one load to get power from 2 sources

[kosbo]

Hi All,
Does anyone know any special device, which allows to supply equally power from 2 sources to one load? Two houses connected to one sewage septic tank, where air pump has to be connected to mains. Because of two houses have to share it, I need to find something which would equally spread this load between 2 houses supplies. I can use 2 timers, but may be somebody knows about any special device for this purpose ?

Thanks in advance, Constantine

 

[kosbo]

I have to switch all 3 wires - live, neutral and earth too, as it's from 2 different supplies and I do not want to combine earths and/or neutrals, so I need controlled changeover switch or relays...

 

[Knobhead]

Switch the earth?

Think you had better employ a qualified electrician.

 

[Adam W]

... if one house supply is completely switched off for some reason ( nobody leaves there, went on long holidays and so on) sewage air pump would be still alive (50% time of cause).

Or if one or even both customers don't fancy paying their share any more and turn the breaker off.

 

[Sintra]

If both supplies were permanently live then all you need is a 4 pole contactor with a pair of NO and a pair of NC contacts. Supply the coil of this via a time clock set to switch daily. Just don't switch the earth lol

 

[kosbo]

thanks a lot, it's all clear now.

 

[Knobhead]

Stop looking for the complicated and dangerous solution!

This isn’t an electrical problem, it’s a legal problem.

It’s quite easy for the solicitors to draw up a common services agreement. No different to the landlords supply in a block of privately owned flats, if you don’t sign the contract you can’t buy the place.

A simple shared service meter is the best option, if needs be a separate DNO supply.

Yes I’ve worked on shared supplies, on an industrial scale.
The lawyers and accountants had a field day! Operational wise it was a nightmare!

 

[Knobhead]

If both supplies were permanently live then all you need is a 4 pole contactor with a pair of NO and a pair of NC contacts. Supply the coil of this via a time clock set to switch daily. Just don't switch the earth lol

But who pays for the control supply?

This whole idea of a shared/dual supply is stupid and fraught with danger!

 

[kosbo]

why do you think this is dangerous solution?

 

[Sintra]

But who pays for the control supply?

This whole idea of a shared/dual supply is stupid and fraught with danger!

Lol not agreeing with the set up the op has proposed just showing how simple it is electrically to do.

 

[Knobhead]

why do you think this is dangerous solution?

Just sit down and think about it!

 

[ahtyrrell]

Those treatment plants use about 50 watts of power so worked out over a year at 14p per kwh that's about £60 its a known demand and should be easy to calculate the cost, so not even worth the cost of a meter in reality the electricity is a very small amount of the over all running cost for two properties it needs emptying every 6 months to a year at over £200 a pop so if they can't agree to a shared elec cost then god knows how they would handle a blockage or break down efficiently whitch can be expensive I would put the supply for the tank on a separate small consumer unit in one house though so the house can be isolated without the tank supply being effected

 

[kosbo]

Just sit down and think about it!

I sat down and thought about it and can not see anything dangerous there, more details of danger in this circuit please?

 

[kosbo]

I am not against of just connecting it to one house and it's simple and easy for me too, but cannot understand what's is wrong with shared/dual supply idea and why it's dangerous...

 

[trev]

why do you think this is dangerous solution?

Are you kidding us?

 

[trev]

I am not against of just connecting it to one house and it's simple and easy for me too, but cannot understand what's is wrong with shared/dual supply idea and why it's dangerous...

Two houses on separate phases, over time the labelling gets misplaced or defaced, guy comes along to work on it, both householders are out, he isolates from the one house he has access to and commences work, midway through timeclock thinks oooo it's time to switch the supply...
I'll leave you to imagine the rest.