A contractor wants to wire a Generac generator to a home using a manual interlock in the panel,instead of an automatic transfer switch.The customer is trying to save money.When power goes out, the generator will come on automatically,but the power will not be transferred to the panel until the customer manually engages the manual interlock in the panel and then select the loads they want to run.Is there any code issues with this type of set up?I have never seen it done with an automatic generator.Any relevant code numbers will be appreciated.
Generator
- Thread starter jtom
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Hendrix
Senior Member
- Location
- New England
How would the generator come on automaticly without a transfer switch?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
My question as well. Without the ATS one would need to rig their own power monitor to automatically start the generator, why would you automatically want to start it if it will not automatically transfer? Use a manual control method to start the generator if not automatically transferring is my suggestion.
ceb58
Senior Member
- Location
- Raeford, NC
The generator uses N1 N2 as utility sensing to start the generator. When he flips the interlock the generator will see power and shut down. The only way to avoid this is to feed N1 N2 from a source that will not receive power from the generator.
kwired
Electron manager
- Location
- NE Nebraska
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- EC
Not aware of just how all generators/ATS perform but doesn't the ATS usually monitor incoming power and then send a start signal when necessary to the generator using a control voltage originating from the generator unit battery? If that is the case then not installing the ATS means you would need to use alternate control device to send this start signal to the generator unit, could possibly be a simple toggle switch located near the manual transfer switch, but you have to connect something before you would get any kind of start signal, or start it from any manual controls already in the generator control panel itself.
ceb58
Senior Member
- Location
- Raeford, NC
In the new units the control panel senses utility from N1 N2. When it drops power the genrator will start and send a 12v signal back to the ATS to switch to generator power.
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
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- Roanoke, VA.
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- Sorta retired........
So the generator is sensing utility? Where do you connect N1 and N2? In front of the main?
So when power comes back on the genset shuts down and nothing gets power until someone retransfers the interlock?
I would never set something up like that.
Last edited:
qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
It will be interlocked, but most of them are not UL listed.
Sounds like he's talking about a Interlock Panel Cover with a generator breaker in circuit 2&4 where you have to shut off the Main to be able to engage the backfed generator panel.
Problem would be the controls for the starting and stopping of the generator without the ATS.
Not sure whats going to verify that the generator actually ever started,what would keep the generator from cranking endlessly if it didn't start, or if it did start if the voltage was correct, and if after you transferred the breakers manually what would shut it down.
By the time you built your own controls to do all of this, to me, the ATS starts sounding much less expensive by the minute.
<JAP>
Problem would be the controls for the starting and stopping of the generator without the ATS.
Not sure whats going to verify that the generator actually ever started,what would keep the generator from cranking endlessly if it didn't start, or if it did start if the voltage was correct, and if after you transferred the breakers manually what would shut it down.
By the time you built your own controls to do all of this, to me, the ATS starts sounding much less expensive by the minute.
<JAP>
Exactly right, along with several other things that a ATS does to insure everything is as it should be prior to the load being transferred on or off.
<JAP
kwired
Electron manager
- Location
- NE Nebraska
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- EC
How does such units get used if there would be a manual transfer switch? I haven't done a lot of generators, but those I have done usually the ATS does the monitoring and tells the generator when to start and stop. Use a manual transfer switch and you just use manual controls on the generator to control it.
ceb58
Senior Member
- Location
- Raeford, NC
If the OP is referring to the small Generac units the "Brains" are in the control panel on the generator. When power drops on N1 N2 it starts and sends a signal back to a relay that switches the contactor in the ATS.
The OP has two problems.
A contractor that has no clue and a cheep customer. The only way would be to install a DP breaker between the meter and main disconnect to supply power to N1 N2. I can see many problems with this type set up. If no one is home and utility is lost the generator will run but no one is there to switch the interlock. Same thing in reverse, if they are running on generator and they leave. Utility back on gen. shuts down no one there to switch back to utility. All this to save $700.00 or less, if bought as a package, on an ATS.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Again I have not installed all that many of these systems but don't these units have any kind of manual method of locking them out or do you need to disconnect the battery to keep it from starting? For a situation where connected to a manual transfer switch you would want it to still keep battery charged as well as operate an engine block heater if it has one, but have the ability to have control switched to "OFF" instead of in a standby mode. This may possibly mean you lose any automatic exercise features though and would have to manually exercise the unit. I'd guess the majority of units are connected to an ATS, but there probably are some that get manual switches installed for various reasons.
lakee911
Senior Member
- Location
- Columbus, OH
Generac has the power monitoring brains inside the generator and the generator in turn calls the ATS to transition. What very few folks will tell you is that the Generator can be made to operate in a more typical two wire fashion. Your Generac dealer can get you a couple of wires with pins crimped that plug into the factory generac harness and they'll fire the generator on a contact closure.
I've got mine set up this way. I flip a wall switch and generator fires up and then I use my interlock kit to manually transfer power.
I've got mine set up this way. I flip a wall switch and generator fires up and then I use my interlock kit to manually transfer power.
So what happens if someone who doesn't know any better flips the switch and the generator starts cranking but fails to start?
does it just keep cranking until the battery gets low enough that it burns to the ground?
What safety interlock is there in place to keep the generator in this scenario from continual cranking should it not happen to start?
<Jap>
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I think that is handled by the way the external jumper leads cross connect the signals to and from the Generac controller. Instead of the decisions being made by external equipment, the run signal output from the generator can be used to kill the starter and to keep the generator energized after the internal cranking timer expires.
What you probably do not get is multiple attempts to start as a result of one switch closure.
Optimal operation requires an intelligent hand on the switch, but it would still be fail safe if the switch is just turned on.
Well at least that part of it's good to know.
Probably would be more failsafe if they would extend a generator pull-cord through on outside wall to start it and instead of a start switch mounted next to the interlock panel they could intall a generator kill switch much like the one I had on a 5 HP briggs and Stratton go cart I had when I was young.
Jap>
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
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