Hi There,

 

I recently installed a biomek 0.75kw centrifuge pump from a jojo tank to feed the water mains on my house. 
 

I’ve been experiencing this issue with the LED lights in my house flickering when the pump starts.

 

Its on a plug circuit for the garage with a 20A breaker. I have a LuxPower SNA5000 powering this circuit (and others). The issue happens when there is grid and when it’s on EPS. 
 

From what I read this can be because the pump is causing the voltage to drop and the LED lights are sensitive to voltage changes. 
 

How do I diagnose this? Do I measure the voltage at the pump when it starts to see if this is the case? 
 

I like to understand what is going on when I have electrical or plumbing issues which is why I would like to try and diagnose as much as I can before getting an electrician out, that way I will learn more

thanks in advance 

 

Devices with motors often have large inrush current when they start up which can indeed cause a momentary voltage drop when they start, since such devices can pull 3 or 4 times their rated current when they turn on.

I notice the same from my non-inverter air cons (whenever the compressor kicks in) as well as my non-VSD pool pump.

Usually its not a safety concern although perhaps it's not great for more sensitive electronics of it happens all the time - but swapping over to a soft-start VSD based pump will resolve this by removing the large current inrush on startup. (My own VSD JoJo pump doesn't cause flickering, unlike my non-VSD pool pump).

Thanks for the feedback, I do notice it with my Aircons too. But it doesn’t seem as extreme, also the pump kicks in quite frequently when there is a running water so the light flickering can be quite obvious. Starting to think not spending the extra cash on a VSD was a bad idea. However I did a lot of research and i did not ever read about this problem (even though the reason for it make sense)

without replacing my brand new pump, are there any other options? I did read about soft starters, but they also don’t seem to be a cheap fix (not looking for one, but comparing the cost of that vs a new pump, makes more sense to go with pump)

Adding a pressure tank wouldn't solve the issue but I'd imagine it would reduce cycling (because the pump wouldn't have to power on as frequently).

 

But yeah, for us, this issue coupled with needing to run off inverters (with limited current/power capacity) for PV has had our household slowly moving everything to soft-start. Our latest air con is an inverter unit: it gradually ramps up power instead of slamming our system every time the compressor powers on and consumes noticeably less overall power to boot. Our non-VSD pool pump is on our inverter's Aux port but because it powers on just once a day, it doesn't matter as much.

 

I've also noticed that some of my LED lighting (especially my smart-bulbs) seem more immune to this issue than others.

 

Sorry I haven't any better solutions for you: hopefully some others can chime in here!

Edited December 1, 20241 yr by JayMardern

As already noted, many pumps (a pump is a motor for electrical purposes) draw a lot of current to start up. A VSD pump or an inverter pump will draw it's rated power, but because it speeds up gradually will not have the spike as it starts up.

You are not looking for fluctuations in voltage, but for large current draws.

Last year we bought a new freezer. The old one pulled 1365 W on startup. The new one (inverter drive) showed a much lower peak of of 108 W.

There are "soft starter" devices that you can put in line with the motor. These have the effect of spinning the motor up slowly. I'm not an electrician, so I can't tell you more than that.

 

Edited December 2, 20241 yr by Bobster.

Get one of these. You place it between the socket and whatever you want to monitor. It will record total power used over the measuring period, and low and high momentary draws. Very handy if you have an inverter (also for settling arguments). This is how I was able to get the figures above for the old and new freezers.

11 hours ago, Timbo said:

Hi There,

 

I recently installed a biomek 0.75kw centrifuge pump from a jojo tank to feed the water mains on my house. 
 

I’ve been experiencing this issue with the LED lights in my house flickering when the pump starts.

 

Its on a plug circuit for the garage with a 20A breaker. I have a LuxPower SNA5000 powering this circuit (and others). The issue happens when there is grid and when it’s on EPS. 
 

From what I read this can be because the pump is causing the voltage to drop and the LED lights are sensitive to voltage changes. 
 

How do I diagnose this? Do I measure the voltage at the pump when it starts to see if this is the case? 
 

I like to understand what is going on when I have electrical or plumbing issues which is why I would like to try and diagnose as much as I can before getting an electrician out, that way I will learn more

thanks in advance 

 

This is quite normal. I used to see this with my espresso machine which has a beefy pump for pressuring the water to 15 bar.

Things that improved the flickering:

- Adding more batteries in parallel.

- Going from a 12V to 48V system. 

- Installing better quality LEDs in the house.

- Installing a stronger inverter. I went from a 1000W to 5000W inverter.

- Install a pump starter. From my understanding it is basically just a big capacitor over the terminals that can deliver a large current burst when the pump starts.

 

A 1.1 kW swimming pool pump for instance operates at 230V AC with a running current of 4.8A. During startup, the motor can draw approximately  28.7A (6.6 kW) for the first second or two, depending on factors such as temperature, starting angle, load, and other conditions. All HF inverters have a voltage sag if inductive loads are applied for a few milliseconds. The low frequency inverters like Victron cope much better with inductive loads. You could get an external single phase VSD for your existing pump but they are not cheap. Like @JayMardernsaid some led bulbs are more susceptible to voltage changes so your cheapest option might be to try different led ranges.
 

1 hour ago, Bobster. said:

Get one of these. You place it between the socket and whatever you want to monitor. It will record total power used over the measuring period, and low and high momentary draws. Very handy if you have an inverter (also for settling arguments). This is how I was able to get the figures above for the old and new freezers.

Thanks for this, i have a Shelly PM Mini wired into it, but i dont think its capturing the spike because its too quick. will get my Fluke on there and see what the current spike is. 

56 minutes ago, HendrikBigChief said:

This is quite normal. I used to see this with my espresso machine which has a beefy pump for pressuring the water to 15 bar.

Things that improved the flickering:

- Adding more batteries in parallel.

- Going from a 12V to 48V system. 

- Installing better quality LEDs in the house.

- Installing a stronger inverter. I went from a 1000W to 5000W inverter.

- Install a pump starter. From my understanding it is basically just a big capacitor over the terminals that can deliver a large current burst when the pump starts.

 

Thank you, this is good feedback. I will go see if my local electrical shop can advise on alternative brand LEDs. as a start.

12 hours ago, JayMardern said:

Adding a pressure tank wouldn't solve the issue but I'd imagine it would reduce cycling (because the pump wouldn't have to power on as frequently).

 

But yeah, for us, this issue coupled with needing to run off inverters (with limited current/power capacity) for PV has had our household slowly moving everything to soft-start. Our latest air con is an inverter unit: it gradually ramps up power instead of slamming our system every time the compressor powers on and consumes noticeably less overall power to boot. Our non-VSD pool pump is on our inverter's Aux port but because it powers on just once a day, it doesn't matter as much.

 

I've also noticed that some of my LED lighting (especially my smart-bulbs) seem more immune to this issue than others.

 

Sorry I haven't any better solutions for you: hopefully some others can chime in here!

Thanks for your input, really appreciate it.

 

I also noticed this, my dimmable downlights arent impacted. Ive got some of those big LED filament bulbs that are impacted the most.  I will see if the are replaceable with something more tolerable. 

Also the pressure tank is on my list, as the pump runs really frequently at the moment and would like to reduce the wear on it.

 

7 hours ago, Timbo said:

Thanks for your input, really appreciate it.

 

I also noticed this, my dimmable downlights arent impacted. Ive got some of those big LED filament bulbs that are impacted the most.  I will see if the are replaceable with something more tolerable. 

Also the pressure tank is on my list, as the pump runs really frequently at the moment and would like to reduce the wear on it.

 

When my tank & pump were installed I had a bright idea. But the plumber had already had the same idea. That is a tap on the municipal line before the tank. You can use that tap all you like. It will work at municipal pressure (when that is present) and will not affect your tank nor cause the pump to run. So use that for, say, garden sprinklers (not that any civic-minded person in Johannesburg would run those whilst the sun is in the sky. Heaven forfend!). 

So the pump only runs when water is used in the house or when the washing machine is on. In our circumstances (2 adults, appliances set for minimal water use) this means the pump doesn't work too hard.

9 hours ago, TaliaB said:

A 1.1 kW swimming pool pump for instance operates at 230V AC with a running current of 4.8A. During startup, the motor can draw approximately  28.7A (6.6 kW) for the first second or two, depending on factors such as temperature, starting angle, load, and other conditions. All HF inverters have a voltage sag if inductive loads are applied for a few milliseconds. The low frequency inverters like Victron cope much better with inductive loads. You could get an external single phase VSD for your existing pump but they are not cheap. Like @JayMardernsaid some led bulbs are more susceptible to voltage changes so your cheapest option might be to try different led ranges.
 

This is a really good plan, I think changing the LEDs is probably the most appropriate short term quality of life improvement. I noticed my dimmable LEDs aren’t affected by this so might start with that in one room and see how it goes.

1 hour ago, Bobster. said:

When my tank & pump were installed I had a bright idea. But the plumber had already had the same idea. That is a tap on the municipal line before the tank. You can use that tap all you like. It will work at municipal pressure (when that is present) and will not affect your tank nor cause the pump to run. So use that for, say, garden sprinklers (not that any civic-minded person in Johannesburg would run those whilst the sun is in the sky. Heaven forfend!). 

So the pump only runs when water is used in the house or when the washing machine is on. In our circumstances (2 adults, appliances set for minimal water use) this means the pump doesn't work too hard.

I had a similar idea, I have a tap by the gate, and then my PRV at the house. I installed the tank before the PRV at the house and put the non return valve after the feed from that tap by the gate. So that tap is always off municipality. 
 

which is never used for watering grass in the rainy season of Durban 😆

anyway, I was bothered by the lights when sitting in bed with those LED filament lights on (seemed like a great idea at the time) trying to give me a migraine (or start a party depending on how you look at it) when someone flushes the toilet 😅

14 hours ago, Timbo said:

I had a similar idea, I have a tap by the gate, and then my PRV at the house. I installed the tank before the PRV at the house and put the non return valve after the feed from that tap by the gate.

Sorry, what is a PRV? 

38 minutes ago, Bobster. said:

Sorry, what is a PRV? 

Pressure Reducing Valve,  so your geyser doesnt go boom

1 minute ago, Timbo said:

Pressure Reducing Valve,  so your geyser doesnt go boom

Thanks. I actually am familiar with those devices.

I wanted to close the loop on this post for anyone else that stumbles upon my bad luck. 
 

I found that Osram/Ledvance dimmable LED GU10 bulbs (glass) ones are not impacted by the water pump. I tried a couple brands, interestingly an old set of Synerji dimmable bulbs are also not impacted however a new set I bought is. So the components must of changed. 
 

im still looking for a replacement filament type bulb, tried LEDworx from builders and no luck. I see osram/Ledvance have a 7w version. Gonna order a pair of them and hopefully will get lucky. 

Can a booster pump also cause this flickering even when it's not on the same circuit with led lights

yes, the pump can cause a voltage drop (due to the high draw nature of the inductive load). When the voltage drops you see the light flicker, especially with LED bulbs. incandescent bulbs were less susceptible to voltage drops because of the heat they generate. (im sure chatgpt can explain the science better than i can).

I even see it with my new bulbs when the grid voltage is below 220, and the pump kicks in. like right now its 215 ish which means everything is abit sensitive atm:



If you want to avoid this buy a variable speed or HMS pump, Its a lesson i learnt. Spent tons of time researching and never considered the impact the pump would have on my house electricity. i hindsight i should have gotten a Variable speed pump instead.

Another lesson was that the normal Centrifuge pumps are all cast iron inside, so for the first few months you will see rust in the water that comes from the tank, especially after the pump has been standing a while (like overnight for example). This goes away after some time as after a couple months of it being a "closed circuit" there isnt really any oxygen in there to oxidise the iron and cause rust.

Edited June 5, 20251 yr by Timbo

7 hours ago, Timbo said:

yes, the pump can cause a voltage drop (due to the high draw nature of the inductive load). When the voltage drops you see the light flicker, especially with LED bulbs. incandescent bulbs were less susceptible to voltage drops because of the heat they generate. (im sure chatgpt can explain the science better than i can).

I even see it with my new bulbs when the grid voltage is below 220, and the pump kicks in. like right now its 215 ish which means everything is abit sensitive atm:



If you want to avoid this buy a variable speed or HMS pump, Its a lesson i learnt. Spent tons of time researching and never considered the impact the pump would have on my house electricity. i hindsight i should have gotten a Variable speed pump instead.

Another lesson was that the normal Centrifuge pumps are all cast iron inside, so for the first few months you will see rust in the water that comes from the tank, especially after the pump has been standing a while (like overnight for example). This goes away after some time as after a couple months of it being a "closed circuit" there isnt really any oxygen in there to oxidise the iron and cause rust.

Not always necessary to change the pump. Just get a soft starter for the pump. If the pump is started at a say 110V and then connects to 230V the LEDS might not dim.

What is the pump rating, length of cable and size of cable? You could install some running capacitors to provide reactive power.

It’s a 750W pump. When you say length of cable are you asking from the DB board or from the plug?

it’s wired into the garage plug circuit which is quite far from the db board, maybe 40m of cable. 2.5mm all the way.

I have a c curve breaker on that circuit.

I tried to research soft starters, but it’s hard to find local info and what I did see on the forum is opinions that they are pricey (might be similar to a vsd pump if you combine the cost of the centrifuge pump and starter).

Interested in the capacitor idea, what would that involve?

2.5mm² is probably ok, but a dedicated circuit would be better.

LV power factor correction caps start at a few kVAr and few kRand. But it couldn't hurt to install a few running capacitors close to the motor to supply all reactive current.