Aluminum wire for pump circuit?

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Odysseus99

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My pump will be 750' from the control box and generator. I planned to use #8 copper for a 1hp motor, which by the charts is good up to 950' for 1hp.

But I can get #6 aluminum a lot cheaper than #8 copper. #6 aluminum has the same ampacity as #8 copper.

Is there a consensus about using aluminum wire down the well, into the water? Advantages/disadvantages?

I thought about using #8 copper USE down the well (400'), then connecting at the well head to #6 aluminum XHHW from the well head to the control box (350'). Need special connectors to splice copper onto aluminum, but that's no big deal.

Anyone seen aluminum wire in a pump circuit after 30 years of service?
 

Valveman

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I never use copper down the well because of it's larger size and lack of flexibility. But it works OK underground. I would use #6 Aluminum underground and use 400' of #12 copper down the well. Using the longest length of the smallest wire possible actually makes a reduced voltage soft start of it's own. This doesn't slowly ramp up the speed, which is not good for the thrust bearing, but still reduces the stating torque.
 

Odysseus99

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I'm sure you meant ALU, Valveman.

That's a new one to me using the smallest wire possible for intentional voltage drop. #12 wire should easily handle the amperage of the motor while in continuous operation, with 1hp the amperage should be around 5 or 6 at 220 I guess. So you are saying that the voltage drop at startup when the amperage briefly spikes will reduce start torque and the problems it makes. But, would the lesser voltage drop occurring during normal run eventually mess with the motor, cause it to heat excessively?
 

Reach4

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Also note that conventional 2-wire pumps have less starting torque than 3-wire pumps do. I don't know by how much, but I see that as a feature.
 

Valveman

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= "odysseus99, post: 455986, member: 43819"]I'm sure you meant ALU, Valveman.

Yep Alu. Sorry guys, getting old. Here is what Franklin says about it.

Reduced-voltage starters may not be required if the maximum recommended cable length is used. With maximum recommended cable length there is a 5% voltage drop in the cable at running amps, resulting in about 20% reduction in starting current and about 36% reduction in starting torque compared to having rated voltage at the motor. This may be enough reduction in starting current so that reduced-voltage starters are not required.
 

DonL

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Yep Alu. Sorry guys, getting old. Here is what Franklin says about it.


Funny how people correct you when you are wrong, But do not correct you when you are right.

I did see that mistake, But knew better, and what you meant.

Have fun. I use copper when I can.
 
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