jim282
I have a model 4721 gen, ser # 4014015 and a new 200 amp service rated Generac transfer switch. A local authorized Generac installer wired it up but the generator will keep running when utility power comes on. He said he was going to study the wiring diagrams to see what is wrong and get back to me but I figured I would ask this question here to try to get a heads up. Any suggestions?

P/S - I don't know the transfer switch model but i spoke with Kelly from Ziller and gave him the model and serial number and he sold me the switch. Thanks for any input.

JIM
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MikeCB
jim282;37430 wrote:
i have a model 4721 gen ser # 4014015 iand a new 200 amp service rated generac transfer switch. a local authorized generac installer wired it up but the generator will keep running when utility power comes on, he said he was going to study the wiring diagrams to see what is wrong and get back to me but i figured i would ask this question here to try to get a heads up. any suggestions? p/s i don't know the transfer switch model but i spoke with kelly from ziller and gave him the model and serial number and he sold me the switch. thanks for any input. JIM


Make sure the N1-N2 and T1 wires are not mixed up. N1-N2 are your sensing wires off of the utility side. T1 is for charging and accessories off of the generator protected side.

If mixed up it is possible for the generator to get its 240 sensing voltage from N1-T1, or, N2-T1 (depending on the mix-up)..... All will act normal and transfer during an outage. However, when power is restored the generator is basically never going to see 240v since T1 is disconnected from utility once a transfer occurs.

Edit::: it is most likely that N1 & T1 are the ones that are flip flopped. Mixing up N2 & T1 would cause the generator to run all the time ..... Either way, have your guy check all his connections of those wires at all points between the switch and the genset. Ring them out if he must. Also check the factory installed wires at the points of connection. Make sure they didn't mix them up there from the factory. The designations should be printed on the wires themselves..... If you can read them.
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MEC
Have him check the load side of the main breaker. Behind the buss bars.
There are two stakons there for N1 & N2 and if one has fallen off the generator will runaway.

I check stakons on every install as I found some are very loose and will fall off.
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MikeCB
MEC;37432 wrote:
Have him check the load side of the main breaker. Behind the buss bars.
There are two stakons there for N1 & N2 and if one has fallen off the generator will runaway.

I check stakons on every install as I found some are very loose and will fall off.


^^^ that too.:D. Although that would just make it want to run all the time. I read the OP as, "all is normal until utility power is lost, then restored"
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MEC
Yes, sometimes it's hard to interpret what the OP is saying.

Should be pretty easy to troubleshoot in any case.
You should have 240 at the generator on N1 & N2.
Pull the T1 fuse and it should indicate on the controller.
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Peddler
Your generator requires N-1, N-2, T-1 and T-2 as well as 23 and 194. You will have to add a fuse block to the transfer switch for T-2. Lacking this however, if the others are hooked up correctly, the unit should still shut off after transfer. The T-1 and the T-2 keep the exercise program alive when you are under generator power. As was mentioned the line voltage wires could be crossed or fuses blown, otherwise you have a control board problem. Good Luck
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MEC
Good catch with the T2. When he said new transfer switch I just assumed a new generator.
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