TABLE OF CONTENTS - Snohomish County PUD

TABLE OF CONTENTS - Snohomish County PUD
TABLE OF CONTENTS
GENERAL INFORMATION
How to select a portable generator
What can happen if the generator is not used properly?
Can back feed also damage the generator?
How can I prevent back feed?
Will throwing the main breaker create the same result as a transfer switch?
Are there other safety tips to keep in mind?
CONNECTIONS
Permanent portable generator systems
Temporary portable generator systems
PUD Service Territory
PUD Contacts
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Everett (Headquarters)
425-783-8272
2320 California ST | Everett, WA 98201
Arlington PUD office
360-435-7500
210 E. Division | Arlington, WA 98223
Monroe PUD office
360-794-3900
120 E. Fremont | Monroe, WA 98272
Snohomish PUD office
360-563-2200
807 Rainier | Snohomish, WA 98290
South County PUD office
425-670-3200
21018 Hwy 99 | Edmonds, WA 98026
Stanwood PUD office
360-629-5700
9124 - 271 ST NW | Stanwood, WA 98292
PUD Real Estate Services 425-783-4408
1802 - 75th ST SW | Everett, WA 98203
Other Utilities
Telephone:
Verizon
Gas:
Puget Sound Energy
Cascade Natural Gas
Water:
Contact your local provider
Cable:
Contact your local provider
Electrical Inspections
Monday through Friday, 8:00 am to 5:00 pm
Toll-free in Western Washington and outside the
Everett local calling area at 1-877-783-1000
State of Washington L&I (Everett)
425-290-1309
State of Washington L&I (Mt. Vernon)
360-416-3000
City of Mountlake Terrace
425-775-9694
City of Everett
425-257-8810
PORTABLE
GENERATORS
Maybe you want to make sure the food in your
freezer stays frozen if there’s a power outage.
Or you need to power the well pump that provides you with drinking water. Or you want to
be able to use your gas or oil furnace when the
power’s out. Or your at-home business requires
that you have power to run computers or other
equipment.
Whatever the reason, whenever there is
an extended power outage, there is also the
urge by many customers to fire-up the portable
generator to get electricity flowing to certain
appliances. But, if not used properly, that portable generator can pose a severe hazard to line
workers and your neighbors. In addition, the
generator itself also can be damaged if it’s not
connected properly.
Portable Generator
General Information
Here are some common questions, and
answers, about portable generators and using
them safely:
How to select a portable generator
The first step in purchasing a portable generator is to identify the things you absolutely
cannot live without during a power outage.
Usually high on the list will be the refrigerator
and the freezer, a well pump, the furnace fan if
you have natural gas or oil heat, or maybe some
lighting. Consider your list carefully, because
the bigger the portable generator, the more expensive it will be.
Once you have your list, calculate how much
electricity those items need. Look at the wattage of each item on the equipment nameplate
or in the owner’s manual, and add it all up.
Then keep in mind that your generator should
not be run continuously at more than 80 percent of its rated capacity and take into account
that appliances that operate with a motor (like
the refrigerator and freezer) can require two to
ten times their listed wattage in order to start.
Once you factor in those conditions, you
can determine the size of the portable generator you’ll need.
Here is the wattage of a few common items,
just as a guide:
• furnace fan
500 to 2,350 starting watts, depending on
its size
• refrigerator or freezer
About 2,200 starting watts
• well pump
1,400 to 2,100 starting watts
• Sump pump
1,300 to 2,150 starting watts
• garage door opener
1,100 to 1,400 starting watts
• Electric fry pan
1,300 watts
• Coffee maker
1,750 watts
• microwave oven
625 to 1,000 watts
Snohomish County PUD • Electric Service Handbook • Portable Generators • Rev. January 2007
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What can happen if the generator is not used
properly?
The most common problem is something
called back feed. This occurs when a generator
is connected to the home’s wiring system.
The problem typically occurs during a power outage when a homeowner with a forced-air
natural gas or oil-fired furnace tries to operate
the furnace fan by plugging the generator into
an electrical outlet and feeding power into the
home’s electric system. That’s when back feed
happens.
The electricity from the generator will flow
through the home’s wiring, out of the house
through the electric meter, the voltage will get
increased to about 7,200 volts as the current
passes through the transformer outside (yes, it
works in reverse), and then it will flow into the
PUD’s electric system — posing a potentially
fatal shock hazard to anyone working on the
power line or coming in contact with a line that
might be sagging or on the ground.
Can back feed also damage the generator?
Yes, it can. When our utility workers work
on a power line, they routinely use a grounding system to protect themselves. If a portable
generator is back feeding to that ground, the
generator could be severely damaged.
Also, when the PUD restores power to a
home that has a portable generator connected
to the wiring, the sudden flow of utility power
into the portable generator could burn out the
machine.
— How can I prevent back feed?
There are two ways: 1) plugging directly into
the generator and 2) a installing a transfer
switch. The easiest solution is to simply plug
items you want powered by the generator (for
example, your freezer) directly into the generator. But, that doesn’t solve the problem of getting electricity to something that is hard-wired
into the house, like the furnace fan.
If powering the furnace fan is your objective, you’ll need to use a transfer switch, which
disconnects the home’s wiring system from the
PUD’s wiring system and also allows the homeowner to direct the flow of electricity from the
generator to any circuit in the house, such as
the one powering the furnace fan.
A transfer switch should only be installed
by a licensed electrician and requires an electrical permit and an electrical inspection. Most
electricians or dealers that sell portable generators can arrange to get one installed in your
home.
Will throwing the main breaker create the
same result as a transfer switch?
Not safely. Simple circuit breakers do not
make a positive disconnection between the
home electric system and the PUD system.
What’s more, they’ve been known to fail. And,
the consequences are pretty high if it does fail.
The only safe way to create a positive disconnection between the two electric systems is
through the use of a transfer switch.
Snohomish County PUD • Electric Service Handbook • Portable Generators • Rev. January 2007
Are there other safety tips to keep in mind?
Yes. Make sure extension cords are adequately
sized to handle the electricity. If you’re not
certain, ask the dealer who sold you your generator or check with an electrician. Also, the
generator itself should always be placed outside
in a well-ventilated area and you should never
refuel it when the engine is hot. Let it cool for
at least 10 minutes to minimize the danger of
fire.
Instructions on how to properly use a portable generator are included in most operating
manuals. You should read them carefully.
• Damage to the house wiring, appliances,
heavy-duty flexible cord, and/or multiple
outlet strip may result from exceeding their
rate capacity. Damage to the generator may
also result from exceeding the rating of the
generator. This capacity is usually given on
the generator nameplate in watts.
temporary portable generator systems
If the generator is not connected as shown in
Figures 2-1 and 2-2 (which are both considered
permanent connections), the arrangement
shown in Figure 2-3 (a temporary connection)
is an acceptable alternative.
Portable Generator Connections
There are two types of portable generation
connections: permanent and temporary.
permanent portable generator systems
• The methods shown in Figures 2-1 and 22, with switches that disconnect the loads
from the line side before those same loads
are connected to the generator are acceptable methods of installing a standby/emergency generator.
• Installation of the Generator Connection
Cabinet shown in Figures 2-1 and 2-2 must
be approved by the appropriate governmental agency and Snohomish County PUD.
• All nonessential lighting and appliance circuits should be turned off before connecting a generator.
Snohomish County PUD • Electric Service Handbook • Portable Generators • Rev. January 2007
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FIGURE 2-1
PUD
Service
NEC Approved
Conductors
Meter
Generator
Line off
Main Breaker
MAIN
PANEL
Transfer Switch/
Generator Connection
Cabinet
(to be located on the
exterior of the building
adjacent to the service
entrance near the
meter location)
GENERATOR
Transfer Switch
Circuits available from generator
during a power outage
FIGURE 2-2
PUD
Service
NEC Approved
conductors
Meter
Main Breaker
MAIN
PANEL
Utility
Main
N.C.
N.O.
Generator
Main
NOTE
Transfer Switch/
Generator Connection
Cabinet
(to be located on the
exterior of the building
adjacent to the service
entrance near the
meter location)
GENERATOR
Circuits available from Generator
during a power outage
NOTE: This breaker shall be the same size as the Utility/Generator mains.
— Snohomish County PUD • Electric Service Handbook • Portable Generators • Rev. January 2007
FIGURE 2-3
Refrigerator, freezer, etc.
House or
Building Wall
Lamp(s)
Door,
window, etc.
Heavy-duty
flexible cord
Multiple
outlet strip
Other essential
loads or small
appliances
PORTABLE
GENERATOR
DO NOT EXCEED
RATED CAPACITY
CAUTION
Damage to house wiring, appliances, heavy-duty flexible cord, and/or multiple outlet strip may
result from exceeding their rated capacity. Damage to the generator may also result from
exceeding the rating of the generator. This capacity is usually given on the generator nameplate
in watts.
Do not plug generator cord into any existing building outlets.
Snohomish County PUD • Electric Service Handbook • Portable Generators • Rev. January 2007
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PO Box 1107
Everett WA 98206-1107
425-783-8272
www.snopud.com
Form 2242
Rev. 01/07
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