Do it Yourself: Re: [DIY] 3rd Power Line on Duplex

22 May 2015

Re: [DIY] 3rd Power Line on Duplex

Taking this idea further...
This is assuming you only use 120VAC for your laundry room.
Looking for transformers, a common transformer is a single phase 480/240V on the high side to 240/120V on the low side. A 2:1 winding.
If 240V is applied across the high side, 120V will be the output on the low side. It won't be referenced to ground however.
Feeding power to the high side from a 15A breaker from each breaker box should give a potential of 15A of 240 at the high side of the transformer.
The low side would need to be fed to its own breaker or fuse box. It should be able to easily handle 20A to one outlet branch.
If the 240V side is fed 15A of 240V, the kVA rating needs to be at least 3000 or 3kVA. Using 3kVA as a power rating, the 120V side should support 25A. The next common size of transformer is 5kVA and a lot more expensive.
But probably not legal as its extended across two services. But it would likely work for most of your points of concern.
This transformer is a 3kVA. High side would use about 12.5A, low side should support 25A at 120V.
calculations are:
3000 kVA / 240V =12.5A (high side)
3000 kVA / 120V =25A (low side)
http://www.grainger.com/product/DAYTON-Transformer-31YD59?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/31YD59_AS01?$smthumb$

Just my thoughts as crazy as they might be,
Steve

On 5/21/2015 9:20 AM, Steve Wilson virtualwilz@yahoo.com [DoIt_Yourself] wrote:

This may be crazy but...
Was thinking of an isolation transformer.
Take one phase from one apartment, the other from the other apartment to feed the input side of the transformer. Transformer would have to be for 240V and capable of handling 20 to 40 amps depending on how many circuits you need.
The output side should give a balanced load from both apartments. Each phase on the output would still be 120V to ground so long as the transformer is a 1:1 design.
The ordeal would be finding a suitable and affordable transformer for the task.
But that wouldn't solve the issue of one apartment loosing power, either apartment looses power, power would be out for the transformer.
Probably not legal but may work in theory.
Steve

Does anyone know a way to feed the electricity from both sides in such a way that if both sides are turned on, the electricity is equally shared, but if either side is shut off at the meter, the electricity automatically shifts to the other side?

Sounds like an exciting project, eh?