Generator Transfer Switch (Part 2)

GETTING STARTED - Let's figure a few things out first

Assumptions

1) You understand what the following words mean: Voltage, Current (AC and DC) & Power.

2) You know the items you want to power and the power requirements for each.

YOUR GENERATOR:

I own a Honda EM6500.  (Review to come some day)  

I'll walk through all this giving you the data for my generator.

Voltage - measured in volts.  Determine what voltage your generator is capable of producing.  Mine can provide limited 12 volt DC, 120 volt AC and 240 volt AC power.  

Current - measured in amps.  At 12 volts, I believe it can provide 8amps of current.  At 120 volts... I don't know.  At 240 volts AC, it can provide nearly 30 amps of power.  (I only care about the 240 volts)

Duty - ah, mine is rated for 6500 watts!  So I can run it at 6500 watts 24/7 right?  NO!  While it is rated at 6500 watts, what the marketing people didn't mention is that it is only rated at that amount of power for 30 minutes.  If you are going to leave it running longer than that, it is only rated for 5500 watts.

Surge - How long can it handle a power requirement greater than it's typical power draw?  Slightly different than duty, and still quite similar...  My generator can handle a load of 7000 watts for ten seconds.  This is helpful when you have electric motors starting up.  For more information, read up on current in-rush.

 

Digging into this a little bit deeper...

 

VOLTAGE: 120 Volts or 240 Volts? 

It really comes down to what you need to power.  (NOTE: 220V and 240V are interchangeable.  The difference simply allows for voltage drop through a conductor.)  At my house, there is a 240 volt well pump I need to operate in order to do things like take a shower.  Other items that run on 240V will include you Range/Oven, the clothes dryer and possibly a welder or other machine tools.  (I feel like I missed one... if you can think of anything, please chime in!)

HOW MUCH POWER? (Voltage x Current)

I honestly have no idea how much power I will need.  Some people would say I should go get a Kill A Watt electric usage monitor, but I didn't.  I do know my furnace won't start on a 2000 watt generator (also known as 2kW or 2K).  I learned this the frustrating way - I bought a generator and then found out it didn't have the ability to handle the startup current (see below) for the blower motor.  Whatever you plan on doing, you need to make sure your generator can handle the start-up current in addition to whatever else you may have running at that time.  I can speak more on the subject later if there is interest.

A quick note on Start-up Current:

When an electric motor like a compressor for your refrigerator or a fan motor in your furnace kicks on, it uses a lot more current than it does after is up and running.  Or simply put, it takes more power to get it started than it does to keep it running.  For those of you who are of the scientific background, you understand that the static friction is higher than the dynamic - it takes more work to get something rolling than to keep it rolling.

Back to Power and Voltage...

So this time I went with a 6500 watt generator that has the ability to handle surge up to 7,000 watts (7 kilowatts)  It also has the ability to put out either 120volts AC or 240 volts AC.  

Voltage drop - My attempt to explain for those of you who didn't read the Wikipedia article:  When you have power going through a wire, a long one... because of the friction in the wire (also called resistance) you loose some of that power in the form of voltage.  If you plan on running power to something a long way from the generator, you will have a voltage drop!

 

Wire sizing:  (Don't disregard this one, you can burn your house down!)

So again, power is voltage times current.  For my generator, at 240 volts it is producing 30 amps of current.  Therefore, when picking out the components for your generator hook up, you need to ensure they are all rated for at least that much current!  Doing otherwise can cause the wire to overheat and catch on fire... along with you house, you family, possibly yourself and all things you love!  DOOOOOM TO ALL WHO FAIL TO APPLY THIS!

OTHER RESOURCES:

An Overview on Electrical Wire and Cable

The Generator Transfer Switch (Part 1)

If you like electricity, this is worth reading

How many times have you been at home and all the sudden the lights turn off?  It might be snow, ice, a car wreck down the road... Or you could be like my parents; when a hurricane hit Louisiana (the year after Katrina) and all the power line workers went south to help and nobody counted on 60mph winds rolling through the Ohio valley later that week.  This event left my parents out of power for nearly two weeks as there weren't any workers around to fix the lines.  It might be worth noting that all the food in their freezer went bad, including all the recently harvested produce from the garden!

If this (power outage) hasn't happened to you, it likely will a some point in the future.  This and the following posts will hopefully explain to you the course I believe is the best recourse for this emergency event.  

All of this has been done with the following priorities in mind:

Legal- I don't want anybody going to jail.  It is expensive, time consuming and it would make me sad to be apart from my wife or family.

Safety- This is important because dealing with electricity like this can kill myself or somebody else.  (If it meet's code, it should be safe and legal.)

Simple- I am an engineer.  There will be times when I have to go away from home for a business trip.  I want to ensure that my wife, or children (when the day comes they are responsible enough) are capable of doing this while I am away, without any doubt it is done safely and in a legal manner.

 

What is it?

A generator transfer switch is a device that ensures the power from your generator does not leave the house through the power lines coming into your house (through the meter) and kill, for example, the lineman two miles away trying to repair the down wires that caused your power to go out.  It is effectively a two way switch, where only one option can be turned on at a time.  It allows you to simply chose if you want power from the outside power lines or from your generator.  Naturally, if the power is out... you want power from your generator!

 

Other options:

Extension cords: You can run extension cords to all of your (110 to 120 volt) appliances while the generator is running.  This is a very economical option, still legal, and relatively safe.  I won't look down on anybody who chooses to go this method.  (Unfortunately, I don't believe this is a good option when I am required to power things like my 240 volt well pump.)

Back-feed a breaker: THIS IS ILLEGAL, THIS IS NOT SAFE.  I won't even speak of it.  If you want more information on this, check out Steven Harris's page here.

You can read more about Generator Transfer Switches on Wikipedia here.

Why this is no ordinary rabbit! ...run away, run away!

Time to retreat, regroup, and plan the next assault...

Ever see Monty Python and the Holy Grail?  Well my wife, the rabbit, just gave me some constructive feedback : )  She's great for that and I love her for it!

Okay, so  I had to agree with her that what I put out was not the best I am capable of.  With only limited time to work on this I rushed to get it out.  With that said, I have pulled my first two posts on the generator transfer switch back and I'm going to re-organize it before putting it back up.  Hopefully the second time it will be easier to understand, more organized and provide in general a higher quality of material than the first go-round.  Look for something next week.

Generator Transfer Switch (getting there)

I'm on it!

Okay you guys, I just want you to know that I'm working on this one.  I can only post stuff during lunch, and when I'm at home I'm taking my spare time to get the installation finished and take pictures.

Keep your stick on the ice... you should see progress soon!

(Edit- this was supposed to go up yesterday... hmm.  Hang in there, I'll get this blog thing figured out!)

"Rome wasn't built in one day!" An introduction.

Six  years after graduating from college with a BS degree in "I don't know what I want to do when I grow up", I finally landed in a house in the country, with a job in the country, where I can support my family.  For six long years we lived in apartment after apartment, and now I have the opportunity to do all the things I ever wanted to do...

Unfortunately there are a few things in the way... or maybe it's the other way around?  I have a wife and kids, a full time job, etc...

So this is my attempt to re-build my own little Roman Empire overnight!  I want to get it all done now... but I have limited time and resources, and so I must strike a balance...

I must balance the empire