Arcing Pump Pressure Switch!

[chazman]

My Furnas AS4FX pressure switch makes arcing like 2 to 3 times, sometimes even 4 times, when it is trying to shut off the pump when it reaches the cut-out pressure (50 psi). It does not cleanly shut off the current to the pump. But there is no arcing at all when it engages the current as the water pressure drops to the cut-in pressure (30 psi). The contacts at the switch look carbon black due to the arcing.

What causes the multiple arcing when the switch is trying to disconnect the current?

 

[Waterwelldude]

The tube that the switch is mounted on is stopped up.
Did this start all of a sudden, or has been getting worse over time.
If you have not moved the switch and it has been where it is the whole time, its the tube or nipple its mounted on.
Turn the power off first.
Take the switch off and clean the pipe or pvc tubing its mounted on.


Travis

 

[Sponsor]

 

[chazman]

OK, thanks. I will try to clean the pvc tubing.
The switch was installed by a professional pump guy about a year and it started to arc like that since about a couple of months ago.

Question, I am guessing that dirt/debris in the pvc tubing is providing incorrect (or fluctuating) pump cut-out pressure to the switch, am I right?

 

[Waterwelldude]

Most I have seen have been stopped up by minerals in the water.
And yes, it will cause the switch to receive slow fluctuating signals.

 

[chazman]

Minerals in the water.... Yep, that makes a perfect sense!
Our well water is very hard, indeed, and that must be it.

BTW, do you have any preference in brands for the pump control pressure switch? When my previous Gould's jet pump went out, the pump guy removed the old Square D switch and installed a Furnas switch P/N AS4FX. I am thinking to replace the current Furnas because the contacts might have errorded due to excessive arcing for last 2 months or so. But I don't know which brand is most reliable.
Thanks again.

 

[Waterwelldude]

I like the Square D, but that's me. They make it easy to see if there pitted or burned.

 

[Ballvalve]

Pretty early for a mineral caused failure. And minerals would effect cut in as well as cut-out switching. Have you checked to see if the pressure tank is working correctly [waterlogged?] Is there any water hammer in the pipes when shutting off?

Could be a check valve issue causing the water to "bounce" the contacts at shut off. If the contacts open-close-open close at shut off, listen and feel for water in your pipes jumping around. Try to shut off the contacts by pushing them shut prior to pump off manually with a dowel or insulated tool. If you see the pump spring and diaphragm moving up and down, you have other issues than plugged tubing.

You can buy replacement contacts for most switches and not have to disturb the plumbing when repairing it. Be sure the switch is on a tall riser, say 5" of plastic and then a plastic or SS 1/4" nipple another 3 or 4 inches. This gives you an upward "trap" and keeps sediment out.

Swap the switch, and raise it up, but I think you might be on the wrong track.

I had a well that caused the pressure switch to do exactly what yours does at shut off, and by raising the cut-out pressure to 70 psi, it was remedied. I guess the lower flow at the moment of shutoff caused a reduction in water hammer . Water does not like to be stopped in its travel abruptly, and if you have a high flow pump and close it down fast, the water will cycle back and forth for a few travels until the pressure surge dissipates. Or a pipe breaks. The diaphragm in the pressure switch acts like a little pressure tank and absorbs the bounce, causing the contacts to cycle.