[RE-wrenches] Autoformer and long AC run

[drake.chamberlin at redwoodalliance.org]

Hi Brad, 

The auto transformer should work just fine. You should get 4X the
efficiency with 1/2 the current and twice the Watts / Volt. I don't know
how much benefit is available from paralleling wires of different sizes;
it is not recommended practice of course. 

If you find a source for those old auto transformers, I'd sure like to
know. 

Best, 

Drake 

Drake Chamberlin 

Athens Electric LLC 

Ohio Electrical Contractor's License 44810 

CO Master Electrician's License 4526 

NABCEP Certified PV Installation Professional

---

On 2021-08-02 15:16, Bradley Bassett wrote:

> The system currently has a 600 foot run of 2-2-4 aluminum from the service to the house loads. The load is often only 120VAC which gives a large voltage drop using only the #2 and #4 conductors. My thought was to install an autotransformer at the load end so that the current runs through the #2 conductors at 240VAC for much less voltage drop. Are there any issues I should be looking at doing this? I'm thinking that to balance the legs a 4kVA autoformer would be adequate. The circuit is protected by 30A breakers both ends. 
> 
> Second question is if I could reduce the voltage drop even more by taking the #4 and paralleling it to one of the #2 conductors. This would eliminate the neutral on the long run. I'm thinking that the autoformer could generate a new neutral for the load circuits. This is an older install so the neutral is already grounded to earth at both ends, there is no ground wire between the two such as would be required by code now. I know that code does not allow paralleling conductors smaller than 1/0 but I will disregard that in this case since it's my own system. 
> 
> If anyone has one of the old AEE toroid autoformers you'd like to sell, or if you want one yourself we can do a bulk buy. Let me know off list. 
> 
> Thanks, 
> 
> Brad Bassett 
> 
> AEE Solar 
> 
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