Wiring Size for Generator?

[SpiderDave]

Hey All!

I having a hiccup on a project, and hoping someone could help? I've contacted Generac, they won't advise. They referred me to a dealer and installers list, and they won't help either because of liability etc, etc.

I'm installing a Generac 14Kw Standby Generator. I do have a permit and doing it legit. The Transfer Switch beside the Service panel is about 147ft from the generator. All in conduit, and underground mostly. Inside the Transfer Switch Panel there are 6 terminals labeled T1, N1, N2, 0 Ground, 194 12v and 23 Transfer. The 6 wires that connect there also connect to the generator, and those terminals are labeled the same for an easy connection. Diagram / pic included.

Most of these I 'think' are sensor and internal monitoring system wires. One should be the trickle charge for the battery and likely powers the battery & oil pan heat pads as well. That's the one that concerns me the most. I can't find any specific info on them in the papers or manual that came with it.

Generac sells a wire kit by the foot for the 12kw - 16kw models. These 6 wires are listed as 18 awg stranded. But there is no info regarding distance or length limitations / recommendations on the wire. Depending on what it is, (providing the budget allows it) I like to bump up one gauge thicker than what's required on some projects. Especially when it's a long run of wire or I might put a greater demand on it later. But I'm not even sure what size wire to use here. I planned using 14awg, but a friend has raised a lot of questions that. I was hoping someone familiar with this could offer some insight or advice to get me back on track?

My concern is volt and amp drops over 147ft etc. Would 14/6 awg be fine? if not, what size do you recommend?

Thanks for reading and have a good one everybody!

 

[ez-duzit]

... 14/6 awg be fine? if not, what size do you recommend?

Thanks for reading and have a good one everybody!

That would be ridiculously small. Something more like 4 or 6-guage would seem more like it.

 

[Metal-Marc]

How many amps is the output breaker rated at?

 

[vhol5]

14g is more than enough, they're just signal wires.

 

[mm08822]

That would be ridiculously small. Something more like 4 or 6-guage would seem more like it.

He's talking about signal not power wiring.

 

[mm08822]

I always run 14 copper for the control lines and never a problem.
N1, N2 are the utility sense lines. T1 is the charger.

Throw away the battery heating pad. Otherwise you will be buying a battery in 2 years.

Now I only use the oil filter heater.

For power, run 2 - #3, 1 - #4, 1 - #6 grn Alum XHHW. If you can't find #3, use #2.
I hope you have run 1-1/4" conduit for the power.

 

[SpiderDave]

How many amps is the output breaker rated at?

I always run 14 copper for the control lines and never a problem.
N1, N2 are the utility sense lines. T1 is the charger.

Throw away the battery heating pad. Otherwise you will be buying a battery in 2 years.

Now I only use the oil filter heater.

For power, run 2 - #3, 1 - #4, 1 - #6 grn Alum XHHW. If you can't find #3, use #2.
I hope you have run 1-1/4" conduit for the power.

Sorry for the slow reply, work called me in and got in the way.

@Mtl-Marc, rated at 200amps if your talking about the transfer switch? (whole house generator) 200 amps also at the house main panel too.

I used 4ga on the pwr and neutral, 6awg on the ground inside of 1 1/2" conduit along side of 3/4" for the service wires, joined at a junction box where it meets under the house. From there I bumped it up to 2" the rest of the way to the Transfer Switch. From the Service Panel to Transfer Switch it's very short being side by side, but I'm using 3" conduit with SER wire, keeping all that 2-2-2-4. The Transfer Switch Panel is rated at 200amp, Generator's 14kw, 60 amp output.

Also put a junction / breaker box with breaker, on a pole next to the generator to bring it all together. From that box to generator, I plan on using 2" liquid-tight flex conduit to absorb any vibration or pad heaving during winter freezes.

@mm08822 I used 4ga after being told by electricians that 6ga would do fine. And Generac sells their kits by the foot for the 16kw generators with 4ga. wire. So I went with 4ga for my 14kw generator. Is that going to be a problem you think? It's my understanding 4ga handles 85 amps, 16320 watts and I was told that wire is rated for 300ft. Is that not correct?

BTW, thanks for the warning on the heating pad! I read some where a while back that they were worthless becasue they didn't last long, but not about them ruining the battery like that. Jeez. I'm curious, what causes the short life on the battery like that?

Sounds like 14ga is what I'm going to use for the service wires. Thank you all for that!.

 

[TurnipTruck]

I also just installed an 18kw Generac about 75 feet from the transfer switch. I ran #4 in 1” and #14 control/signal wires in another 1”. I later added the low temperature kit early in the winter. I may unplug the battery warmer for the summer, but I will keep the oil filter warmer connected.

Cat helped pull wires:


Without the heaters, I don’t think I could find the generator half the time:

 

[mm08822]

Sorry for the slow reply, work called me in and got in the way.

@Mtl-Marc, rated at 200amps if your talking about the transfer switch? (whole house generator) 200 amps also at the house main panel too.

I used 4ga on the pwr and neutral, 6awg on the ground inside of 1 1/2" conduit along side of 3/4" for the service wires, joined at a junction box where it meets under the house. From there I bumped it up to 2" the rest of the way to the Transfer Switch. From the Service Panel to Transfer Switch it's very short being side by side, but I'm using 3" conduit with SER wire, keeping all that 2-2-2-4. The Transfer Switch Panel is rated at 200amp, Generator's 14kw, 60 amp output.

Also put a junction / breaker box with breaker, on a pole next to the generator to bring it all together. From that box to generator, I plan on using 2" liquid-tight flex conduit to absorb any vibration or pad heaving during winter freezes.

@mm08822 I used 4ga after being told by electricians that 6ga would do fine. And Generac sells their kits by the foot for the 16kw generators with 4ga. wire. So I went with 4ga for my 14kw generator. Is that going to be a problem you think? It's my understanding 4ga handles 85 amps, 16320 watts and I was told that wire is rated for 300ft. Is that not correct?

BTW, thanks for the warning on the heating pad! I read some where a while back that they were worthless becasue they didn't last long, but not about them ruining the battery like that. Jeez. I'm curious, what causes the short life on the battery like that?

Sounds like 14ga is what I'm going to use for the service wires. Thank you all for that!.

If it was #4 Copper then that is ok, just more $$.

2-2-2-4 between the transfer switch and old main panel (now sub panel needs to be rated for 200A. I hope you meant 2/0 copper and not #2.

When the voltage drop is considered and limited to less than 3%, 300' is actually more like 150' for #4 Copper @85A. You are fine at 60A/150' if copper.

The battery heating pad stays on too long and at too high of a temp for my area. It will boil off the electrolyte with that excessive heat applied at the bottom of the battery base. Many have seen this problem, learned the hard way.
If your winters are really low temps, you may want to consider a 2 pole switch to turn it off from April - Nov or there abouts.

 

[mm08822]

I also just installed an 18kw Generac about 75 feet from the transfer switch. I ran #4 in 1” and #14 control/signal wires in another 1”. I later added the low temperature kit early in the winter. I may unplug the battery warmer for the summer, but I will keep the oil filter warmer connected.

Cat helped pull wires:


Without the heaters, I don’t think I could find the generator half the time:

If #4 Copper, then is good.

Did the cat run off with the ground wire to the gen?

Being in Alaska, you probably have a need in the winter for heater. I still suggest you disconnect it for the warmer temps.

 

[TurnipTruck]

If #4 Copper, then is good.

Did the cat run off with the ground wire to the gen?

Being in Alaska, you probably have a need in the winter for heater. I still suggest you disconnect it for the warmer temps.

Had to use copper to fit the 1” conduit.

The cat helped to pull the ground with the sense wires in the other conduit, couldn’t fit it all in one.

 

[mm08822]

Had to use copper to fit the 1” conduit.

The cat helped to pull the ground with the sense wires in the other conduit, couldn’t fit it all in one.

Tell the cat, next time all conductors for a circuit need to be in the same conduit, in this case the power circuit.

 

[SpiderDave]

I also just installed an 18kw Generac about 75 feet from the transfer switch. I ran #4 in 1” and #14 control/signal wires in another 1”. I later added the low temperature kit early in the winter. I may unplug the battery warmer for the summer, but I will keep the oil filter warmer connected.

Cat helped pull wires:


Without the heaters, I don’t think I could find the generator half the time

If it was #4 Copper then that is ok, just more $$.

2-2-2-4 between the transfer switch and old main panel (now sub panel needs to be rated for 200A. I hope you meant 2/0 copper and not #2.

When the voltage drop is considered and limited to less than 3%, 300' is actually more like 150' for #4 Copper @85A. You are fine at 60A/150' if copper.

The battery heating pad stays on too long and at too high of a temp for my area. It will boil off the electrolyte with that excessive heat applied at the bottom of the battery base. Many have seen this problem, learned the hard way.
If your winters are really low temps, you may want to consider a 2 pole switch to turn it off from April - Nov or there abouts.

@TunripTruck that's a very handy cat! My dog never helps, just stands arounds criticizing. Jeez, you got a little bit on snow I guess. Ha ha! Thanks! Nice set up you go there.

@mm08822 Yes, it's all cooper except the Aluminum SER wire. And your right, I forgot to say 2/0 not 2 awg. Thanks for lookin' out for me there. Dang, that battery warner sounds like a pain. We do get some bad winters once in a while, so a switch is great idea for the rare times I'll actually need it. I may even put something between the pad and the battery to buffer that heat. Or just avoid it all together.

One last question mm08822,.. if I may? You mentioned all conductors for a circuit have to be inside the same conduit? Does this apply to the 6 @ 14awg sensor wires also? They're not considered part of the circuit, are they? Can I go ahead and run those inside the 3/4" conduit that runs along side of the main 1 1/2" conduit? Or does it need to be all in one? I'm hoping to run it today or tomorrow, so I just want to do it right.

Everybody, I really appreciate all of your time, responses and info.

 

[wyliesdiesels]

The control circuits can be in their own conduit. Its just that ALL of the control conductors need to be in the same conduit...

 

[mm08822]

I run all power conductors in 1-1/4" conduit = 2 hots, 1 neut, 1 grd
And
I run all control conductors in a separate 3/4" conduit = 6 #14 thwn

 

[SpiderDave]

I run all power conductors in 1-1/4" conduit = 2 hots, 1 neut, 1 grd
And
I run all control conductors in a separate 3/4" conduit = 6 #14 thwn

Perfect, thank you!

 

[mm08822]

@TunripTruck that's a very handy cat! My dog never helps, just stands arounds criticizing. Jeez, you got a little bit on snow I guess. Ha ha! Thanks! Nice set up you go there.

@mm08822 Yes, it's all cooper except the Aluminum SER wire. And your right, I forgot to say 2/0 not 2 awg. Thanks for lookin' out for me there. Dang, that battery warner sounds like a pain. We do get some bad winters once in a while, so a switch is great idea for the rare times I'll actually need it. I may even put something between the pad and the battery to buffer that heat. Or just avoid it all together.

One last question mm08822,.. if I may? You mentioned all conductors for a circuit have to be inside the same conduit? Does this apply to the 6 @ 14awg sensor wires also? They're not considered part of the circuit, are they? Can I go ahead and run those inside the 3/4" conduit that runs along side of the main 1 1/2" conduit? Or does it need to be all in one? I'm hoping to run it today or tomorrow, so I just want to do it right.

Everybody, I really appreciate all of your time, responses and info.

So if it is 2/0 Alum and not 2/0 copper, then those conductors are too small for 200A. You need 4/0 Alum (technically 250mcm, but I've never had a problem using 4/0 Al with the inspector when the new xfer switch is right next to sub-panel (old main panel.) You don't need SER either.

Do you remove the bonding screw from the neutral bar in the old main panel?
Are the grd wires removed from the (isolated) neutral bar in the old main panel?
Did you bond the neutral in the grd bar in the xfer switch?
Did you move the grounding electrode conductor from old main panel into new xfer switch?
Did you move any bonding jumpers from water and gas piping from old main panel into new xfer switch?