ceb58
Senior Member
- Location
- Raeford, NC
Agreed, most have a 3 to 5 crank cycle. If it doesn't sense sufficient RPM's it will go into lock out on over crank.
Generator
- Thread starter jtom
- Start date
- Status
Agreed, most have a 3 to 5 crank cycle. If it doesn't sense sufficient RPM's it will go into lock out on over crank.
lakee911
Senior Member
- Location
- Columbus, OH
Yes, I believe that's the case with two wire start too. I'll kill the gas someday and give it a try.
ken44
Senior Member
- Location
- Austin, TX
Optional Standby Systems-NEC 702
Optional Standby Systems-NEC 702
I set up something similar to this for a customer years ago, they had one server that was backed up by a UPS that would give them about 1 hour to bring in their own trailer-mounted generator and tie it into the emergency box that I provided. They had to unplug the server from the normal power box and connect it to the emergency power box, then flip the selector switch over to emergency power. This prevented them from backfeeding the utility, it provides for their needs and they didn't have to pay for an ATS or the upkeep of an ATS and they don't have a permanent generator anyway, nor did they want one.
In the case of a homeowner, I would be leary about a manual transfer switch unless the person works from home or stays at home since you could lose refrigerated items if you were gone during an extended power outage.
Optional Standby Systems-NEC 702
I set up something similar to this for a customer years ago, they had one server that was backed up by a UPS that would give them about 1 hour to bring in their own trailer-mounted generator and tie it into the emergency box that I provided. They had to unplug the server from the normal power box and connect it to the emergency power box, then flip the selector switch over to emergency power. This prevented them from backfeeding the utility, it provides for their needs and they didn't have to pay for an ATS or the upkeep of an ATS and they don't have a permanent generator anyway, nor did they want one.
In the case of a homeowner, I would be leary about a manual transfer switch unless the person works from home or stays at home since you could lose refrigerated items if you were gone during an extended power outage.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
How long do you consider extended outage? Refrigerators will stay cold for several hours if the doors are not being opened, unless there is little or nothing in them -then there isn't much to lose anyway.
ken44
Senior Member
- Location
- Austin, TX
Extended Power Outage
Extended Power Outage
IMO, a 2-4 hour time from for restoration of utility power to a residence is normal for our area which is central Texas, once it gets beyond 4 hours people start to get very concerned about their refrigerated items which can easily take hundreds of dollars to replace and if it is during the middle of the day in the middle of the summer, it becomes esclated to the point that the comfort of indoor pets also become an issue. Now, for the commercial facilities that I manage, there are walk in coolers that contain millions of dollars in pharmaceutical products, therefore, they have ATS's and well-maintained generators.
Extended Power Outage
IMO, a 2-4 hour time from for restoration of utility power to a residence is normal for our area which is central Texas, once it gets beyond 4 hours people start to get very concerned about their refrigerated items which can easily take hundreds of dollars to replace and if it is during the middle of the day in the middle of the summer, it becomes esclated to the point that the comfort of indoor pets also become an issue. Now, for the commercial facilities that I manage, there are walk in coolers that contain millions of dollars in pharmaceutical products, therefore, they have ATS's and well-maintained generators.
This is a completely different scenario than what the OP was talking about.
The above is not an Auto-Start Generator with a manual panel cover interlock situation.
The above requires someone to physically start the generator that's on the Trailer and hook it to the Emergency Box.
Although I don't see why one wouldn't just extend the loadside of the emergency box to a receptacle by the server if you were going to do the unplug and plug thing and forget the selector switch , but I don't know the exact application.
JAP.
Generac has built in safety controls in the control panel of the generator. The generator will shutdown if something isn't right. These control panels are pretty smart and sensitive. The ATS really does nothing that you couldn't do manually.
I would do this by feeding n1 and n2 off the main panel and then having a sub panel with an interlock kit for my backed up circuits. Power goes off, the generator starts. You transfer. Power comes back on the generator turns off, you transfer back.
I would question how much I'd be saving though...
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
But that is what we are trying to avoid - loss of power and the generator starts, but does no good if nobody is there to transfer. Would also shut generator down after power is restored, but again nobody there to transfer back to utility power. Somehow there needs to be a way (and there probably is) to disable the auto control and manually start/stop that generator.
GeneratorLink
New User
- Location
- Port St Lucie, FL, USA
Hello, first time poster long time lurker. I am an electrical engineer with 15 years in the generator business. The first question I'm asking is why you want the generator to auto-start in the first place if you're using it in a manual transfer configuration. You would be better off setting the generator to manual start, too.
I've seen a few customers try to do this kind of thing, sometimes to save money on an ATS, but usually to avoid installation difficulties of that ATS. With Generac products, the ATS is basically super-cheap (almost free) when purchased with the generator. More than likely there are problems installing the ATS which would cost way more than $700. For example, some AHJs down here in Florida require the genset amperage to match the panel amperage when an automatic transfer switch is used (does not apply to manual). We complain about that, but they won't budge. But it is true that going manual will alleviate the inspector's concern.
This has little to do with NEC and more to do with Florida inspectors seeing crappy genset installers installing gensets that are too small and then the owner complains to the inspection dept.
I've seen a few customers try to do this kind of thing, sometimes to save money on an ATS, but usually to avoid installation difficulties of that ATS. With Generac products, the ATS is basically super-cheap (almost free) when purchased with the generator. More than likely there are problems installing the ATS which would cost way more than $700. For example, some AHJs down here in Florida require the genset amperage to match the panel amperage when an automatic transfer switch is used (does not apply to manual). We complain about that, but they won't budge. But it is true that going manual will alleviate the inspector's concern.
This has little to do with NEC and more to do with Florida inspectors seeing crappy genset installers installing gensets that are too small and then the owner complains to the inspection dept.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
And if proper load calculation is done and it is applied properly, there is no good reason for the genset to be too small, thumbs down to the lazy inspector.:thumbsdown:
- Occupation
- Licensed Electrician
I say thumbs down on the whole rule that requires sizing a generator to carry the calculated load of a house. It is a design issue and nothing more. The NEC should keep their nose out.
If I want a back up generator to come on automatically when I'm off on one of my frequent vacations just so the meat in my freezer won't spoil, the motion sensor lights will work and the gas furnace will run I should not be forced to buy a generator large enough to run my electric double oven, coffee pot, microwave, hair dryers, and the calculated sq foot VA of the whole house when I'm not home.
If I want a back up generator to come on automatically when I'm off on one of my frequent vacations just so the meat in my freezer won't spoil, the motion sensor lights will work and the gas furnace will run I should not be forced to buy a generator large enough to run my electric double oven, coffee pot, microwave, hair dryers, and the calculated sq foot VA of the whole house when I'm not home.
- Location
- Massachusetts
Now Dave, I know you will be surprised at this but it was generator manafactures just trying to save your food from spoiling if you under paid for .... err ... I mean undersized your generator.
You should be thanking them from protecting you from yourself.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I can agree with that also, one other place where NEC does not follow it's own guidelines set in 90.1.
Legally required standby generator - more understandable for it to be able to handle the calculated load - but IMO in those instances the calculated amount of load should really be determined more so by the code/standard legally requiring the standby generator then by the NEC.
Let the other applicable standard be the design standard, not the NEC.
- Occupation
- Licensed Electrician
What nice folks. It's about time big business stopped being all about the money. It's good to find some out there that really care about people.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I do not think that the NEC requires that a whole house generator be sized to carry the full calculated load.
What I do see is that if there is an Automatic Transfer Switch (ATS), then either the generator must carry full load or there must be load shedding hardware installed in conjunction with the ATS.
If you do not want to go for the expense of load shedding and you need to have an ATS for unattended operation, the simple solution is to put the critical loads on a sub panel with the ATS located on the feeder and with the generator sized to handle the calculated loads on that subpanel only.
The NEC is not telling you what size generator you need to install, just what else you have to do if you choose to install a small one compared to the calculated load.
What I do see is that if there is an Automatic Transfer Switch (ATS), then either the generator must carry full load or there must be load shedding hardware installed in conjunction with the ATS.
If you do not want to go for the expense of load shedding and you need to have an ATS for unattended operation, the simple solution is to put the critical loads on a sub panel with the ATS located on the feeder and with the generator sized to handle the calculated loads on that subpanel only.
The NEC is not telling you what size generator you need to install, just what else you have to do if you choose to install a small one compared to the calculated load.
- Location
- Massachusetts
How about the NEC just stay out of it as they had for a 100 years?
- Occupation
- Licensed Electrician
Then I should not have to.
If I'm home I can do my own load shedding. I have a house with gas heat and no air conditioning. The biggest loads I have are my toaster, microwave, coffee pot, electric oven, electric dryer, hair dryer, fridge, and a freezer. If I'm away all but the last two are shedded without any extra hardware.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Again design decisions here. If generator is automatically transferred to load - it will trip overcurrent device if load is too much - this is what code is about preventing that overload, keeping the refrigerator from warming is a design decision and a wise approach at that is to ensure the transferred load is within limitations of the overcurrent protection. Some legally required standby systems is more understandable to require a certain design - but should be a requirement more from the code mandating the standby system then from the NEC itself, and I think in most instances this is true - any NEC requirements are just mirroring other NFPA codes in this area.
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