bones1
I have a 5449 panel installed and haven't purchased a generator yet. I was trying to get the wire run ahead of time before I order one. For the 20KW model my electrician says either #4 copper or SER2224. I am confused as what to buy for the aluminum choice which I prefe$. Ser2224 is #2 wire, there is also SER1113 but then the awg2 came up and lost me.
Gen puts out 83.3 amps, wire goes to 125A breaker in panel. Thanks.
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Skip Douglas SkipD
Why would you want to go with aluminum wire over copper?
Skip Douglas
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bones1
You know, I haven't priced 300ft of copper wire yet just going by what folks tell me as to price.
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Skip Douglas SkipD
If you're going to run a 300-foot cable, you should probably look at voltage drop calculations. You may need to up the size of the wire accordingly. I can't find what I was looking for in the NEC, but maybe one of the electricians here can help.

One problem I have with aluminum wire is the required larger size and the potential difficulty in routing and terminating it because of the size. I think space would have been an issue inside my generator if we'd used aluminum feeder wiring.
Skip Douglas
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bones1
Thanks. Four 75 ft runs of #4 copper vs one run of SER2224(if it is big enough) to the panel in the garage.I will terminate at an outdoor box near the generator then from the box to the generator with #4 copper. The SEC2224 aluminum runs me $1.42 a foot,I have not priced the copper as I didn't think I would use it.
Am I thinking right?.
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Skip Douglas SkipD
bones1;12278 wrote:
Thanks. Four 75 ft runs of #4 copper vs one run of SER2224(if it is big enough) to the panel in the garage.I will terminate at an outdoor box near the generator then from the box to the generator with #4 copper. The SEC2224 aluminum runs me $1.42 a foot,I have not priced the copper as I didn't think I would use it.
Am I thinking right?.
If one of the four wires is for equipment ground, you can save right there. You don't need a #4 for that. You can use a smaller size for that, but I can't quote the size right now.
Skip Douglas
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ceb58
bones1;12271 wrote:
I have a 5449 panel installed and haven't purchased a generator yet. I was trying to get the wire run ahead of time before I order one. For the 20KW model my electrician says either #4 copper or SER2224. I am confused as what to buy for the aluminum choice which I prefe$. Ser2224 is #2 wire, there is also SER1113 but then the awg2 came up and lost me.
Gen puts out 83.3 amps, wire goes to 125A breaker in panel. Thanks.


I hate to be the bearer of bad news,well not really but........ Your electrician needs to look at 240.4 (2008) Your wire must be sized to the over current protection which would be the 125 amp breaker. So you would need 1/0 Al SER or #1Cu THWN.
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bones1
Here we go again. Anyone familiar with the 5449 Generac panel with the transfer switch built in?. They refer to all the breakers in this unit as "breakers"which is what they are but when they get to the 125A one where the wire in question connects from the generator it is referred to as a switch?.Is it different from a breaker?. I don't want to buy wire so large that it won't fit in the lugs on the breaker. Does anyone know what size breaker is on the 20KW generator,I don't have it yet?.
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genme
bones1;12290 wrote:
Does anyone know what size breaker is on the 20KW generator,I don't have it yet?.
Our 5875 20kW model rated at 83.3 amps came with a 100 amp breaker on the side panel.
Model 5875, Nexus controller, 999cc Engine, 20kW LP, 2011
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bones1
Which one do I go by?. The 125A in the panel or the 100A on the generator when sizing wire?.
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ceb58
bones1;12290 wrote:
Here we go again. Anyone familiar with the 5449 Generac panel with the transfer switch built in?. They refer to all the breakers in this unit as "breakers"which is what they are but when they get to the 125A one where the wire in question connects from the generator it is referred to as a switch?.Is it different from a breaker?. I don't want to buy wire so large that it won't fit in the lugs on the breaker. Does anyone know what size breaker is on the 20KW generator,I don't have it yet?.


OK, after looking at this panel I see what it is. A split buss panel dressed up. The 125 amp breakers,and yes they are breakers, are for the utility side and generator side.
Now a 20Kw generator will have a 100 amp breaker on it
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GENERATOR
Model 005875-0 (20 kW)
Rated Maximum Continuous Power Capacity (LP)
20,000 Watts*
Rated Maximum Continuous Power Capacity (NG)
18,000 Watts*
Rated Voltage
240
Rated Maximum Continuous Load Current – 240 Volts
83.3 LP
Main Line Circuit Breaker
100 Amp

This is where the wire will be sized to the OCP. The 125 amp breaker in the panel will now be no more than a disconnect.
So your wire will have to be #1/0 Al SER or #3 Cu THWN
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Astro
The generator will only put out 83 amps. You look up the 83 amps then base the wire size on the distance from the panel to the geneator. Stranded copper will be a smaller size than aluminum because copper conducts better.

The panel is rated at 125 amps that the total safe load you can pull at one time while hooked to the power company or if you had a larger generator.

Hope this helps
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Skip Douglas SkipD
Astro;12297 wrote:
The generator will only put out 83 amps. You look up the 83 amps then base the wire size on the distance from the panel to the geneator. Stranded copper will be a smaller size than aluminum because copper conducts better.

The panel is rated at 125 amps that the total safe load you can pull at one time while hooked to the power company or if you had a larger generator.

Hope this helps
The above is not correct.

Here's a quote from the 2008 NEC with my point in bold type:

445.13 Ampacity of Conductors.
The ampacity of the conductors from the generator terminals to the first distribution device(s) containing overcurrent protection [B]shall not be less than 115 percent of the nameplate current rating of the generator[/B].
Skip Douglas
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ceb58
Astro;12297 wrote:
The generator will only put out 83 amps. You look up the 83 amps then base the wire size on the distance from the panel to the geneator. Stranded copper will be a smaller size than aluminum because copper conducts better.

The panel is rated at 125 amps that the total safe load you can pull at one time while hooked to the power company or if you had a larger generator.

Hope this helps


You need to stop because you do not have a clue.
Once again. The 20Kw will have a 100amp breaker. This is what the wire will be sized to 240.4 (2008) NEC.
The wire size will come from table 310.16 (2008) NEC
So for 100amp it would be #1/0 Al SER from the 60 deg. column or #3 Cu THWN from the 75 deg. column.
As far as distance that is a calculation that must be done with wire size and type, amp load and voltage to determine voltage drop and if the wire must be up sized.
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ceb58
SkipD;12299 wrote:
The above is not correct.

Here's a quote from the 2008 NEC with my point in bold type:

445.13 Ampacity of Conductors.
The ampacity of the conductors from the generator terminals to the first distribution device(s) containing overcurrent protection [B]shall not be less than 115 percent of the nameplate current rating of the generator[/B].


Skipp, that code is for generators that do not have over current devices built in, which is hard to find now. So if the generator has the breaker on it this code is moot.
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bones1
Thanks guys for all your help. 1/0 Al SER it is then for a 75 ft run outside to a box. From the box to the generator #3.
Thanks again for the help.
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Skip Douglas SkipD
ceb58;12301 wrote:
Skipp, that code is for generators that do not have over current devices built in, which is hard to find now. So if the generator has the breaker on it this code is moot.
Thanks for that tidbit.
Skip Douglas
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Astro
You know that the 14kw unit has only a 60 amp breaker and it max load is 58.3 amps. Why would a 83.3 amp out put on a 20kw be breakered at 100 amps ? Did generac cheat me. I work in the electronics field on million dollar pieces of equipment, Wire size and breakers or fuses are always set by current draw, voltage and distance. I do have a clue.

The way I read the post the guy's did not under stand how his boxed worked and what wire size to use. He was trying to save money by using aluminum wire which is not the best choice.

CEB58 maybe you don't have a clue, oh that's right you just have a book to read out of.
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ceb58
Astro;12306 wrote:
You know that the 14kw unit has only a 60 amp breaker and it max load is 58.3 amps. Why would a 83.3 amp out put on a 20kw be breakered at 100 amps ? Did generac cheat me. I work in the electronics field on million dollar pieces of equipment, Wire size and breakers or fuses are always set by current draw, voltage and distance. I do have a clue.

The way I read the post the guy's did not under stand how his boxed worked and what wire size to use. He was trying to save money by using aluminum wire which is not the best choice.

CEB58 maybe you don't have a clue, oh that's right you just have a book to read out of.


Yea, 30 years pulling wire, my own electrical contracting business and a book that's all I got.
OH, by the way Generac used 240.4 (B)(2) on you.
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Canada_Guy
I'm curious about reduced neutrals. Are they allowed for the generator feed?

In my area (British Columbia), they allow reduced neutrals for utility service feeders. We are allowed to run #8 for 60-amp services and #6 for up to 200 amp services.
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ceb58
Canada_Guy;12316 wrote:
I'm curious about reduced neutrals. Are they allowed for the generator feed?

In my area (British Columbia), they allow reduced neutrals for utility service feeders. We are allowed to run #8 for 60-amp services and #6 for up to 200 amp services.


Are you sure that's not the equipment grounding conductor? A #6 neutral on a 200amp feeder is a little small.
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Canada_Guy
ceb58;12318 wrote:
Are you sure that's not the equipment grounding conductor? A #6 neutral on a 200amp feeder is a little small.


I confirmed it is the neutral and it was adopted in the 20th edition of the Canadian Electrical Code (the 21st is now out and it's the same) Rule 4-022 and 10-204.

Both the neutral and ground conductor are allowed to be #6 copper (not sure if it needs to be up sized for aluminum conductor) on up to a 200 amp service.

The reasoning is that the neutral only carries un-balanced load and most high current loads are all 240 volt (ranges, hot water heaters, space heating, electric furnaces).

I was curious if the US had a similar allowance.
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ceb58
Canada_Guy;12327 wrote:
I confirmed it is the neutral and it was adopted in the 20th edition of the Canadian Electrical Code (the 21st is now out and it's the same) Rule 4-022 and 10-204.

Both the neutral and ground conductor are allowed to be #6 copper (not sure if it needs to be up sized for aluminum conductor) on up to a 200 amp service.

The reasoning is that the neutral only carries un-balanced load and most high current loads are all 240 volt (ranges, hot water heaters, space heating, electric furnaces).

I was curious if the US had a similar allowance.


OK,to answer your question yes the NEC dose have provisions for reducing the size of the grounded conductor (neutral) 220.61 A,B&C. But there are so many hoops to jump through and calculations for the majority of the time it is not worth it. Also SE and SER come as a cable assembly and the neutral is sized along with the ungrounded (hot) conductors.
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