If you are Local to Santa Cruz and need a Standby Generator Installed, or a portable transfer switch - call or email us for a FREE QUOTE:
Service@StallingsElectric.com or 831-335-2407
I want a generator, but I don't know where to begin!
No worries! Consider this a fairly quick and thorough guide to learning about powering your home with a generator. Skip around as you please!
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What exactly is a generator?
Home generators are used as an alternative source of electrical power from your main power service to energize your house/business circuits or individual appliances. These amazing machines convert mechanical energy into electrical energy through the use of an internal combustion engine and manipulation of magnetic fields.
Common generator terms that you’ll want to know:
kW or watt: A kilowatt is 1,000 watts (a unit of power). A kilowatt-hour is 1,000 watts used for one hour. As an example, a 100-watt light bulb operating for ten hours would use one kilowatt-hour (equal to 1000 watts). A helpful formula is Watts = Volts x Amps. Example: if you have 120 volt fridge that runs at 6 amps, it costs about 720 watts to run (720 = 120 x 6).
Transfer Switch: This is what a generator needs to be run through to power an electrical panel safely. It is an electrical switch that switches loads between two sources (i.e. generator vs main utility service). Available as manual (switched by hand) or automatic (detects power outage and switches itself).
Standby (or Fixed): A generator that is not meant to be moved, normally tied into an electrical panel and gas line (natural gas, propane or external gas tank). Most modern standby generators will exercise themselves on a weekly basis to ensure peak performance and better maintenance, they also have the benefit of automatically starting during a power outage. Standby generators are meant to power multiple circuits (many devices) or an entire house/business.
Portable: As the name suggests, these generators are meant to be mobile. They generally have an onboard gas tank (that needs to be frequently refilled) and need to be manually started (either by pull-start or electric ignition via battery power). The smallest portables (1kW-4kW) are meant to have devices plugged in directly to their set of onboard plugs, while larger devices (5kW-12kW) are generally meant to be plugged into a transfer switch to energize home circuits, and most of them also have on-board plugs to power stand-alone devices.
Typical Generator Sizes Based on Home Requirements
Important Note: These generator size estimates are for a typical home setup that relies mostly on gas fueled appliances. If your home uses an electric water heater, electric range/oven, multiple water/well pumps, a larger size is recommended to power those appliances.
7.5kW: For an average sized household, you can run your important appliances/devices with a 7.5kW generator (lights, fridge, freezer, internet, computers, etc.), this could be a standby or portable generator.
10kW: If you want a little more than just the essentials, you’ll probably want to consider a 10kW generator. This will support a small well pump or a larger electrical appliance if used in a conservative manner. This could be a standby or portable model.
14kW+: If you have an average household with about 4 people living there, a 14kW generator will probably power the house without you being able to tell much difference from your normal power. This would be a standby generator that powers an entire panel (or just the primary circuits of your choosing).
20kW+: If you have a large house or want to do power-intensive activities during an outage (like charging an electric car), you’ll probably want to consider a 20kW or larger generator. This would be a standby generator that most likely powers an entire house panel.
Calculating Your Actual Generator Size/Wattage Needs
Here are some common household essentials and their approximate average wattage draws:
Refrigerator: 600 watts
Microwave: 1,500 watts
Dishwasher: 300 watts
Electric stove top/range: 2,000 to 3,000 watts
Furnace (1/4 hp fan): 1,000 watts
Electric Dryer: 6,000 watts
Washing Machine: 1,200 watts
Electric water heater: 4,500 - 16,000 watts
TV: 200-400 watts
Computer: 200 to 800 watts
Lights (Incandescent): 60 to 100 watts per bulb (LED lights are typically less than 5 watts!)
Sump pump: 750 to 1,500 watts
Portable heater: 1,500 watts
Window air conditioner: 1,000 watts
Electric Car Charger Lvl 1: 2,000 to 3,000 watts
Electric Car Charger Lvl 2: 3,000 to 10,000 watts
Here is a great tool for estimating your wattage needs: https://www.northerntool.com/shop/tools/buyers-guides_wattage-calculator
Additionally, here is a chart from Honda that lists approximate Surge and Running wattage for all common devices/appliances: https://powerequipment.honda.com/generators/generator-wattage-estimation-guide
A note about Starting (or “surge”) wattage vs Running wattage:
Starting wattage, also called surge wattage, is the amount of watts a device requires upon startup or peak power. Running wattage is the wattage required from the device/appliance to continue operating after startup. Surge wattage is usually significantly higher than running wattage. For example, a fridge may "surge" to 1,200 watts after the door has been opened and it needs to cool back down, then it will return to it's 200 watt running draw after the temperature has normalized.
Generally speaking, it is safe to calculate your generator size based on starting wattage, but an in-depth analysis is best. Not all appliances will be at startup/surge wattage at the same time, nor will all your appliances be running at the same time. Determine how many appliances will actually reach starting/surge/peak wattage at the same time and then add your other devices at running wattage. Base your number off of that wattage and add an extra 15% to be safe.
You’ll want to choose a generator that outputs a little more than your needs for the following reasons:
It will keep your generator from overheating and shutting off when multiple appliances/devices/tools are at peak/surge power.
Running a generator near its full output potential will put too much stress on the motor and positively reduce its lifespan.
Running near max power output is generally very noisy, just as if you were driving your car at full throttle. It can be a disturbance to you and those around you
Having spare wattage gives you cushion for appliances/devices/tools you didn't consider in your calculation, and the capability to add some more devices without any worry.
Should I get a Standby or Portable Generator?
Most people will consider both types of generators when they are planning to power their house. The decision is usually based on convenience and price. Here is a basic bullet list of pros and cons for each type.
Standby Generator Pros and Cons:
+ Maximum convenience, the generator turns on automatically when the power goes out
+ Doesn’t require anyone on-site to start (prevents risk related to food spoilage, flooding due to lack of sump pump, etc.)
+ Much quieter and more efficient than portable models
+ More powerful, with the ability to power an entire house panel
+ Generally no stress about having to re-fuel, with a non-stop supply of natural gas or propane
+ Very little maintenance required. Generator runs a weekly maintenance routine to remain at optimum performance. Change oil and filters annually.
+ Safer in almost all regards. Permanent connections, installed to code by a professional.
- Not portable. Generator is connected to gas and panel via threaded pipe and conduit.
- No external outlets for on-site individual devices
- Generally more expensive when comparing small sized models
- Requires more upfront effort for planning and install
Portable Generator Pros and Cons:
+ Mobile and can be used at multiple sites
+ Generally less expensive and more varieties in wattage
+ Often have individual 120v plugs for individual appliances or extension cords
+ Can be setup nearly anywhere (but still requires safety clearances)
- More setup and maintenance required in nearly all circumstances. Commonly, a portable generator will need to be rolled into place, plugged into a transfer switch, have the transfer switch flipped off, prime and pull-start the generator (unless battery operated), flip transfer switch back to generator power, then add fuel on a regular basis to keep it running. When this is done during a storm it can become frustrating or even dangerous.
-Must be on-site to start the generator (risk of food going bad when not at home, etc.)
-Almost always louder than standby generators of similar size.
-Fuel efficiency is not as good as natural gas or propane and requires refilling.
-Requires more maintenance for longevity: Gasoline stored for long periods of time will break down via evaporation. Old gas will become “gummy” and enter the generator fuel system and make it much less efficient. Fuel stabilizer chemicals can be added to your generator gasoline to extend its storage life (up to about 2 years). Oil will need to be changed more frequently.
Natural Gas Generators - These are standby generators (6kW to 27kW) that are directly tied into the natural gas lines that are commonly found in suburban or urban houses/businesses. If you have a gas meter on your property or pay a gas bill, you probably have natural gas. Standby natural gas generators are considered the most efficient residential generator type.
Propane Powered Generators - Most commonly these are standby generators (6kW to 27kW) that are run off of large permanent propane tanks (mostly used on rural properties). If you are using your generator for a home or business, the minimum recommended propane tank size is 200 gallons. Propane generators burn about 1.5 to 3 gallons of propane per hour. Some portable gasoline powered generators also support “dual fuel” that provide the option of hooking up to standard portable propane tanks. Keep in mind that code calls for placing your generator at a minimum of 10 ft from any fuel source.
Image from http://rcagenerators.com/
Gasoline Powered Generators - These generators are almost always portable (unless commercial diesel) and output power from 1,000-12,000 watts (1kW to 12kW). They usually have their own self contained gas tank, but can also have an independent tank that fuels them.
How Loud are Generators?
Generator noise is rated on a decibel (dB) scale, which is a logarithmic scale. To put it simply, every 10 points on the decibel scale is about 10x louder. So a 63 dB generator is almost 10x quieter than a 73dB generator. That is a huge difference in sound. Nearly all home generators land somewhere between 63dB to 80dB (which again, are very different levels of noise).
The way I like to compare Standby Generators to most Portable Generators is like a running a hair dryer on low (Standby gen) compared to running a leaf blower at full power (Portable gen). You can easily have a conversation over a hair dryer by raising your voice a little, but it is very difficult to have a conversation over a leaf blower. Most people who install a standby generator outside their home will not hear it running from inside when the windows and doors are shut, but a portable generator in the same place will most likely create an audible humming noise that may bother some people.
Rough Comparison:
10kW Generac Guardian Generator dB level = 61 db from 23ft away (hardly noticeable)
9.4kW Firman Portable Generator dB level = 74 db from 23ft away (very bothersome)
In general, standby generators are much quieter than portable generators, due to their fully enclosed engines that also use sound proofing insulation.
What are Ballpark Costs for a Generator + Install?
Here is a chart with VERY ROUGH estimates for the TOTAL cost of a fully installed generator. This includes EVERYTHING: the generator cost, transfer switch cost, battery cost, and labor cost. Keep in mind, these cost ranges can change depending on unique circumstances and can exceed estimates if gas or electric tie-ins have long runs or complexities.
I’ve Got My Generator Figured Out, What Else Do I Need?
Transfer Switch
Generators are plugged into a "transfer switch" which determines/changes where the circuits will be powered from (main utility service or generator). Smaller watt generators can only power a handful of circuits on a transfer switch, while more powerful watt generators can power your entire house through a transfer switch. You need a transfer switch to safely run a generator (it is the law) - otherwise you put yourself, your appliances, your generator and utility worker’s lives at risk.
Concrete or Solid Pad (Standby Generators):
You’ll want to place your generator on a pad of some sort to keep it off the ground to avoid damage from the elements and keep it level. The generator should be set on a bed of at least 3” from soil. You can pour a concrete pad, or buy a manufactured pad, or even pour pea gravel 3” deep. The most important thing is that the pad keeps the generator level and away from water and dirt.
Fuel Source:
You’ll need a source of fuel to power your generator. For standby generators, you’ll need natural gas or propane. The closer the standby generator is to your main fuel source and electrical panel, the cheaper the installation will be (with a preference of being closer to the fuel source).
Where Should I Put My Generator?
Clearance Requirements:
Here are some standard requirements for most generators:
-10' ft away from any fuel source (natural gas or fuel tank)
-18" from the backside of the generator to your house or structure
-60" inches from any doors, window, vents, or fresh air intakes
-36" open space at the front of the generator and both sides
-5’ of clear space above the generator for airflow
Noise Levels
Most counties have noise requirements in regards to generators. Santa Cruz County has the following code: If the generator is located within 100 feet of a residential dwelling unit, noise attenuation measures shall be included to reduce noise levels to an A-weighted maximum exterior noise level of 60 dB at the property line and a maximum interior noise level of 45 dB within nearby residences. You can check the spec sheets of your generator to see the output dB (decibel) levels and then plan on putting your generator somewhere that your neighbor receives the noise at 45 dB or less when indoors.
If you can't find a proper place to put your generator and meet these noise requirements, you can look into permitted noise reducing enclosures or panels, such as the zombie box: https://www.zombie-box.com/
Final Notes
That should cover most questions and concerns about installing a residential generator! Be sure to check your local code requirements, as each county is different. If you have any additional questions or want to schedule a survey for a free quote, please contact us at: service@stallingselectric.com!
Stallings Electric proudly serves the Santa Cruz area and performs free quotes for any residence in Felton, Scotts Valley, Ben Lomond, Boulder Creek, Brookdale, Santa Cruz, Soquel and Aptos.