Man Uses Prius to Power House for 3 Days During winter storms

True, but:
1) We're tight for space, & in that case, the tight space gets tighter having to store fuel for the generator.
2) Fuel gets old, turns to varnish
3) 3,500.00
4) Fuel storage .... BOOM!

On the other hand, the prius fuel, continually gets rotated, it's fuel is stored better/safer, and pulling power off it is a lot less expensive, as the PriUPS web site shows.

 

That only proves that Darwin was right

 

The best thing to do is to drain the generator carb float bowl. I do that on all my smaller equipment - lawnmowers, snowblowers, etc - and I even drain the gas tanks, before storage. Next season, add gas, one pull, vroom

To be "legal" and - of course - safe, some sort of automatic transfer switch is needed. By the time you factor in the cost of various inverters, transfer switches, most likely professional installation, you're around that figure anyway

One thing I do NOT LIKE to see, are well meaning but clueless homeowners who intentionally "backfeed" the generator into their breaker box. Eg, they'll use a 240 v electric dryer receptacle, unplug the dryer, plug in the generator

If they forget to turn off the main breaker in the breaker box, they not only backfeed into the utility grid, they also run the risk of spectacular special effects from the generator once utility is restored

For the safety of the homeowner, and the utility crew, you MUST use a transfer switch that isolates the house from the utility.

Improper battery wiring: kaboom. There are many failure modes for providing backup power to a home. For pure thrills, a backup generator running in an enclosed porch, an attached garage, etc, is hard to beat

 

This is not an issue:

• catalytic converter - all but eliminates carbon monoxide
• low duty cycle - 0.25 gal/hr. at maximum load, 1 kW
• 5 gal. / 3 days - 0.07-0.10 gal/hr. in reported use

This is no worse than running a kerosene heater and one of the advantages of a Super Ultra Low Emissions Vehicle (SULEV.) Unlike the traditional gasoline powered generator, the Prius has a sophisticated catalytic converter that is lacking from an ordinary gas generator.

You are right to be afraid of a gas generator in a garage. But the Prius in contrast, would be all but risk free and in this particular use, quite safe.

Bob Wilson

 

That's good to know. I thought that the catalytic converter only removed the nitrous oxide; I didn't know it also removed CO.

However, in an over-abundance of caution, I think I'll continue to route my exhaust out of the garage. Better safe than sorry, especially if my ICE is running more frequently, due to my drawing larger amounts of power from the HV. No carbon monoxide is better than ultra low levels of the stuff.

 

We have a carbon monoxide detector in our home but it is line powered. I do not know if it works with a modified sine wave or other, non-sine wave power source. ... Something else to test.

Bob Wilson

 

MrK(2), I'm building a HV backup system for my Prius and am just about at the point where a hose came to mind: what hose did you end up using?

BTW, I got home from a late night flight once and decided to listen to the Prius stereo for just a few minutes...fell asleep. Woke up about 4:00am still alive, stereo still playing. I still think I'll use a hose.

 

With my original system, a 12Vdc inverter, I simply slid a hose from my ShopVac over the exhaust pipe and under the garage door. The exhaust pipe got fairly warm to the touch, but not hot.

With my HV system, I anticipate more frequent cycling of the ICE, and as a result, a hotter exhaust pipe. I intend to buy a length of flexible exhaust pipe from the local auto parts store and a hose clamp to attach it to the exhaust pipe. I should be able to tighten it enought to assuage any concern about exhaust leaks.

 

I think that backfeeding the grid is overrated as a danger. In the first place, it won't work, since there are far too many loads on the grid than any small generator could support. So the self protection devices on the generator will kick out, or the generator will self destruct. Linemen who repair the grid don't depend on the grid isolation equipment working. They ground the lines that they're working on, or isolate themselves from ground. They clearly prefer all the protection techniques that could be applied, but I do think their procedures make them safe even in the presence of a generator backfeed.

There was a case a few months back where they were working on some high tension lines that were supposed to be turned off. Somehow power was applied while they were working on the lines, and it caused a several hour blackout to a large area of San Francisco. The workers were unharmed, and the protective ground that they applied took out more than just circuit breakers. No doubt there were a few angry words from the linemen, but they were safe.

 

I'd be inclined to agree with you RobH.

Still, if my neighbor and I both have backup generators and I have a transfer switch installed, and something terrible goes wrong, we know who's not going to be a suspect.

I guess I'm paranoid but I'm going to install one, they're pretty easy to hookup once the principle is understood.

 

Correct, in the majority of cases the protective equipment will work as advertised. I didn't want to get into that, as the layperson won't be able to follow the discussion

But you left out something. What about the automatic reclose that is standard on most MV and LV distribution systems?

For some reason, they vary widely in reclose interval. Some will attempt to reclose - to send a test charge - after only half a minute to a minute. Others may have a 5-10 minute timeout before attempting to reclose

Say a tree falls on a power line during a torrential downpour. It doesn't break the line, but still shorts out the 7,200 v primary. The automatic reclose may wait up to 10 mins

Say in that time, the homeowner gets his generator running and plugged in. He forgets to turn off the main breaker. About that time, the recloser snaps on

Fireworks

So in all cases, a picky transfer switch, even a dinky manual one, is the best way to go

 

I didn't know about automatic reclose equipment. I thought it took a human closing the appropriate switches or circuit breakers to restore power. Just learned something.

But if you connect an ordinary size generator to the grid, it will just kick out immediately. About the only case where it wouldn't is if all your neighbors on your local circuit have everything turned off. Independent of safety, the reason you don't connect your generator to the grid is that it doesn't work. In fact you probably can't even successfully connect a generator to your whole house circuit because it isn't big enough.

My 50+ year old house uses a 100 amp main circuit breaker. 100 amps times 240 volts equals 24,000 maximum watts. Unless a backup power system can support the maximum distribution panel wattage, then you'll need to make some decisions about what needs to be backed up, and what will be left off.

A properly designed house backup system uses a separate circuit panel that feeds circuits that can be supported by the available backup power. These circuits include basic lighting and favored appliances. They generally do not include heavy electrical loads such as electric water heaters, ovens, and stoves.

So the transfer switch should really just handle the critical circuits panel. It's a significant part of the initial design of a house, or an even bigger project to retrofit an existing installation. Certainly a lot larger than pulling the main breaker and plugging in a 2000 watt generator into the nearest outlet.

It may be a kludge, but it's probably better to run extension cords from the backup power to the specific electrical devices that you want to run. If the power isn't a clean sine wave generator, then you certainly don't want to attach all your electronic equipment and motors. If you insist on feeding the standard home wiring, then the first project before enabling power would be to run around disconnecting all the electronic gadgets and confirming that appliances are turned off. Burning up the central heater air distribution motor is not exactly what you want to do in the middle of a storm caused blackout...


I had an interesting conversation with the electric company inspector who came out to check my solar panel system. His biggest concern was the inverter (generator) disconnect switch next to the electric meter. While there are strict rules about that switch, he seemed to regard it as so much electrical code bling. He commented that he would never trust such a switch. If he needed to isolate a house from the power grid, he would just unplug the electric meter. Or cut the wires up on the pole. He certainly didn't trust disconnect switches, or even pulling the main breaker at the service entrance. About the only value he saw in the disconnect switch was the sticker he put on it warning that there was a local generating capacity.

 

If you're curious, Cooper makes a line of air and oil reclose equipment. They are very reliable even in our cold climate

Reclosers and Controls

On the subject of electrical safety, the widespread use of reclosers should be an obvious safety concern to you. Say you happen to witness, or come across, a car crash involving a utility pole.

When the crash first happens, the pole snaps at the base, and wires at 7,200 v or higher, lay draped across the car. Sparks are zapping, then suddenly they stop. A "hero" will assume the danger is past, and rush to the aid of the driver

As this well meaning bystander starts to drag the limp body of the driver out of the car, the recloser times out. The well meaning bystander becomes another statistic. Yes, this event has happened before, and no doubt will continue to happen in the future

Never, EVER attempt to assist anybody in that situation.

EVER

Call the appropriate experts. They have had training to work with MV and HV events, you have not. For example, every recloser has a manual operating handle. Linemen with appropriate equipment - eg a "hotstick" - can manually lock out the recloser, ensuring their safety

No, not always. There have been enough incidents to prove this belief wrong. If it wasn't a concern, utility companies wouldn't warn about it

CMP | Avoid Deadly Backfeed

Seattle City Light | Generator Safety

Generator Guidelines : Lafayette Utilities System

This clearing house of generators offers the following

Safety

Most homes have standard 100 amp or 200 amp service. The vast majority of homes use a small fraction of this ampacity. For example, my home has natural gas heat and a 200 amp service. It has way more ampacity than I'll ever need

Even with the central A/C and electric dryer running at once, I peak at around 40 amps. Since my monthly power consumption ranges from 480 kwh to 900 kwh (Lowest in fall and spring, highest in July), it's pretty easy to do the math and figure out my average daily and hourly power consumption

Another thing to keep in mind is that the main breaker is usually required by local code, to have higher fault interrupting current rating, than individual branch breakers. In the US, the branch and main should have equal fault rating, depending on jurisdiction

For example, the Federal Pioneer StabLok breaker box in my homes has a main breaker rated 22 kAIC. Both are 200 amp breakers, but the fault rating is 22,000 amps. The branch breakers are 10 kAIC

Unless you have electric heat, a typical backup generator should be fine unless attempting to run an electric dryer, or a +2 ton central A/C

Yes, I'm pretty sure I covered this about generator panels that have a manual reselect switch.

Remember that it is also illegal - and dangerous - to rig up your own transfer switch that has a "floating" neutral. In the case of manual reselection, you *must* switch the neutral as well. The reason? As a hint - the neutral is usually bonded

Most basic generators will be fine with inductive motor loads. The noise introduced by most generators may cause issues with sensitive electronic loads.

These issues are no worse than a utility that has a large industrial plant on the same grid as a residential area. There will be odd-order harmonics introduced by capacitive and inductive loads at the industrial plant.

It's a constant PITA for a utility to ensure PF compliance from their commercial customers. This technical article from Eaton describes the benefits of using a capacitor bank to achieve better PF compliance

http://www.frontierenergysystems.com/resources/harmonics_and_caps.pdf

I'm familiar with this line of PF products

Square D Power Factor Correction Products- Low Voltage

I would really like to meet this "expert." What he told you was flat out wrong, old wives tales, and dangerously so.

I would really like his opinion - and I bet he has one too - on reclosers and capacitor banks