Motor starting from lighting switch

[sweet212]

Evening all.

My client has asked me to look into connecting a pump for their garden pond. The existing set up had a DOL starter positioned on a wall in the kitchen from which the pump was operated. (DOL starter now removed)

The new scenario is to turn the pump on via a switch in the 6 gang light switch arrangement. The pump will be over 0.37KW (probably around 0.8KW or so) so will need overload protection.

Could I run the control wiring through the light switch and back to a relay inside a box which would also house the overload protection?

Another option would be to install overload protection nearer the motor.

All single phase.

Any thoughts appreciated.

Many thanks.

 

[Squid]

Stick it on a timer with an override, why do they need it switched?

Customers all have airey fairy ideas it is up to you to guide and hand hold them and save them from their own stupidity.

 

[westward10]

How was the DOL starter supplied previously. Yes you could use a 6A switch on the control circuit of the original starter.

 

[sweet212]

How was the DOL starter supplied previously. Yes you could use a 6A switch on the control circuit of the original starter.

Hi Westward,

Do you mean final circuit supply or are you asking how was it switched previously?? The old pump was being operated by the green/red buttons on the starter unit. It was wired via 2,5mm TE on a 16A MCB. No seperate circuit for control wiring.

I can wire in remote stop starts no problem but cannot get my head around using say a 1 gang switch to operate both on and off functions. Is it just the case of it cannot be further operated by the green/red on offs on the DOL??

Many thanks, James

 

[westward10]

You could fit a contactor with overload relay to an enclosure controlled by momentary switch/es.

 

[Bellendian]

If it's a grid you could try an mk k4900 module, think that might do the trick in terms of having spring loaded 2 way positions and a central off position?

 

[Marvo]

Can't you reuse the original DOL starter and just wire a light switch to it as a remote signal for ON/OFF?

 

[Bellendian]

Yes, but wouldn't that effectively overide the NVR function? That said, even if it did, would that matter for a pond pump?

 

[westward10]

If it's a grid you could try an mk k4900 module, think that might do the trick in terms of having spring loaded 2 way positions and a central off position?

This was my thought so you have n/c for the stop and n/o for the start by way of a control circuit through a relay.

 

[Wilko]

Hi - perhaps find out what pump is proposed, as small pumps of this kind now often come with o/l built in.

 

[westward10]

What hp is the motor, less than 0.50 is does not require overload protection.

 

[Marvo]

Could be a problem with using a switch in an existing 6 gang. Not sure what your regs say about LV and ELV in the same switch assembly (if using 24v remote signal for example) or even multiple 230v supplies in the same grid switch.

 

[Deleted member 26818]

Can have different phases in a grid switch.
Pretty sure that the remote switches we used in the factory I worked in were 230V.
Don’t recall the star/delta boxes having a transformer inside.

 

[Lucien Nunes]

If you control a starter remotely using a 2-position switch (on/off) in the gridswitch, the pushbuttons would become non-functional. The holding contact would be disabled and the contactor coil just wired to the supply through the switch and O/L. You will not have NVR but provided the O/L relay's reset selector is set to manual, it will still stop the pump in case of overload until reset by pushing the red button.

If you require NVR, then an additional contactor is needed. One contactor / relay would 'store' the state of the buttons / NVR, i.e. operated after pressing the green button and released after pressing the red button or supply loss, and another would control the supply to the motor according to the position of the rocker switch.

Using a biased rocker switch (up)-off-(down) or two N/O pushbuttons in the gridswitch would enable the normal functions of the starter to remain unchanged, but a relay with one N/C contact would be needed to invert the off function from N/O. If you can find a N/C pushbutton then you've cracked it.

 

[sweet212]

If you control a starter remotely using a 2-position switch (on/off) in the gridswitch, the pushbuttons would become non-functional. The holding contact would be disabled and the contactor coil just wired to the supply through the switch and O/L. You will not have NVR but provided the O/L relay's reset selector is set to manual, it will still stop the pump in case of overload until reset by pushing the red button.

If you require NVR, then an additional contactor is needed. One contactor / relay would 'store' the state of the buttons / NVR, i.e. operated after pressing the green button and released after pressing the red button or supply loss, and another would control the supply to the motor according to the position of the rocker switch.

Using a biased rocker switch (up)-off-(down) or two N/O pushbuttons in the gridswitch would enable the normal functions of the starter to remain unchanged, but a relay with one N/C contact would be needed to invert the off function from N/O. If you can find a N/C pushbutton then you've cracked it.

Hi Lucien,

Your 3rd paragraph makes sense. If I use 2-way and off retractive switch, in the up (on position) it will act like a normal NO contact in parallel with the start button but when in down (off position) a NC relay will be needed to operate in series with the off button thus turning the pump off.

What do I need the NC push button for?

Many thanks,

James

 

[brianmoooore]

Assuming the pump is a self contained design, and not something involving pulleys and vee belts, then there is no danger from the motor starting unexpectedly, other than someone getting wet, so NVR is not required.

 

[Deuce]

What hp is the motor, less than 0.50 is does not require overload protection.

0.8 kw = approx 1hp. The limit for no OL protection is indeed 1/2hp

I assume this is an above ground pump? I would use a DOL module and if remote switching is required, use a suitable relay to carry out the on/off switching of the DOL module, in the same enclosure. I wouldn't switch power directly on the supply or load side of the DOL.

NVR not really required as there is no mechanical danger to be protected from if a surprise restart occurs. That said, if you/customer feel strongly enough about it, it's not at all difficult or expensive to build in NVR functionality. For the same reason, you shouldn't need a visible/accessible e-stop button (to the best of my knowledge).

To demonstrate how little of a concern NVR is for a pump, consider that submersible pumps that are sold with a household 3 pin plug are sold up to 1.5kw, and feature only basic thermal overload protection. such pumps are of course switched simply by... erm.. a switch

 

[Deuce]

Sorry I just realised I kept typing DOL in the enclosure, I meant the overload module.

However, just had a quick google and this seems to do all you need, it is configured for remote control too: https://docs-emea.rs-online.com/webdocs/1586/0900766b81586128.pdf