How to add the generator power input to the switch

[youbet]

I really liked the idea of the $85 manual transfer switch mentioned earlier in the thread and was considering ordering one. So, I did some further investigating.

It's a Reliance Controls Easy Tran TF, model number TF151W. They are readily available on ebay. I was going to order one until I was able to find and read the instruction manual online. It's really designed to mount next to the service panel and it leaves the neutrals (white wires) tied together whether using the power from the service panel or from the generator.

I was hoping to find it to be a 3 pole double throw switch that actually completely switches the hot, neutral and ground from the panel input to the generator input when the switch is activated, but it's not and it doesn't. After reading that, I feel safer with a plug and receptacle mounted on a joist above the furnace. It will still be a dedicated circuit to the furnace using a single rather than a duplex outlet. That way the furnace would have to be unplugged before anything else could be plugged in, and thus no worries or fear about an overloaded circuit.

If I was going the transfer switch route, the only switch I was able to find that would do what I want it to do is called a "100 AMP Disconnect Knife Switch 3 Pole Circuit Breaker for back up generators" that I found on ebay. This is truly a 3 pole double throw switch for a mere $23.00 if anyone is interested.

Very interesting freedomatlast. I don't understand the downside of the way they're doing it but since you've called out that having a 3PDT switch is important, I'll have to go try to research that.

This is the description of the product as they give it:

The Easy/Tran TF transfer switch is designed for the control of a single circuit, such as a forced-air furnace, in the event of a power failure. The attached 18" flexible aluminum conduit is pre-wired and allows the TF to be easily connected at the circuit breaker panel or the furnace or at any point in between. Power can be supplied from a portable generator, inverter, RV generator, fuel cell or any standby source capable of producing sufficient current to operate the desired load. Uses standard grounded extension cord.

They say it can be connected at the furnace and I was picturing it replacing the existing on/off switch mounted on my furnace.

 

[freedomatlast]

Why is that an issue for you?

Think for a minute if this is installed in a house where some ammeter did some wiring and the polarity has been reversed........

It really doesn't cost much more to produce a 3 pole double throw transfer switch that truly isolates the entire circuit. I know the linemen that are restoring power after a storm with portable generators on everywhere would appreciate it.

 

[freedomatlast]

Very interesting freedomatlast. I don't understand the downside of the way they're doing it but since you've called out that having a 3PDT switch is important, I'll have to go try to research that.

This is the description of the product as they give it:



They say it can be connected at the furnace and I was picturing it replacing the existing on/off switch mounted on my furnace.

Yea, that's what I was thinking of doing too. Google "instructions for TF151W" and you'll see how it's configured. Or click the link provided...

TF151W Easy/Tran - Reliance Controls Corporation

Click the tab for "Installation Help and Manuals"

 

[youbet]

Yea, that's what I was thinking of doing too. Google "instructions for TF151W" and you'll see how it's configured. Or click the link provided...

TF151W Easy/Tran - Reliance Controls Corporation

Click the tab for "Installation Help and Manuals"

This gets more and more interesting! I see that they have two models: The TF151 is for mounting at the furnace and the TF151W if for mounting at the electrical panel.

I went downstairs and noticed that my furnace on/off switch has a GFI duplex outlet mounted in the same duplex box. Now I'm no longer sure whether I would go for mounting at the furnace or mounting at the electrical panel.

I'm still not sure why you're concerned about the neutral line not being opened when throwing the switch from line to generator. I'm not saying you're wrong. I just don't understand how leaving the neutral attached could lead to back-feeding or what other problem it might cause.

I saved the manual to my desktop for additional head scratching later........ Thanks for the link!

 

[ERD50]

Quote:
Originally Posted by travelover View Post
When I had my furnace replaced, the techs said they had to convert it back to being hardwired. As soon as it passed inspection, I wired it back to a plug in.

So, it is really against code.

Now, what is the rationale? I can't think of a safety reason. Look on the Web, and found this.

Quote:
According to NEC’s section 400.7 code requirement, you shouldn’t use flexible cords and cables for furnaces. That’s why these appliances usually leave the factory hardwired without a flex cord or an attachment plug.

The NEC is against plugged-in furnaces for a good reason: they consume so much electricity that they need a dedicated circuit. When you have a plug-in furnace, you’re likely to plug it into a shared outlet with other appliances. As a result, the circuit gets overloaded, damaging the furnace and the other plugged-in electrical devices or even resulting in a fire.

But there's always a risk of overloading a circuit with plug-in appliances. The place this most likely happens is in the kitchen, when people plug in too many appliances at a time. That's what the circuit breaker is for.

And in this case, you are plugging the furnace into its own dedicated circuit that it is not sharing with anything.

That does seem odd. The part that makes sense is that a furnace motor does draw enough that it should be on its own circuit (and to avoid another device tripping the breaker and leaving you w/o heat).

But that's true of my Ejector pump too, and they just use a single outlet for it, so you can't plug in anything else. Seems that should be fine for a furnace. At my previous house, I did the cord and receptacle thing, but just used a duplex since they were handy and I didn't really give it a thought. I wasn't going to plug in anything other than a temporary shop light in that space. When the installers replaced the furnace, I asked them to use the cord from the old, and they did w/o question. And they seemed very professional, did a very nice job overall.

-ERD50

 

[ERD50]

Think for a minute if this is installed in a house where some ammeter did some wiring and the polarity has been reversed........

It really doesn't cost much more to produce a 3 pole double throw transfer switch that truly isolates the entire circuit. I know the linemen that are restoring power after a storm with portable generators on everywhere would appreciate it.

Side note: Interesting typo/auto-correct! "ammeter" for "amateur" - the context fits! And I always have trouble spelling "amateur".

So I did think about it for a minute, and I think the single pole switch is safer.

First, consider that circuit breakers open only the hot line (except for 220 in the US, that's two hot lines, so both are opened). So that's how it is commonly and safely done.

OK, what about a hot/neutral miss-wire? Seems to me, a single pole switch is safer.

If the H/N is swapped in the transfer switch on the generator side, when it's plugged in and running, the Gen Hot would be connected to the panel Neutral, so connected to Ground at the panel - instant short circuit, and the generator Circuit Break opens. Safe.

If all three are switched, a miss-wire of H/N in the transfer switch could send a reversed H/N to the furnace. The generator wouldn't see it as a short, as it's N/G are still tied, they just got reversed going to the furnace. Now you have a furnace with a lot of metal parts that might be electrically hot. Not safe!

At least that's what I see from a quick sketch, I think I got it right though.

-ERD50

 

[homestead]

Think for a minute if this is installed in a house where some ammeter did some wiring and the polarity has been reversed........

It really doesn't cost much more to produce a 3 pole double throw transfer switch that truly isolates the entire circuit. I know the linemen that are restoring power after a storm with portable generators on everywhere would appreciate it.

I see you are concerned about safety. For best safety hire an electrician to wire it in. You can also turn off the main breaker on your electrical panel which will prevent anything from going out to line when using the generator.

 

[freedomatlast]

I see you are concerned about safety. For best safety hire an electrician to wire it in. You can also turn off the main breaker on your electrical panel which will prevent anything from going out to line when using the generator.

Great discussion and lots of good ideas and things to think about.

The issue with turning off the main breaker is you won't know when the power is restored.

That's why I like to completely and totally isolate the power (H, N & G) from the generator and the circuits powered by it, from the service panel and the circuits powered by it.

I appreciate your advice and concern on using an electrician. The fact is I've never used an electrician for anything. I've completely installed brand new electrical service in dwellings starting from the weather head and service mast, down through the meter base, installed the service panel and wired all the circuits. Always passed inspection first time and usually complimented in the neatness of the job. All the electric company does is makes the service connection and plugs in the meter. The learning and satisfaction that comes from a DYI job well done, is hard to beat. Also a big factor in financial freedom.

 

[ncbill]

If the furnace has a dedicated circuit that is only wired to a single outlet in a closet, and the furnace is the only thing plugged into that outlet, how do people plug any additional load to it?

I saw that a poster suggested that someone may still plug an extension strip to that single outlet and manage to overload it. But, but, but can't they overload any outlet with an extension outlet strip? Why pick on the furnace outlet? What is so special about it? Maybe the circuit breaker will trip, the furnace does not run, and people freeze to death?

Youse guys forget that the utilities have no problem with power turning off to millions of people, and they froze to death all the time. Or they have their plumbing all frozen up, and their house all flooded and ruined when it warms up. Silly furnace wiring code does not do anything for them there.

The standard duplex outlet downstream of the switch next to my forced-air furnace has the condensate pump plugged into it...furnace (hardwired) & pump are all that's on the circuit.

Soon my furnace will be plugged in there as well since it's clear there's no code requirement, just a recommendation it be hardwired.

Together I'm sure they don't use as much power as my over-the-range microwave (also on its own dedicated 20A circuit) so all this talk of overloading the circuit makes no sense to me.

 

[38Chevy454]

All this talk about the neutral being switched or not: the neutral is connected to ground in your breaker box. Not at the plug or whatever receptacle. Point being there is no way to backfeed the line for the repairmen on the neutral. So it doesn't really matter if you use a switch to disconnect the hot wire only, or a double throw switch and disconnect both hot and neutral.


The simplest and easy fix as discussed is just convert your furnace lead to a male plug, remove the current switch and install a female receptacle in the hardwired box. When you lose power unplug the furnace lead from the hardwired box and plug it into the generator extension cord. Now your furnace will work and keep your house warm.

 

[CRLLS]

This may be a different subject, my portable 5,500W genny will trip a gen-mounted GFCI when the ground from the gen is connected to the house ground. I have to disconnect the gnd wire in the extension cord to get it to work. I could mod the generator. I looked into it and I would have to permanently make the change but choose not to do so. Just be prepared for this possibility regardless of using a suicide cord, adding an interlock or a bypass switch.

 

[freedomatlast]

The simplest and easy fix as discussed is just convert your furnace lead to a male plug, remove the current switch and install a female receptacle in the hardwired box. When you lose power unplug the furnace lead from the hardwired box and plug it into the generator extension cord. Now your furnace will work and keep your house warm.

Agreed. Exactly what I suggested in detail way back in post #24.

 

[NW-Bound]

This may be a different subject, my portable 5,500W genny will trip a gen-mounted GFCI when the ground from the gen is connected to the house ground. I have to disconnect the gnd wire in the extension cord to get it to work. I could mod the generator. I looked into it and I would have to permanently make the change but choose not to do so. Just be prepared for this possibility regardless of using a suicide cord, adding an interlock or a bypass switch.

Inside my whole-house electric panel, all the ground wires and neutral wires are tied together. I believe this is the norm for all installations.

That being the case, the genny GFCI definitely will not like it, because it sees some current flowing on its ground wire, due to the above connection. With the ground and neutral tied together both inside the genny and at the house electric panel, the ground and neutral wires connecting the genny and the house are wired in parallel (their end points tied together at both ends), and each carries 1/2 the current.

Hmmm... This is a dilemma. How to solve it? Perhaps the thing to do is to disable the genny GFCI, and rely only on the house GFCIs.

 

[OldShooter]

Agreed. Exactly what I suggested in detail way back in post #24.

I'll claim my post #9.

 

[ERD50]

Originally Posted by CRLLS View Post
This may be a different subject, my portable 5,500W genny will trip a gen-mounted GFCI when the ground from the gen is connected to the house ground. I have to disconnect the gnd wire in the extension cord to get it to work. I could mod the generator. I looked into it and I would have to permanently make the change but choose not to do so. Just be prepared for this possibility regardless of using a suicide cord, adding an interlock or a bypass switch.

Inside my whole-house electric panel, all the ground wires and neutral wires are tied together. I believe this is the norm for all installations.

That being the case, the genny GFCI definitely will not like it, because it sees some current flowing on its ground wire, due to the above connection. With the ground and neutral tied together both inside the genny and at the house electric panel, the ground and neutral wires connecting the genny and the house are wired in parallel (their end points tied together at both ends), and each carries 1/2 the current.

Hmmm... This is a dilemma. How to solve it? Perhaps the thing to do is to disable the genny GFCI, and rely only on the house GFCIs.

Yes, as you say, with two Ground Neutral bonds, the Neutral current is split between Neutral and Ground, so Hot current does not equal Neutral current, and GFCI does it's thing and disables the connection.

I found a discussion on this, (I'll try to find the link later), the manufacturer said you need to disconnect the Ground bond at the generator, and label it so that no one uses it away from a house w/o that ground bond. If used stand-alone, you need that bond, but you don;t want two of them.


CRLLS - make sure you do this correctly for your specific model, it could be very dangerous if not.

edit: here's the link:

https://www.diychatroom.com/threads/gfci-on-generator-tripping-home-backup.47903/

Below is the reply I got from Wacker Neuson.

Thanks for the guidance. It looks like I'm on track now.

----------------------------------------------------------------------------------------
The neutral - ground jumper wire on the generator will have to be
removed to prevent the nuisance tripping of the GFCI.

Your house should already have its neutral bonded to ground so this
still meets requirements of the National Electric Code (NEC).


Your Wacker Neuson dealer can sell you a kit p/n 0164835 that contains
these instructions and stick-on labels that warn the generator now has a
floating neutral.


NOTE: If you ever disconnect the generator from the house and use it for
other purposes, you MUST re-connect the neutral - ground jumper on the
generator!

If you (or the next owner of the generator) do not intend to re-connect
the generator to the house again... then you may also remove the
floating neutral labels.

-ERD50

 

[a60dan]

This is the right and safe way to connect a generator to the furnace.

 

[Jerry1]

Inside my whole-house electric panel, all the ground wires and neutral wires are tied together. I believe this is the norm for all installations.

My house is wired like that too. I had a new panel installed when I moved into this house. It passed inspection at that time (about 5 years ago). However when the pool installer electrician came to do his run to the pool, he said that code is the separate the neutral from the ground. He basically said that my panel wasn’t done right. I told him to just install his run and not worry about it given that I had the inspection sign off right on the panel from less than 5 years ago at that time.

So, I don’t know what code is, but it might be that now you need separate ground from neutral.

 

[Dash man]

So, I don’t know what code is, but it might be that now you need separate ground from neutral.

We bought a townhouse for my son last year that was wired like that. The inspector said it wasn't up tp code. We got an electrician to fix it when he came out to do some other work.

 

[CRLLS]

Yes, as you say, with two Ground Neutral bonds, the Neutral current is split between Neutral and Ground, so Hot current does not equal Neutral current, and GFCI does it's thing and disables the connection.

I found a discussion on this, (I'll try to find the link later), the manufacturer said you need to disconnect the Ground bond at the generator, and label it so that no one uses it away from a house w/o that ground bond. If used stand-alone, you need that bond, but you don;t want two of them.


CRLLS - make sure you do this correctly for your specific model, it could be very dangerous if not.

edit: here's the link:

https://www.diychatroom.com/threads/gfci-on-generator-tripping-home-backup.47903/



-ERD50

Quite right. My particular mfgr/model genny does not have a "kit" to do this. I did investigate it though. In order to disconnect the gen's earth connection I would have to go deep into the generator. There is no external gnd bond terminal. I have the knowledge to do it but chose to not do it. It is easier to just lift the gnd from the dedicated extension cable. That way the gen stays ready for stand alone service in addition to house backup duty.

 

[ERD50]

My house is wired like that too. I had a new panel installed when I moved into this house. It passed inspection at that time (about 5 years ago). However when the pool installer electrician came to do his run to the pool, he said that code is the separate the neutral from the ground. He basically said that my panel wasn’t done right. I told him to just install his run and not worry about it given that I had the inspection sign off right on the panel from less than 5 years ago at that time.

So, I don’t know what code is, but it might be that now you need separate ground from neutral.

Ground and Neutral should be tied together only at the main box, and then a connection from that to the earth ground rod.

If you have an additional box put in, I'm pretty sure (99.999% - may try to search later for refs) that you should have separate Ground, Neutral, and Hot going to that box. That maintains the integrity of keeping the Ground and Neutral tied together only at the point they connect to the ground rod.

-ERD50

 

[ERD50]

Quite right. My particular mfgr/model genny does not have a "kit" to do this. I did investigate it though. In order to disconnect the gen's earth connection I would have to go deep into the generator. There is no external gnd bond terminal. I have the knowledge to do it but chose to not do it. It is easier to just lift the gnd from the dedicated extension cable. That way the gen stays ready for stand alone service in addition to house backup duty.

But then, I think you need to have the generator connected to a ground rod for safety.

But if you do that, you'd probably trip again unless you disconnect your house from the ground rod.

-ERD50

 

[papaof2]

Only going by personal experience. We had power go out and when it came back on the fridge died. Repair guy hit us for $400...fried processor. Got a surge protector but it happened again anyway. With all the new electronics, I just wouldn't play around with switching around power sources. YMMV

I'd suggest buying a different brand of fridge ;-)

Our Samsung is happy on grid power, the less-than-perfect sine wave from an inexpensive generator or the very clean sine wave power from the inverter on the solar system. We have short power outages (under 4 hours) on a regular basis and the Samsung is still working after 4 years.

 

[gear2th]

Great discussion and lots of good ideas and things to think about.

The issue with turning off the main breaker is you won't know when the power is restored.

That's why I like to completely and totally isolate the power (H, N & G) from the generator and the circuits powered by it, from the service panel and the circuits powered by it.

I appreciate your advice and concern on using an electrician. The fact is I've never used an electrician for anything. I've completely installed brand new electrical service in dwellings starting from the weather head and service mast, down through the meter base, installed the service panel and wired all the circuits. Always passed inspection first time and usually complimented in the neatness of the job. All the electric company does is makes the service connection and plugs in the meter. The learning and satisfaction that comes from a DYI job well done, is hard to beat. Also a big factor in financial freedom.

After Superstorm Sandy in 2012, I had an electrician install a new service permitting manual switching between the main breaker and a generator input. He also installed a Reliance THP108 which serves as an alarm triggered when the power comes back on.

 

[OldShooter]

... serves as an alarm triggered when the power comes back on.

My two homes' manual transfer panel installations do not pick up every circuit in the house, so when the electric oven clock comes on I know that mains power has been restored.

 

[CRLLS]

Ground and Neutral should be tied together only at the main box, and then a connection from that to the earth ground rod.

If you have an additional box put in, I'm pretty sure (99.999% - may try to search later for refs) that you should have separate Ground, Neutral, and Hot going to that box. That maintains the integrity of keeping the Ground and Neutral tied together only at the point they connect to the ground rod.

-ERD50

This is the way I look at it: There is normally no need to ground rod the generator under stand alone use.

With the gen connected to the house wiring sans ground wire in the cable, the case of the gen is still protected from an internal fault and any external fault up to the plug connection a few inches from my service entrance via the gen's GFCI. Once power is fed into the breaker box (via conduit), the neutral wire is tied to earth gnd inside the box. Therefore all house equipment, including GFCI's work just as if the power company's source is there. It may not meet electrical code but should be just as safe.

I don't know how the NEC works, I have put several power supplies and UPS systems thru UL, CSA and TUV etc approvals. (although it was 20+ years ago) UL specifically says at the beginning of each spec something to the order of, if you meet this specification your supply still may not be safe and approved/listed, And if you do not meet this specification, it doesn't mean that it isn't safe or won't be approved/listed. Any questions, technical reasoning with the UL and CSA engineers prior to submission usually will get a determination of whether my system would be approved.