Problem Connecting Generator to Transfer Switch

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Old 11-10-11, 11:49 AM
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Problem Connecting Generator to Transfer Switch

I sure hope I'm not annoying you guys with all my questions about this generator. Thanks for helping me!

I installed a Reliance Controls TF151W single circuit transfer switch on my furnace circuit yesterday. The problem is that whenever I connect backup power to the transfer switch, the GFCI trips on the backup power source.

Here's my setup:

I have a Centurion/Generac 3250 Watt portable generator (Product Page - Centurion 3250 Watt Portable Generator Product Manual - http://www.centuriongenerators.com/M...DFs/0H2583.pdf)

The manual says (on page 6) "NEUTRAL BONDED TO FRAME" - I have a feeling that has something to do with my problem so I'm calling it out but I'm really not sure.

The generator does NOT have any GFCI protection.

I run power into my house with my "glorified extension cord" built like this (larger picture here: - http://i1195.photobucket.com/albums/...enDiagram2.png)


Then I run an extension cord from the generator powered receptacles (on the end of my glorified extension cord) to a Reliance Controls TF151W transfer switch (Product Page - TF151W Easy/Tran | Product Details | Reliance Controls Corporation Product Manual - http://www.reliancecontrols.com/Docu...structions.pdf).

Whenever I have the generator receptacles powered and plug into the transfer switch, the GFCI receptacles (that I installed) trip. I've plugged other things into those receptacles and it's fine and I've tested them and they each show 120 volts.

Also, as a test, I unplugged the extension cord from the generator powered receptacles and plugged it into a utility powered receptacle that's also GFCI protected (it was the closest one available) and the GFCI tripped on that receptacle too.

I've been reading about this but I need some help - I just don't understand enough about "neutral bonded to ground" or even if that's my problem. Since this setup was tripping GFCI receptacles, I was too afraid to plug it into a non-GFCI receptacle to see what would happen.

I have a call into Reliance Controls to talk to their tech support but they haven't called me back yet and I bet you guys are faster anyways.

What am I doing wrong here?

Thanks so much!
 
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Old 11-10-11, 12:57 PM
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I'm guessing that you accidentally have a neutral connected to a ground inside the reliance transfer switch or inside the furnace.
 
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Old 11-10-11, 01:01 PM
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I'll look over it again tonight but I opened everything up last night to double check my wiring and I remember seeing three white wires nutted together inside the transfer switch.

Are you saying that having GFCI receptacles is NOT the problem?

Thanks!
 
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Old 11-10-11, 01:07 PM
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Does the transfer switch connected to both ground and neutral in the main panel?
 
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Old 11-10-11, 01:11 PM
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The transfer switch is actually mounted at the furnace and not at the panel (I called Reliance and they said I could do that). So, the transfer switch connects to the ground and the neutral (and hot, too) that's supplied by the emergency power off/service switch for the furnace.

I hope that answers your question.
 
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Old 11-10-11, 01:23 PM
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I am not an electrician but my understanding is you cant have to bonded areas with GFI.

I will find the document link. I belive all you have to do is disconnect the bond jumper at the generator.

Why did you install GFI's???

OK anyway read this.

http://www.oshaprofessor.com/Portabl...rds%203-05.pdf

You should alsways follow local codes.

Mike NJ
 
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Old 11-10-11, 01:48 PM
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Thanks for the link. It's going to take me a little while to get through that and digest it.

In the meantime, Reliance support did call me back and the guy I spoke with said I am having a problem because of the GFCI receptacles.

I installed GFCI because .. well.. because I don't know better and in my mind, GFCI is safer than regular receptacles I guess. Plus, post #3 in my thread when I was building my "glorified extension cord" (http://www.doityourself.com/forum/el...ceptacles.html) said that GFCI was a good idea.

If you can't tell, I'm out of my league here and know enough just to be dangerous - but am trying to be safe!
 
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Old 11-10-11, 01:59 PM
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Quick question. That transfer swith is a 120v inlet???

Why are you not just plugging a extension cord from a 120 outlet on the gen to the 120 inlet on the transfer switch???

Your drawing shows a 4 wire twist lock and your link shows a 120 inlet transfer switch...

Mike NJ
 
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Old 11-10-11, 02:13 PM
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I didn't really want to run an extension cord through an open window or door - mostly because I don't have any windows that open or doors in my basement so I'd have to run a really long extension cord that would wrap through the house and down stairs. Also, if I were powering the furnace, it would be pretty cold outside so a cracked open window/door for the extension cord would let a lot of cold air in.

My "glorified extension cord" does go from the 220 outlet on the generator and splits it out to two 120 receptacles inside the house.

The transfer switch is a 120 inlet that gets its power from a standard 120 extension cord.
 
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Old 11-10-11, 02:20 PM
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So you wired a regular 4 prong inlet for the gen and wired that to two GFI outlets?

Then you take an extension cord and plug the transfer switch into one of those outlets?

Mike NJ
 
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Old 11-10-11, 02:27 PM
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That is correct. It goes from 240 volts at the 4 prong plug to 120 volts at each recptacle.
 
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Old 11-10-11, 02:44 PM
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After looking at the install sheet for the transfer switch, I would say the best thing to do is to use a regular receptacle instead of a GFCI for the side that will power the furnace transfer switch. The GFCI is not required there and because the transfer switch connects to a ground-neutral bond via the main panel it is incompatible with a GFCI device.
 
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Old 11-10-11, 03:38 PM
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Ibrooks but would he still have an issue when he plugs that extension into the transfer switch that the gen is bonded and that connection also will be bonded?

I always though dual bonds was a no,no....

Mike NJ
 
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Old 11-11-11, 08:16 AM
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Thanks for working through this with me, guys. I got it working - the problem was because of the GFCI receptacles.

I replaced the GFCI receptacles with standard receptacles and everything worked perfectly. I double checked all my voltage too and everything was reading 120 volts either from the generator or from utility power depending on how I had the transfer switch toggled.

I'll post some pictures in a few minutes just to show exactly what I have going on here.

Thanks again guys!
 
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Old 11-11-11, 08:49 AM
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Ok, here's the setup:

This is the generator receptacles on the end of the "glorified extension cord" and the location of the transfer switch:


Here's the transfer switch mounted to the side of the HVAC system:


Here's inside the junction box (under the transfer switch) that shows the wiring between the utility power, transfer switch, and the furnace:
 
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Old 11-11-11, 08:57 AM
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Last question!

Would you recommend that one of the receptacles (the one that won't power the transfer switch) be GFCI? Is there a good reason to either use or not use GFCI in this application?

Thanks so much!
 
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Old 11-11-11, 10:03 AM
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If you are more comfortable with a GFCI replace one receptacle with a simplex non GFCI receptacle. By using a simplex you reduce the likelihood of a non GFCI being used by other then the furnace but off course you go from four available receptacles to three. I won't discourage you from taking all safety precautions you feel are reasonable so I won't say no GFCIs.
 
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Old 11-12-11, 07:54 AM
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Your problem is with the generator and where you said neutral bonded to frame. I bet your transfter switch to the furnace only switches the hots and not the neutral. You would need to remove the neutral bond on in the generator for the gfci's not to trip, also you should only have one neutral bond when connecting a generator to a house system otherwise a potentially dangerous situation could occur and you could get zapped by the generator frame if voltage gets fed back through the neutral (worn wires etc). There should only be a neutral bond in the main panel (the ground and white wire you ran from the transfer switch to the main), you also dont want one on the generator.

However: If the generator is going to be used "standalone" not plugged into the house you will need to put the neutral bond back on the generator.

Here is a good link for you:

Portable generator neutral rewiring
 
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Old 11-12-11, 08:11 AM
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I forgot to mention that you did say it was not wired to the main panel.... but you still connected the ground and neutral from the transfer switch to the wiring at the boiler.... which goes right back to the main panel and therefore there are two neutral bonds one at the panel through the wiring from the boiler and one at the generator. GFCI will trip.
 
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Old 11-12-11, 11:36 AM
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+1. what hammerdown said.

Aonther way to say it:

The reason the GFCI's were tripping is because you are paralleling the ground and the neutral because both are joined at the main Panel AND at the generator. That means you have some current on the ground wire. The GFCI's were working like they are supposed to when they sense current on the ground wire.

The easiest fix is to remove the bonding jumper in the generator.
 
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Old 11-12-11, 05:14 PM
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hey JFINN- I've got a homelite 5000 neutral bonded generator and have been studying thes issues carefully-try to GOOGLE- HOME GENERATOR INSTALATION-(members.rennlist)-This guy really knows what we need to wire our neutral bonded generators-another good webpage is PORTABLE GENERATORS AND OSHA CONSTRUCTION REGULATIONS( GRIZZY) YOU'll find that your generators bonded neutral must have the neutral switched (Gentran sells a "switched neutral kit" $100)at the transfer switch to facilitate only one ground at a given time-cant have the service panel grounded and the generator grounded at different points at the same time with GFIC-The GFIC detects a difference in impedence and trips .One ground at any given time-You could unbond-or its called isolate the neutral bond at the generator-this would give you a floating neutral-carefull and find someone who know exaclty how to do it on your generaator- this alone could fix your problem- disables your GFIC- must be reconnected if its put back as a stand alone generator to be OSHA compliant-Hope this helps and remeber saftey is always the most important thing-Also I belive someone on YOUTUBE put the exact same switch for a furnace as you did- shows exactly how he did it-might help you retrace your wiring for any errors
 
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Old 11-12-11, 09:14 PM
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Thanks guys. I removed my GFCI receptacles and put in standard receptacles and everything worked but from what I'm reading here it's not safe this way.

Safety is important to me but how dangerous is this? It'll only be used a couple of times a year (when the power goes out - hopefully no more than once or twice). I'm hesitant to remove the neutral bond from the generator because I need that in place to properly power the other receptacles that I'd plug things like a fridge/lights into that don't go through a transfer switch - sounds like with my setup I can only power the furnace with the transfer switch (after removing the neutral bond from the generator) or power the regular receptacles to power the refrigerator/lights (after putting the neutral bond back in place).
 
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Old 11-13-11, 11:20 AM
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You can add the ability to also switch the neutral on several Transfer Switches. You could check into this and see if that can be added to your Transfer switch. This would allow you to power both the furnace via the Transfer Switch and other appliances via extension cord without having to remove the bound in the generator.
 
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