I've got a metered main panel which feeds a small subpanel in my pumphouse with 10-3 via a 30 amp breaker in the meter main panel. I also feed a 200 amp house subpanel with 2/0 lugged to the busses in the meter main and the subpanel with a 200 amp main disconnect in the subpanel.
Can I backfeed the 200 amp subpanel from the pumphouse subpanel by switching the main breakers in the meter main panel to off and connecting a generator to the pumphouse panel? It seems like the electrical connection is there and flipping the meter main breaker off would disconnect the meter from the main panel buss.
This is not a question of whether this is NEC permissable, just whether its electrically possible. The purpose of this is to quickly power the pumphouse and also power selected low-load circuits (e.g., 2 amps or less) in the house subpanel with a small generator in the short-term before I properly interconnect a back-up generator with the meter main panel.
NEC is a safety code. Like all codes is sometimes goes too far. In your scenario, however, the potential risk of a lot of very bad things happening far outweighs your desire for a quick fix.
Look to the code and act responsibly for your family's sake and the public in general.
I'm confused on the "meter main panel". Typically when you open the main breaker it disconnects the load side of the meter (not the line side). When you say metered main panel I'm thinking this is a combination panel with a few breakers and a ring base meter in the same panel. The utility connects to the line side of the meterbase.
If this is true you risk backfeeding the utility via and meter. This of course is a potential safety hazard for any fellow lineman, or if power is restored when the generator is on line you risk "launching" your generator thru the pump house. I take it the 10-3 is fed to the pump house is on a 2 pole 30 A breaker, and that your generator is a 240 V type. Depending on distance voltage drop may be a problem.
If you risk backfeeding the utility as describe above then don't do it until you properly interconnect a backup generator with a manual transfer switch (double throw safety switch).
hearing aid died and didn't know generator was still running when main reset,
little kids watching what you do,
bigger kids watching what you do and think this is more fun than the shaving cream trick,
the stoopid pill taken to think safety is not an issue here.
Linemen get juiced when they don't pay attention. They generally pay attention and constantly monitor the line condition and take other protective measures. The bigger problem is that power down generally means lines down - and that exposes nonprofessionals to hot stuff.
The possibility of this homeowner having a bad day in his own home is also great. I have several scenarios in mind that are potential disasters waiting to happen. [Launching his generator from the pump house was one thought - but already taken! (Great Response!)]
How many pros here want to light this up?
I'm a code guy - but practical - where do we draw the line? My genset cannot be started unless the main is disconnected. It's not an ATS - but the controlled logic handles the genset.
Check with your electrical utility. They probably have a policy and diagrams for using standby generators for premise electrical systems that are connected to their power grid. Most are going to require an approved transfer switch and an inspection. These requirements are probably going to force you to comply with the current adopted version of the National Electrical Code and National Electrical Safety Code.
The comments insinuating that I am either a drunk or an idiot nothwithstanding, the question is whether the main disconnect disconnects the line from the load, which is what it does by definition. If the load is disconnected then there is no risk of back feeding the utility. If the load was connected, then there would be no occasion to set-up the back-feed.
It's also worth noting that it's permissable if not encouraged in some cases to backfeed the utility, such as net metering.
A well trained, alert operator could backfeed the house from the other subpanel by opening the main breaker first. But good engineering designs of such arrangements install key-interlock systems or other mechanical means to insure the main breaker cannot be shut the same time as the generator breaker. If you have a formal tagout/markup program that fulfills OSHA requirements, you might get away without mechanical locks. Even professionals with a lot of knowledge and experience take 'backfeeding' seriously.
But many incidents of damage and injury occur when a homeowner that doesn't know a lot about electricity tries to hook up their home with a portable generator.
The fact that you have to ask these questions would indicate you are in the latter group (don't know a lot about electrical installations), not the former (professional electrical engineer).
A variety of accidental things (not to impugn your competence or integrity, but humans make errors all the time), can lead to disasterous events. This is something you would do only rarely, under an elevated level of stress, with some percieved time pressures. These are just three human performance error traps that could contribute to error.
To help reduce human error, proper use of a well written procedure; pre-job briefing/review of key steps, potential errors and their consequences; and training in identifying human performance traps and tools you can use to avoid them.
Think about it. Die-hard professionals require interlocks on this type of setup. Does a non-professional *really* think he/she is less likely to make a mistake?
WRT net-metering, at least in the states, net-metering is *only* allowed with equipment specificaly designed to not 'island' or backfeed when the utility drops the power. The fact that you did *not* know even this speaks volumes.
My advice, yes it could work, and yes you could end up in a lot of trouble with the utility and the law if anyone ever gets hurt. You aren't an EE, so get someone who is to design a system that is *SAFE*.
Yes, and you need to phase and frequency match, etc. It isn't as simply as throwing a switch.
Yes, backfeeding as mentioned by the original poster is simply not smart and not safe and could well kill someone. There is just no good reason to do that when equipment is available to safely use auxiliary power generators.
What if you pass away, your home is sold, and the new owner fires up the generator without knowing that they need to flip the main breaker first?
Then a lineman gets electrocuited or the electrical system/generator gets fried when power returns. Or a fire is started.
Could this be a case for legal action against your estate or your family, should harm come to someones life or property?
In many cases, electrical codes protect YOU. In this case, they are protecting OTHERS as well as you.
From the following link: [A portable generator must be installed properly to protect electrical utility workers, family members and property. Improper installation of your portable generator and transfer switch system could void your HomeOwner's Insurance in case of accident or injury.]
The "grid-tie" inverters (approved for net-metering) must produce nearly perfect sinewave output as not to put junky waveform on the grid. Grid-tie inverters must be phase-locked (synchronized) with grid on a cycle-by-cycle bases, must use protective circuit to disconnect itself automatically during power outages (and not backfeed the utility during power outage conditions).
Without the automatic & failsafe backfeed protection circuits, small inverters & generators can literally "blow up" when the unprotected inverter/generator produced power ever meets grid power by accident! You would not want to be near the exploding generator/inverter when it happens! Should the gas tank in your generator decide to catch on fire, then you might burn down your house (and risk lives of your family members). Is it really worth it? I really don't think so.
I would recommend that you use the small generators & inverters for their intended purposes of powering some plug-in light stands, electric heater, refrigerator and a small electric range for cooking. I would place the generator outside (not in the garage!) at least 30 feet away from the house to keep away harmful exhaust fumes & prevent a housefire should the generator decide to catch on fire. Then I would run two separate extension cords (3 x 12 AWG, 15 amp type, 100 foot long) - one into kitchen & the other into the living room. One
15 amp circuit can power the refrigerator & electric range (you might have to disconnect the refrigerator while cooking as 120V, 15A might not be enough to power both appliances at the same time). Living room gets a separate 120V, 15A circuit for heater & lights. A 4000 to 5000 watt engine generator can provide some creature comforts during winter storm induced power outages (we had a 3-day power outage due to winter storm a few years ago).
By the way, you might not be able to even power microwave ovens & TV sets unless the generator produces clean sinewave. I get calls from customers who report that their microwaves & TV's in campers do not work with cheap 3000~5000 watt generators (sometimes, the spiky generator outputs would fry their appliances such as TV & microwaves). I know these thing because that's what I do for a living - providing power line conditioners & voltage regulators for customers worldwide!
We had an interesting effect of back-feeding in this area recently when the 11kV underground cable shorted out _AGAIN_. (The 5th patch to a 400 yard length in 18 months)
The SEB were backfeeding the 11kV local sub-network via some 240V pole-mounted cables. The cable sagged under the load and clashed together. Local residents were subject to cascades of molten copper dropping down onto the pavement!
Most states, when you sell a house you sign a piece of paper that states something like, "As far as I know, everything complies with local building code." Since he's been told repeatedly that a dangerous backfeed setup is
*not* code, he would have to perjure himself to sell it.
When the power is out, it is easy to become fairly desperate. DAMHIK. The manual or automatic transfer switch is the best solution.
Locating the generator at the pump house should work just fine. It will be a bit quieter than having the generator out the back door.
I WOULD PULL THE METER WHILE USING THE GENERATOR.
When the power company crews come through there would be no chance of feeding the service lines. It would be a simple matter of disconnecting the generator and reinstalling the meter.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG
Where I live they put a seal tag on the meter housing. You can't pull the meter without breaking the seal. I don't know if pulling it is illegal or not, but I'm sure the power company would be rather unhappy if they saw the seal broken and would likely investigate you for power theft.
Its electrically possible, but potentially deadly. You really need to put in an approriate bypass switch so there is NO chance that you will backfeed from the generator back to the utility.
MOST subpanels cannot be safely backfed (as I am sure you gathered from the other posts.)
BUT there are subpanels which are approved for: 1) have a 2 pole slot be used as a service feed; 2) havinging a second 2 pole slot be used as an alternative (e.g.: generator) feed; and 3) the manufacturer will sell or install an interlock so that only one of the two breakers is closed at the same time.
If you don't have such a panel, forget it. You might consider replacing it with a panel that can incorporated the interlocked feed breakers.
I was wondering why you need a separate panel with a manual transfer switch (this is the way they seem to be configured)? Couldn't you just hook up the generator to the main panel through a transfer switch (i.e line - off - generator, no subpanel)?
I know the danger of doing it this way is that you might pull too much current if all the circuits are on, but the generator has its own overload protection (and the circuits are still protected by the breakers). This would save on a lot of additional wiring, plus you could still overload the generator even if it is only powering specific circuits.
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