Question about float switch wiring.

Users who are viewing this thread

Mduncan60

New Member
Messages
7
Reaction score
0
Points
1
Location
Graeagle CA
I'm planning on setting up a well storage tank for my well. I have learned a lot on this forum. More than on any other website. But I just want to clarify something. The well pump is currently controlled by a pressure switch. The pressure switch opens and closes both the L1 and L2 circuits. I have always assumed that was necessary. But it seems that a float switch opens only one circuit. Am I understanding that correctly? That only one circuit needs to open and close to start and stop the pump.
 

Valveman

Cary Austin
Staff member
Messages
14,738
Reaction score
1,331
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
You can use a float switch to control the pump. Or, you can use a pressure switch and tank if the float switch controls a solenoid valve.

LOW YIELD WELL_ CENTRIFUGAL_PK1A.jpg


LOW YIELD WELL_and storage with two PK1A.jpg
 

wwhitney

In the Trades
Messages
6,650
Reaction score
1,877
Points
113
Location
Berkeley, CA
I'm planning on setting up a well storage tank for my well. I have learned a lot on this forum. More than on any other website. But I just want to clarify something. The well pump is currently controlled by a pressure switch. The pressure switch opens and closes both the L1 and L2 circuits. I have always assumed that was necessary. But it seems that a float switch opens only one circuit. Am I understanding that correctly? That only one circuit needs to open and close to start and stop the pump.
A circuit is a loop of wire, which typically includes both a power source and a load. So I believe you mean the pressure switch opens and closes both the L1 and L2 wires. But to interrupt a circuit it is sufficient to open one wire.

Cheers, Wayne
 

Mduncan60

New Member
Messages
7
Reaction score
0
Points
1
Location
Graeagle CA
A circuit is a loop of wire, which typically includes both a power source and a load. So I believe you mean the pressure switch opens and closes both the L1 and L2 wires. But to interrupt a circuit it is sufficient to open one wire.

Cheers, Wayne
Totally perfect answer. Exactly what I was thinking and now confirmed. Thank you.
 

Mduncan60

New Member
Messages
7
Reaction score
0
Points
1
Location
Graeagle CA
So Wayne, Im seeing that people are using a contactor or relay ? To interrupt the circuit, and others say you can wire it directly. What is the best way? And if it is to use a contactor, do you have a recommendation.
 

wwhitney

In the Trades
Messages
6,650
Reaction score
1,877
Points
113
Location
Berkeley, CA
My comments are generic and not specific to this application, as I have no experience with float switches, etc.

Often there's a requirement for both a disconnect and a controller. A disconnect should break all the ungrounded (hot) conductors, while a controller only need to break the circuit. So you'd use a disconnect to make things safe before working on it, but your controller (e.g. float switch) can leave a wire energized as long as there's no complete circuit.

For a 120V load, there's just one ungrounded conductor, so breaking a single wire works for both purposes. But for a 240V 2-wire load on a standard residential 120V/240V system, there are two ungrounded conductors, so your disconnect would need to break both, while a controller could get away with breaking one. Often when a disconnect is required, the breaker supplying the circuit can be the requisite disconnect, possibly with a requirement for permanent means for attaching a lock to the breaker if the breaker is not in site of the equipment.

As to a relay, it's useful in a couple cases: (1) one is that your controller has a load limit, and you want to control a larger load. So the controller controls power to the coil of the relay, and then the relay controls power to the load. (2) you're limited for whatever reason to one type of incoming control signal (say making/breaking one pair of wires), and you need another type (different logic, or multiple sets of wires). The few times I've needed one, I've used something from "Relay In A Box" as it was very conveniently prepackaged for me.

Anyway that's the general background, now you can try to figure out how the above applies to your application.

Cheers, Wayne
 
Last edited:

Fitter30

Well-Known Member
Messages
4,493
Reaction score
841
Points
113
Location
Peace valley missouri
Will using a float switch cycling half the power yes. But i don't want the potential of 120vac going to ground. Two pole 25 amp 120vac coil contactor and a box would take care of it.
 

wwhitney

In the Trades
Messages
6,650
Reaction score
1,877
Points
113
Location
Berkeley, CA
Will using a float switch cycling half the power yes. But i don't want the potential of 120vac going to ground.
It won't, the float switch just needs to be rated for the current and voltage it is interrupting. Once the circuit is interrupted, it won't matter that the two sides of the switch are 240V to each other and each 120V to ground.

Cheers, Wayne
 

Mduncan60

New Member
Messages
7
Reaction score
0
Points
1
Location
Graeagle CA
This is all great knowledge. Different opinions but that's OK. I think I am able to make an educated decision. Thank you all for your input. More opinions are always welcome.

Marvin
 

Mduncan60

New Member
Messages
7
Reaction score
0
Points
1
Location
Graeagle CA
My comments are generic and not specific to this application, as I have no experience with float switches, etc.

Often there's a requirement for both a disconnect and a controller. A disconnect should break all the ungrounded (hot) conductors, while a controller only need to break the circuit. So you'd use a disconnect to make things safe before working on it, but your controller (e.g. float switch) can leave a wire energized as long as there's no complete circuit.

For a 120V load, there's just one ungrounded conductor, so breaking a single wire works for both purposes. But for a 240V 2-wire load on a standard residential 120V/240V system, there are two ungrounded conductors, so your disconnect would need to break both, while a controller could get away with breaking one. Often when a disconnect is required, the breaker supplying the circuit can be the requisite disconnect, possibly with a requirement for permanent means for attaching a lock to the breaker if the breaker is not in site of the equipment.

As to a relay, it's useful in a couple cases: (1) one is that your controller has a load limit, and you want to control a larger load. So the controller controls power to the coil of the relay, and then the relay controls power to the load. (2) you're limited for whatever reason to one type of incoming control signal (say making/breaking one pair of wires), and you need another type (different logic, or multiple sets of wires). The few times I've needed one, I've used something from "Relay In A Box" as it was very conveniently prepackaged for me.

Anyway that's the general background, now you can try to figure out how the above applies to your application.

Cheers, Wayne
Thank you for the detailed breakdown. And yeah, I would never not have a disconnect, and in sight of the equipment. I do understand the concept of the relay. It's the same as in an automotive application which is my line of knowledge. Use of a relay is always the safest way to go in automotive which is why I'm leaning in the direction.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks