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 What conductor triggers 240v cable float switch
Author: dancarp (Non-US)

I searched the forum without success for this.

I have a 240v effluent pump that just pumps water. It is located in my basement sump pit and is only functional 2 or 3 times a year to pump 'mountain run-off' in excess of drainlines. I also have a 115v effluent pump set at a higher level. The combination of these pumps on full time pump 7000gallons/hr to keep my basement dry.

Both pumps have cable float switches. On the 115v I can plug in a 3way to turn on a light when it comes on so I can monitor. This was my primary pump at one time with a smaller one but inadequate volume.

I purchased a more powerful 240v since it uses less power but I am unable to find a 3way for 250/20amp recepticle to plug in a 115v light.

I have created a system from the piggyback using one hot conductor leading to a 115v receptacle (and 2 to the pump) which is good, but there is power there without the 240v pump running or turned on. Then I checked the piggyback and there is power there as well if I ground to the electric box.

Question: in a 240v cable float switch, is the connection to switch the pump on determined by the ground wire?

If that is so, then I need to unground my receptacle & box and tie the ground specifically to the 240v piggyback system. Can anyone confirm this?

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 Re: What conductor triggers 240v cable float switch
Author: m & m (MD)

The float is probably only breaking one side of the 230 volt, meaning that there is a constant 115 volts present at the motor all the time. No, the ground does not come into play for the float operation.

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 Re: What conductor triggers 240v cable float switch
Author: Fixitangel (NC)

Quote: Question: in a 240v cable float switch, is the connection to switch the pump on determined by the ground wire?

The answer is NO. The ground is for safety in case of a short.

How many conductors are in the cable of the 240 volt float switch? If it's only 2, you might have an SPST switch that uses 120volts to switch a relay in the pump. Can you post a wiring diagram of the 240 volt pump?



Edited 1 times.

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 Re: What conductor triggers 240v cable float switch
Author: hj (AZ)

Any good 240 V pump switch would be a DPST to break BOTH sides of the power supply. 240 v pumps do NOT use "less power". The wattage is the same, the amperage just changes. Depending on HOW the switch works, you may not be able to "intercept" the load side of it.

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 Re: What conductor triggers 240v cable float switch
Author: Fixitangel (NC)

We need to keep in mind that the poster is of Non-US origin. There are basically 2 major wiring standards, the North American (120 volt/60 Hz.) and the European standard (240volt/50 Hz.) Single phase residential.

It could be that a European 240v/50 hz pump only has 2 conductors, The Hot, and the PoCo neuteral, (no local earth ground). If such were the case, a 2 wire pump switch could be used to interrupt the hot leg, while the neutrual is the return path.

We would need to know the local power hookup and pump wiring connections to advise how to hook up a "3-way" (whatever that means) to make a 120 volt light monitor bulb work.

Call a sparky.

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 Re: What conductor triggers 240v cable float switch
Author: hj (AZ)

If that were the case he would not have the 110/120 v. current he says he uses for the other pump and light.

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 Re: What conductor triggers 240v cable float switch
Author: dancarp (Non-US)

We would need to know the local power hookup and pump wiring connections to advise how to hook up a "3-way" (whatever that means) to make a 120 volt light monitor bulb work.


3-way is an adapter to allow 3 plugs to be used. On my 115v pump, I plug the 3way into the piggyback, then plug the pump and a trouble light into the 3way. When the pump comes on the light comes on. If I could fine a 250v/20amp 3way problem solved..but I can't find one.

power hookup is 2 - 120v 15amp conductors and ground to a 250v/20amp receptical.

According to the Myers Pump website, the float switch has a ball and two arms that complete the connection when high level is reached which in theory powers the piggyback receptacle. I hooked a 250v/20amp plug(into piggyback receptacle) to a second 250v/20amp receptacle so I could split off a 120v feed.

I fed 1 conductor leading to a 120v receptical to plug in the light(neutral from another 120v receptacle) and receptical was live. I thought perhaps the piggyback had 1 live and 1 dead with float switch off, so I switched the feed to the other conductor and it was also live at the 120v receptacle. My 115v system is setup the same way and it works fine.

My 230v pump is my primary and my 115v is secondary in the event the primary cannot keep up and is also becomes a backup to the primary.

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 Re: What conductor triggers 240v cable float switch
Author: hj (AZ)

quotw; If I could fine a 250v/20amp 3way problem solved..but I can't find one.

And you will not. It would create a very dangerous condition if one were used, and it would NOT split the wiring into 240 and 120 circuits even if there were one.

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 Re: What conductor triggers 240v cable float switch
Author: dancarp (Non-US)

Thanks. I was going to buy 240v bulbs but figured someone would put them in a 120v socket, so I am trying to ensure a safe system.

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 Re: What conductor triggers 240v cable float switch
Author: hj (AZ)

They would usually have a much different base, such as a "mogul", so it could not happen. But even if it did the bulbs would just burn dimmer. It would be like the person who moved into our neighborhood many years ago. He put up all his Christmas decorations and wondered why they were all dim yellow. He had brought them with him from Poland and they were all 220 volt bulbs.

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 Re: What conductor triggers 240v cable float switch
Author: dancarp (Non-US)

I thought this was a possibility and then switched my 120v feed to the other side but still somehow had power. It is possible I did a double switch on wires and re-invented the same problem. In any event, if this is the case where the switch breaks only one side, that is the side I want for my 120v feed.

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 Re: What conductor triggers 240v cable float switch
Author: dancarp (Non-US)

THANK YOU, THANK YOU THANK YOU for all your responses. I have traced the manufacturer of the float switch and requested a wiring diagram of the switch and piggyback so I can get this done right.

Your time and effort is most appreciated.

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 Re: What conductor triggers 240v cable float switch
Author: Fixitangel (NC)

To connect a 120 volt monitor light bulb to your 240 volt pump you would need to "tap in" to the panel neutural and the "load" side of the SPST switch at or just after the piggy back. There are no commercial plug in adaptors that will work that I know of. Problem is the prong pattern is always different on 240 volt plugs vs. 120 volt.

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 Re: What conductor triggers 240v cable float switch
Author: Fixitangel (NC)

Now I understand. If you connect one side of a 120 volt lamp to neuteral, then the other side to the hot of the 240 volt switch, it would stay on. If you connect it to load side of the 240 volt switch, it would STILL turn on; the reason being that your voltage reference is then derived THRU the motor windings although it would be somewhat decreased due to the resistance of the motor. In that case the 120 volt lamp would not be a true On/Off indicator; it would be more half-on to fully lit.
You would need a switching relay or a 240 volt bulb across the motor leads to give a true on/off indication.

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