for an entire hour of operation.
Critical Loads Worksheet Instructions
Step 1 Determine the critical items you wish to power simultaneously.
Choosing items
for a critical
load circuit and
managing its use
is a matter of
prioritization and
budgeting power.
It is best to get the information directly from the actual appliance you intend to
use, but you can also refer to the following chart to assist in estimating this
information. Fill-in the running watt and starting watt requirements on the
“Critical Loads Worksheet."
Step 2 For load items that don’t have a higher Starting Watts value, use
the Running Watts as the Starting Watts value.
Step 3 Add the Starting Watts values for the critical load items you want
to power. This will provide the total of these items’ peak power requirement,
when used simultaneously.
Step 4 Add the Running Watts of the critical load items you wish to
power. Enter this number in the Total Running Watts column. This is the
sustained power requirement to support all of these devices at one time.
Step 5 Choose the higher of the two values, "Starting Watts"
and "Running Watts", and enter it into the box labeled "Minimum Power
Requirements". If this value is larger that the "Max Output Wattage" in the row
of your selected battery size in the "Maximum Power Ratings" table above,
you must do one of the following:
• Remove one of more Critical Load Items.
• Choose a larger-capacity battery size.
more information at: e-gear.us
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example:
to use the easy critical loads calculator go to: e-gear.us/criticalloads
FAQs
Q: How many watts does it take to power basic items in an average size house?
A: In a typical home, essential items will average 3000 – 5000 watts of power to run. To run the entire home will
require much more power than is practical for a standby/backup battery energy storage system.
Q: What is the difference between running watts and starting watts?
A: Running, or rated watts are the continuous watts needed to keep items running. Starting watts are extra
watts needed for two to three seconds to start induction motor-driven products like a refrigerator or circular saw
— this is the maximum wattage the system will be loaded with.
Q: What if I can’t determine the running or the starting watt requirement for an appliance?
A: If the running watts are not on the appliance, you may estimate using the following equation:
WATTS=VOLTS x AMPS. Only motor driven items will require starting watts. The starting watts required may
also be estimated at 1-2x the running/rated watts, but may be as high as 7x.
Q: What happens if I do experience nuisance power tripping?
A: The energy storage system will automatically reset after a short period of time and reattempt to meet the
power requirement. You my need to reduce the power requirement by turning off some devices to prevent
further power tripping events.
more information at: e-gear.us
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Wattage Estimates
Storm / Emergency Use
Starting
Watts
Running
Watts
Essentials:
Starting
Watts
Running
Watts
Laundry Room:
Incandescent Light Bulb-60 Watt
60
60
Iron
1,200
1,200
CFL Light Bulb-60 Watt Equivalent
15
15
Washing Machine
2,250
1,150
LED Light Bulb-60 Watt Equivalent
Refrigerator/Freezer
8
8
Clothes Dryer-Electric
1,350
5,400
2,200
700
Clothes Dryer-Gas
1,800
700
Refrigerator/Freezer-Energy Star
1,200
200
Electronics:
Sump Pump-1/3 HP
1,300
800
AM/FM Radio
100
100
Sump Pump-1/2 HP
2,200
1,050
Stereo Receiver
450
450
Water Well Pump-1/3 HP
1,400
750
CD/DVD Player
350
350
Water Well Pump-1/2 HP
2,100
1,000
TV-Tube Type
300
300
Electric Water Heater
4,000
4,000
TV-Flat Screen-20"
120
120
TV-Flat Screen-46"
190
190
40
40
Heating/Cooling:
Space Heater
1,800
1,800
X-Box, PlayStation, Wii, etc
Humidifier-13 Gal
175
175
Cell Phone Charger
25
25
Furnace Fan-gas/oil-1/8 HP
500
300
Computer-Laptop
250
250
800
800
30
30
600
600
500
500
Furnace Fan-gas/oil-1/6 HP
750
500
Computer-Desktop
Furnace Fan-gas/oil-1/4 HP
1,000
600
Monitor (LCD)
Furnace Fan-gas/oil-1/3 HP
1,400
700
Printer
Furnace Fan-gas/oil-1/2 HP
2,350
875
Home Entry:
Window AC-10,000 BTU
1,800
1,200
Window AC 12,000 BTU
3,950
3,250
Garage Door Opener-1/4 HP
1,100
550
Central AC-10,000 BTU
2,200
1,500
Garage Door Opener-1/2 HP
1,400
725
Central AC-20,000 BTU
3,300
2,500
Personal Care:
Central AC-24,000 BTU
4,950
3,800
Hair Dryer 1250 Watt
1,250
1,250
Central AC-32,000 BTU
6,500
5,000
Power Tools:
Central AC-40,000 BTU
7,800
6,000
Hand Drill 1/4"
350
350
Heat Pump
4,500
4,700
Hand Drill 1/2"
600
600
200
200
Portable Box Fan-20"
Kitchen:
Home Security System
Circular Saw 6-1/2"
500
500
Circular Saw 8-1/4"
1,400
1,400
1,800
Microwave Oven-650 Watts
1,000
1,000
Table Saw 10"
6,300
Microwave Oven-800 Watts
1,300
1,300
Band Saw 14"
2,500
1,100
Microwave Oven-1000 Watts
1,500
1,500
Air Compressor 1/2 HP
3,000
1,000
Coffee Maker-4 cup
Electric Range-6" Element
600
600
Air Compressor 1-1/2 HP
8,200
2,200
1,500
1,500
Quartz Halogen Work Light, 1000
1000
1000
Electric Range-8" Element
2,100
2,100
Submersible Pump 400 gph
600
200
Electric Fry Pan
1,500
1,500
High Pressure Washer 1/2 HP
3,150
950
Electric Grill (tabletop)
1,650
1,650
High Pressure Washer 1 HP
6,100
1,600
270
270
900
900
Dishwasher-Hot Dry
1,400
1,450
Dishwasher-Cool Dry
1,400
700
850
400
1,200
1,200
850
850
Blender
Toaster Oven
Toaster
more information at: e-gear.us
Wet Dry Vac 1.7 HP
NOTE
Slow Cooker
These wattages are estimates only. You should
always check your appliance for exact wattage requirements. For exact wattages, check the data plate
or owner’s manual on the item you wish to power.
4
My Critical Loads Worksheet
EXAMPLE
Starting
Watts
APPLIANCE OR TOOL
1. Energy Star 25.4 cu. ft. Refrigerator
Running
Watts
73
1800
2. Television
500
500
3. Microwave Oven-800 Watts
625
800
4. Incandescent Light Bulb-40 Watt x 4
160
160
5. AM/FM Radio
100
100
6. Security System
500
500
50
50
1150
2300
3158
6210
7. Cell Phone Battery Charger x 2
8. Automatic Washing Machine
9.
10.
TOTALS
PEAK POWER REQUIREMENT (WATTS)
Larger of "Starting Watts" and "Running Watts"
6210
MY CRITICAL LOAD POWER NEEDS
Starting
Watts
APPLIANCE OR TOOL
Running
Watts
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
TOTALS
PEAK POWER REQUIREMENT (WATTS)
Larger of "Starting Watts" and "Running Watts"
more information at: e-gear.us
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ALTERNATE PLAN
MY CRITICAL LOAD POWER NEEDS
APPLIANCE OR TOOL
Starting
Watts
Running
Watts
Starting
Watts
Running
Watts
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
TOTALS
PEAK POWER REQUIREMENT (WATTS)
Larger of "Starting Watts" and "Running Watts"
ALTERNATE PLAN
MY CRITICAL LOAD POWER NEEDS
APPLIANCE OR TOOL
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
TOTALS
PEAK POWER REQUIREMENT (WATTS)
Larger of "Starting Watts" and "Running Watts"
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