bamaboy473

...for the month


The electrician that will do the final hookups told me to source cable for a 65A circuit breaker on our Generac 16Kw whole-house generator. I'm getting conflicting information on the internet, and around town. Here's hoping that a THT concensus will get the job done:

Total run is about 70' to the transfer switch from the genset. Install will be in PVC because it will go above and below ground.

? What size cable is correct?
? Any preference of copper over aluminum?

This is a Generac 16Kw with a 65A circuit breaker. My part of the job will be pulling and installing the cable, ready for him to inspect and connect to the main panel.

?Will connection from transfer switch to the main panel (about a 3' run) be the same size cable, or larger?

ladyjane

Transfer switch and 100 amp min.

Mine Now

No aluminum

bamaboy473

They sure sell alot of it, but if copper is best, what size to use? 6?

bamaboy473

What I need to know is the size of cable that will run from the genset to the transfer switch. Any idea?

If the breaker is 65A for 220V, are you suggesting that the cable needs to support 100A?

ladyjane

I have run 2/0 for that under 8 5 feet for 100 service you can google nation electric code for a chart

houtxfisher

Why not?

Crabpot Man

AL 2 gauge, COP 4 gauge. Nothing wrong with AL if properly installed, that is what your service entrance is.

HTV

For 65 amps #6 should be fine. But if the transfer switch is rated for 100 amp you may have to bump it up #2 and maybe #4 for the neutral to meet some code requirement. I have a 20kw which I think has an 85 amp breaker and used #4, but only had to run about 20 feet, and no problems going on 3 years.

Mine Now

Supposedly it expands and contracts more then copper wire, which in time causes loose connections.

NFG

#6 THWN copper is rated for 65 amps in the 75 degree column of table 310-15. THWN is the type of insulation on the conductor. If you use the romex type of cable the insulation is a different type and not rated for 65 amps.( that may have changed by now?)

NFG

At panel put a 65 amp breaker. From that breaker run (3) # 6 and (1) #8 ground to transfer switch. from transfer switch run same wire to generator.. What type of transfer switch do you have? Is it the type that is also a load center? You will also need control wires. 4 or 6 depending on type and age of generator.

forgot

That was in the old days. Different alloys used now. But a little Noalox for corrosion isn't a bad idea.

bamaboy473

The main panel has a 100A breaker (along with several other breakers from 40 to 100A for heat, a/c, WH)

Generac RTS switch will be mounted next to/close to the main panel, so runs from main breaker to switch and back will be very small; less than 2'. The feed run from genset to switch is the long run, and your suggestion is the same as one of the supply houses for copper, so that's comforting

The electrician has installed these before, but hasn't physically looked at mine, which is why he couldn't give exact specs because I didn't know distance at that time.

FWIW, is there a huge price bump going from aluminum to copper? For what little I need, it should be nickles and dimes, shouldn't it?

Crabpot Man

At 70' DO NOT run #6, you WILL regret it.

I speak from first hand experience.

forgot

# 2 URD, [3 #2 Aluminum Conductors] should run around 1.25 ft.
# 2 Copper THHN, [1 #2 conductor, you need three] should run around 1.35 ft. [3x1.35]
Just an example.

NFG

There will be little to no voltage drop at 70 feet.

NFG

Your panel has a 100 amp main breaker? What kind of transfer switch do you have?

forgot

The Generac RTS series is the automatic transfer switch mention.

NFG

Is the transfer switch strictly a transfer switch or is it also a load center?