Wiring a Generator to Your House
blog.wattvision.com
blog.wattvision.com
If you try to wire your generator to your breaker box as a DIY project, you probably will not be in compliance with local electrical codes. Also know that it's extremely dangerous. For example, if your ground wiring is not done properly, you may inadvertently put 200+ volts on 120 volt lines, immediately frying bulbs and electronics connected to those lines, and potentially starting fires. Don't do it.
Someone picks it up and ZAAAAP.
I agree, don't do it.
http://cd.textfiles.com/group42/ANARCHY/COOKBOOK/BLOTBOX.HTM
As well as the extreme importance of having a 'generator interlock' - something that physically disconnects your house from the power grid, so you aren't electrifying external power lines (lines that people expect to not be electrified when the power is turned off).
Seriously, speaking as someone who has worked as an electrician. Unless you're experienced, don't play with it.
Easiest permanent DIY job would be to wire a dedicated outlet to your fridges and freezers and any important electrical equipment, and switch them to the generator outlet when you need it. No crossing circuits, no real problems.
If you have no electrical experience, deal with the extension cords.
If that happened you would know because your lights were on.
And what would actually happen is nothing, because the generator circuit breaker would blow from trying to power the entire neighborhood.
The only way this could happen is if you were right at the end of the feeder line, and managed to down a line such that only you and your neighbor were online - in which case enjoy the free power. (And then yell at your neighbor to fix it.)
Do things properly, sure, but don't over estimate the danger.
For a normal installation - definitely, do it properly. But in an emergency? Just turn off your main breaker.
(at least every year there is a hurricane).
It is probably less of an issue up north since people are probably leaving their windows open rather than having them shut and the AC on, but it is worth repeating.
Wouldn't they be wanting to heat their houses, instead?
Two clarifications on the article: 1. A L15-30 is a three phase delta twistlock connector. The author means the L14-30.
2. "For example, if your ground wiring is not done properly, you may inadvertently put 200+ volts on 120 volt lines, immediately frying bulbs and electronics connected to those lines, and potentially starting fires." - What the author means to refer to here is accident lifting of the neutral connection. See this excellent thread (complete with demonstration video) on the professional sound forum:
http://soundforums.net/lighting-electrical/4812-why-open-neu...
If you're interested in a general understanding of generators and grounding, you can read a post of mine, also on the professional audio forum:
http://soundforums.net/lighting-electrical/5216-running-gene...
If you've got any specific questions on the topic of generators, I'm happy to give them a go.
Grounding is not isolated, but NEC-compliant star grounded (See NEC 400.8, 520, 525, 530 (movies), and 640 (carnivals) )
Loop area is actively minimized
Signal transmission is via instrumentation amplifier topology (i.e. differential)
Shielding is designed to minimize shield current induced noise (SCIN)
These Rane tech notes gives a good overview on some of the topics above: http://www.rane.com/note165.html http://www.rane.com/note166.html
The AES standard for audio interconnects is here: http://www.aes.org/publications/standards/search.cfm?docID=4...
Note that disel and plain old gasoline generators push out really noisy power. Do not hook up electronics to gas generators without a line conditioner or UPS in the middle (and the UPS will probably complain about voltage sags and/or lack of grounding).
If you're going to make it a permanent fixture to your home that you can actually rely upon, you really ought to make it run on natural gas and/or propane (as a failover). Quieter, cheaper, and less likely to be a shortage (most homes without power in NY/NJ still have natural gas and a modestly sized propane tank could run our generator for a whole week at full load, and we had contracts with multiple firms to bring propane).
Also, make sure you test and condition the generator periodically, as any oil-lubricated engine left idle will eventually freeze up.
Finally, you want to oversize the generator just a touch, as running them at 100% is a great way to burn it out relatively quickly. If you can keep it at about 80%, it'll increase the longevity of the unit, and also give you some fudge factor.
Why no exceptions? This isn't really that hard to do, as long as your have some knowledge, and you researched in advance what to do.
Obviously if you are unsure of your skill and/or knowledge level don't do it. But you don't have to be licensed to know what to do.
Given how cheap it was for the actual labor, I'm not comfortable taking that risk. YMMV.
This is way down on the list. Hire someone if you want, but don't tell people "no exceptions" there are plenty of quite handy people who would have no trouble doing this properly.
Like you said: It's not really that hard.
There have been plenty of discussions on HN about this phenomenon, but I can't remember what it's called.
-Also I advice do not plug in in an outlet via male to male. Reason: if your peak is over 5kw/h, the wiring might not handle that! See the 48kw/h wiring of yours is the calculation of the total amount each breaker can have. I don't know US breakers but lets say it is 120v/40A per breaker, you have 10 breakers. But if you connect your generator on the outlet on one breaker the electricity has to travel through one specific pair of wires all the time (from outlet to wire intersection spread from there)
You'd just end up limiting your max power to the capacity of that one circuit, and overloading would trip the breaker on the circuit you were using to backfeed. Technically if you were putting 20A into a 15A receptacle on a 20A circuit you'd be overloading it, but the same thing can happen when drawing power and such circuits are still condoned. Also technically you should only consider that circuit sufficient if you aren't planning on having a continuous load greater than 12/16A, but people generally don't pay attention to that rating either.
(Although the generators I've seen where one would be temped to use a male to male 5-15 plug have a 20A breaker on those receptacles)
Usually you can do your own work and then get a licensed/bonded electrician to sign off on it, even in the US.
I can't do work for hire (due to licensing...), but pretty much anything short of medium voltage I'd feel comfortable DIY. It is not rocket science. There are some tricks in actually running cable in older buildings, and how stuff is wired most commonly, which are worth learning hands-on, but everything else is fairly simple theory and can be learned from reading.
The author is right in saying that they don't need a 23kW generator. They probably also don't need a 5kW generator. If they actually investigated the cause of the various power peaks, I bet they could disable or replace that usage with something else. A graph is nice, but a few labels ("this is where we turn the kettle on", "this is when we get home from work") would provide so much more information.
Just a little power management could probably cut peak power down to a couple of kW, and slightly more effort could get it lower still. Beyond heating (which is woefully inefficient if electrical), there's very little that a person (or family) need at any one time that draws above a kW.
Granted you can survive without these devices, but it may be thoroughly unpleasant, result in an awful lot of spoilt food, and if a power outage is longer term, having to significantly adjust your eating habits.
That's easy. My (old) fridge/freezer used about 80 watts when averaged over time (peak is 300W when self-defrosting). There are Energy Star refrigerators that use only 34 watts averaged.[1]
>air conditioning units
This is certainly true for now. Over the long term, low power passive cooling can be surprisingly effective. Taking advantage of evaporation, diurnal temperature changes, "wind chill", thermal mass, phase changes, passive geothermal, and solar gain reduction have the potential to provide comparable comfort for a lot less energy.
A small personal anecdote: in college I had no AC, so I would circulate night air through my apartment ($15 fan + $5 timer). It reliably kept it 5-10 degrees cooler than it was outside, but doing nothing it was 5 degrees hotter. It cost $6/month, drawing 60 watts on average, even with a very inefficient motor.
[1] http://www.energystar.gov/index.cfm?startNum=1&resultspe...
Oh, and the microwave.
I've worked and lived under emergency conditions with no power, running off a generator, and the clothes dryer, range and dishwasher were the last things we cared about. Light, telecommunications (we had long-distance antennas) and phone charging were the most critical needs.
I've also spent time in 100%-self-powered villages, and with good solar and wind power you can indeed have your dish-washers etc, just not in an emergency when you need to conserve and share energy (people running around sharing newly-charged battery packs was a common sight).
Generating electricity isn't really an issue if you have a good solar/wind pack: it's battery. I've often found running a converter from a car has been more efficient than relying on someone's home-built battery pack.
I'm just saying trying to live normally on a peak power of a couple kW might be optimistic. The dryer alone draws two or three.
I suppose if you decide that you must live a "normal" life, then you can't really change anything about it. If you decide that you want to live a comfortable but low impact life, then there's plenty of things you can do to reduce your peak power.
I do have some clothes that I dry on a rack, and they always come out very stiff compared to the stuff that goes through the dryer. I feel like I should hit those sweaters with a rugbeater or something before I wear them.
The Pacific Northwest had a similar (but smaller) storm to this in 2006. We had much less sea damage, but more wind damage from trees falling over. Power out for 10+days for some people.
14 people dead in WA state, but 8 of these came from CO poisoning - 5 in 1 family because they ran the generator in their garage!
http://en.wikipedia.org/wiki/Hanukkah_Eve_wind_storm_of_2006
My in-laws used a generator for this time. They were out for 10 days, and needed to walk 2 miles each way (due to downed trees) to get gas for the darn thing. No-one thinks about the gasoline infrastructure needed to keep vehicles and generators going if the power is out for multiple days. New Jersey is finding this out right now!
So when the wiring was under modification for a kitchen remodel, we had the electrician install a transfer switch on which we put our 10 most 'useful' circuits. Then when the power went out we could fire up the generator outside, plug it into the transfer switch and transfer power from the AC 'mains' to the generator.
That works fine but you have to be careful because the power generated by Home Depot generator is pretty crappy power. The computer systems were protected by using a UPS system that used AC primary power for battery charging and ran the load off an inverter. At some point I'll find a datacenter throwing out an old AC line conditioner and I'll get that.
(Yes I could get one welded on. I have a need for additional generators, and for some reason noise level seems to be a state secret with those things.)
In both the live concert and movie production worlds the Eu6500 is a frequent fixture on site as the small generator of choice. I also have good experience with the smaller EU3000. The line can be found here: http://powerequipment.honda.com/generators/inverter-generato...
Yamaha also makes a line of low noise inverter gensets. They also have a 4500 watt class model. A friend of mine choose one of the Yamahas over the Honda: http://www.yamaha-motor.com/outdoor/products/modeloverview/c...
Please note that both the Honda and Yamaha lines are much more expensive, and put out much cleaner power, than the typical construction generators prominently featured for cheap at the big box retailer. Buy once, cry once.
Since you indicate you are considering multiple generators, you could move up the food chain to one larger enclosure-mounted installed generator. There are many choices, but my personal recommendation are the ones from Onan, who dominate the recreational vehicle (RV) generator market: http://cumminsonan.com/residential/
For perspective, a common "small" portable generator for technical show power is the Multiquip (MQ) DCA45. It is a 45KVA-class generator with equivalently sized diesel prime mover: http://www.multiquip.com/multiquip/DCA45SSKU.htm
The smaller Honda 3000 (wheels are good) seems about right. 57 dB (A) is 1. advertised (hooray!) and 2. very acceptable. Ordering such beasts from the web gives me a case of the willies, hopefully I can find distribution nearby.
Thanks again for your answer.
The Honda generators are as nice as the price would indicate :) In general be wary of generators that give sound levels with out a distance and weighting curve specification.
1. The starting current of a motor, which is higher due to multiple factors (e.g. no back emf, "starter winding" current, charging motor starter capacitors, etc.).
2. The concept of power factor, which represents the fraction of in-phase current traveling in the circuit (i.e. the current actually performing mechanical work)
Generators give output ratings in KVA to reflect the total amount of power that they can source from their prime mover without no consideration of power factor. Most larger generators also give a "real" power rating in watts that de-rate for the power factor. See this small commercial genset as an example: http://www.multiquip.com/multiquip/DCA45SSKU.htm
Only the current and voltage that are in phase perform work on the device under power. If the power factor is 1 (i.e. completely in phase) then the KVA and KW ratings would be the same. This, as you say, is the case for purely resistive loads.
For loads with a reactive component, there is a current fraction that remains in quadrature is bounced back and forth between the source and the load. Since real world conductors and generator windings also have ohmic resistance, the quadrature current fraction is partially dissipated as heat, and lost outright.
Many municipalities mandate a certain power factor for the industrial customers. Typically 0.9 or greater. This is to minimize the ohmic losses in transmission lines from the reflected quadrature current. Industrial facilities are typically inductive in nature, because of the large number motors. So, at the outlet of the facility they will install some shunt capacitance to offset the phase angle of the motors inductive character and bring the current back in phase.
The worst-case power factor I've ever personally seen was on cruise ships. Since those things are essentially one giant mechanical plant (motors galore), and have multi-megawatt electric propulsion they have a power factor of 0.7, or even slightly less!
What's the problem?
Their main concern is clearly to plug their product, not to provide useful advice on installing a generator, and the fact that they are exploiting a natural disaster to do so is pretty low.
You also need to account for multiple motors turning on simultaneously which you may not catch with a simple measurement. You need to understand what the demands for power are as well.
They are even rated that way 3200/4000 is a typical rating.
Size for the normal load, and let the peak rating handle the startup currents.
The instructions completely didn't say what to do with it. When I looked it up online people are saying you need to have an 8 ft metal rod going into the ground?? Who's going to do that for a portable generator.
What do you guys do for grounding? And if you install a transfer switch does that change the grounding needs?
People that worry about becoming the path of least resistance to ground when they touch the equipment.
I personally wouldn't worry about a grounding rod if I was just running a few extension cords from the generator to power a handful of necessary things. The important thing is for all of the devices to be grounded back to the generator. This means 3 conductor cords for 3 prong devices, 4 conductor cords for 4 prong stove/dryer. 2 conductor non-polarized cords should be fine for modern 2-prong "double insulated" devices. In NO circumstance do you want to be using a 3-prong to 2-prong "cheater" adapters or anything similar.
Once you start talking about transfer switches and wiring it into your house, the picture completely changes. Unless you have experience doing house wiring, are up for dealing with live non-current-protected wires, and are open to learning something new while meticulously checking yourself, you really do want to talk to an electrician
There is much more to it than the article might imply to you.
So for a 3-day supply, you would need $9k in batteries? Not bad...
http://www.nrel.gov/docs/fy02osti/31689.pdf
But yes it looks like you can also manage about half that cost for a similar system (their stated range is $80-$200 per kWh).
A 5KW gasoline generator is $500 new, significantly less used and definitely much more reliable than car batteries. It would also probably out last them. And it requires practically not maintenance whereas most car batteries that aren't in use would die without constant maintenance.