2 power sources to one water pump

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  #1  
Old 06-15-16, 04:34 PM
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2 power sources to one water pump

Hey all,
I am trying to figure out a solution to a wiring problem i am having with my apartment in Egypt while I am traveling. There is a water pump in the building to increase the water pressure. However the pump is wired to be turned on by either my apartment or the apartment below me. Currently there is just a light they comes on to let me know if they have their switch on.. so i don't turn mine on.
However i want to make it so that both switches can be turned on at the same time, so that if i am showering and they turn their switch off the pump doesn't stop.. it will only stop if both switches are off.. but won't overload the pump if both are on. I believe I would use something like a relay but i am not sure.. I attached a rudimentary diagram of what i am talking about.

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  #2  
Old 06-15-16, 07:19 PM
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Welcome to the forums!

The first issue is that you are renting and do not own the property. In the US you would not legally be able to modify the current installation. Doing so could put you at risk if anything were to go wrong.

Speaking hypothetically there are options to do what you propose. If your switch and their switch are on the same circuit you could just parallel the two switches.

Depending on your wiring method you could add/change the wires to parallel the switches.

There is also likely a relay option.
 
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Old 06-15-16, 10:06 PM
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It would be extremely challenging to do what you want if there are separate feeds to that pump from two different electric panels.

I take it that it's your apartment.... is that correct ?
If it's an apartment building.... the pump should technically be on a house panel. Then it would be easy to wire two switches.
 
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Old 06-16-16, 10:56 AM
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What happens if both switches are turned on right now?

Is the pump strong enough for both apartments to be using it at the same time? If not then stop here; do not investigate any wiring changes. The indicator light is supposed to tell you that you should not be using the water.

*******************

You can make a legitimate connection with no relays so both switches can be on at the same time.

Run another cable from the pump room junction box to your switch box.

In the pump room junction box reconnect the pump cable only to your original cable.
In the pump room junction box connect the other apartment original cable to the new cable.

At your switch box connect a double pole double throw switch in place of the existing switch.

The middle terminals of the DPDT switch connect to the original cable down to the pump junction.
The new cable goes to one pair of side terminals of the DPDT switch.
Your power goes to the other pair of side terminals of the DPDT switch.

No changes at the other apartment switch box. It should have a double pole single throw switch for hot and neutral but if it does not then leave it as is anyway.

In the diagram some ground wire are not shown because the diagram is too crowded for them. Ground wires accompany all pairs of hot/neutral lines in the respective cables.

How it works: When your switch is in one position (you label that position as "on"), it supplies power to the pump and the other apartment switch does nothing. When your switch is in the other position then your power is removed from the pump and the other apartment can send its power to the pump via your switch. Indicator lights are not needed.
 
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Last edited by AllanJ; 06-16-16 at 11:25 AM.
  #5  
Old 06-16-16, 12:28 PM
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Is the neutal shared? I'm assuming so based on your drawing. I'm not sure why this wouldn't work as is with both switches open.

The best option although a bit more expensive would be to install a pressure switch in the plumbing so that the pump reacted automatically to demand. Lots of pressurizing pumps come with a control like that preinstalled but it shouldnt be hard to find a stand alone option.
 
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Old 06-16-16, 12:51 PM
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Is this a booster pump to increase water pressure from the city water?

If so, I don't understand why they used switches in the first place. Booster pump should be wired to a pressure switch (often they have one built in) and kick on when the pressure drops below set pressure and shuts off when the pressure increases above set pressure.
That way, when ever water is turned on, pump kicks on.

Running a pump without pressure switch can be dangerous as pressure in the pipe will increase to the maximum pressure the pump is capable unless the pump is turned off immediately after turning the faucet off.
Otherwise, it can damage plumbing and the pump.
 
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Old 06-16-16, 01:09 PM
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Until (if?) curiousone returns we can only speculate. I'm wondering if the green box with the question marks is existing or is what curious is suggesting.

Here is what I suspect. The green box DOES exist and it has relays in it that are controlled from the apartments. The relay power contacts close to the "house" power and energize the pump when either or both of the apartment switches are closed. Since it is two pilot devices it would not matter if both were closed at the same time.

This arrangement would allow for the landlord to be paying the cost of the pump operation, not have the pump running when not needed and not have to depend upon a pressure switch that could cause the pump to run intermittently due to leakage from the piping. Of course there is nothing to keep the tenant from simply leaving the control switch in the on position at all times unless the control is a timer.

At any rate, my personal opinion is that this pump and control belongs to the building and/or landlord and as a tenant curiousone has no legitimate reason for futzing with it. If he/she has a problem with the pump he/she has to notify the management of the building of the problem.
 
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Old 06-16-16, 11:09 PM
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Hey guys thanks for the replies.

So the situation is that we own the apartment.. but the way things work in Egypt is nothing like that back in the states or in an civilized country lol.. So basically the pump is shared between the 6th and the 7th floor because there is very little water pressure for the public mains..

The pump itself has a pressure switch and will turn on and off however the problem is as Furd mentioned there is a leak in a pipe that is nearly impossible to reach due to an illegal building next to us and illegal modifications in our building, so the pump would run nearly all the time.. and since the way it works here in Egypt both apartments are responsible for the pump and replacing it if it breaks and maintaining it. The building owners build and then sell the apartments and really only retain part of the rights to the land the rest is for the apt owners. In addition the pump itself is strong enough to be used be at the same time by both apartments.

As far as the wiring goes right now if you turn both switches on the one that is turned on second will blow a fuse which leads me to believe that the wiring is too independent circuits or even from the different apartments. And there is no pump room they just attach the pump to the wall with some metal anchors and run electricity to it from where ever they can when they installed it.. most of the things done here are not done correctly or in a way that makes sense logically.. so don't give yourselves a headache trying to figure out why they did something that doesn't make sense.

In the diagram I should the green box does not exist I was merely asking about what should that green box be.. I know its possible to set it up so if one switch is on the other will basically be redundant until the 1st switch is turned off.. when I asked the electrician he said its not possible (but again take this with a grain of salt.. they don't like to do more work then they have too and are many times ignorant of the proper way or the possible ways)...

I think I will go with the solution of the using one power source coming from one of my breakers and putting parallel switches as I believe it allows for the "redundant switch".. if someone could explain it a little further i would appreciate it though
 
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Old 06-16-16, 11:18 PM
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Thanks for the reply AllanJ as I said in my general reply the pump is strong enough for both apartments to use the water at the same time. However i looked at your diagram and explanation and I just want to clarify something.. if I do it this way by putting DPTP switch in my apartment and connecting the apartments switch below to it.. We can't both have the switches "On" correct? if mine is in the up position his will have to be in the down? and if switch mine to down when his is down it will still shut off the pump? he will have to make it opposite of mine again
 
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Old 06-17-16, 12:18 AM
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Are both apartments on the same phase? Where I live at least it's common that buildings balance the load by putting a 3rd of the apartments on each phase.

If that's the case that would explain the blown fuse (maybe) other wise I don't get it. It shouldn't matter that both switches are open.
 
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Old 06-17-16, 04:01 AM
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My answer was based on this building being located in Pennsylvania. You should probably change your profile so we know you are in Egypt.

There are probably several different methods that could be used. As I stated in my original response the "proper" method would to power the pump from the building's common areas power system rather than from a tenant's power. Low voltage relay control then from each tenant would switch the pump on or off as needed.

If you are willing to pay for the electricity for the other tenant's use of the pump then having a switch at the other apartment that simply parallels your switch is the easiest. Depending on how the local electric service is connected it may take only two wires or it may take four wires between the two switches. Do you know the voltage AND whether or not one line is grounded/earthed?

Added, my response is assuming that this pump has a single phase motor, if it is a three-phase model then more wires will be required.
 
  #12  
Old 06-17-16, 07:28 AM
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What I suggested allows any combination of switch positions.

If your switch is (let's say up and) supplying power to the pump then the other apartment switch (when off) sends nothing or (when on) sends power to a dead end in your switch. However the pump is already running on y our power for both of you so it does not matter if the other resident turns his switch off (or on).

If your switch is (let's say down and) not supplying power to the pump then the other switch (when off) sends nothing or (when on) sends power to your switch which immediately routes the power on to the pump. So now the other resident has full control over the pump.

There are some variations on the wiring but I chose this method so you don't have to touch anything in the other apartment.
 

Last edited by AllanJ; 06-17-16 at 08:02 AM.
  #13  
Old 06-17-16, 08:58 AM
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I would suggest installing a pressure tank downstream of the pump and also a high pressure cutoff switch so the pump does not overload. These components will smooth out the operation of the pump and prolong its life.
 
 

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