A bonding question I can't find the answer to

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T

Towebud

Member
Feb 13, 2021
6
Orlando
16804604780335175782812287843749.jpgmy pump motor has been replaced for the third time in 5 years. I moved to Orlando on 2017, and this is my first pool. We replaced the pump, but have had corrosion issues on the motor. I have searched this forum and other places for answers as to what would cause this, and I keep coming back to the bonding wire. I bought new 8 guage bare copper wire and asked him to redo the bonding, but he said that's not the problem. I told him the corrosion occurs within 3 months of the motor being replaced. He says that's unusual but it's indicative of a seal leak within the pump. So, even though I had new wire, he said it doesn't need it. I've included pics of all of the bonding and what's strange to me is that it looks like it's grounded to the house and the junction box. 16804605037264998580539650776254.jpgthis is the pool heater16804605275375993780425588433020.jpgthis is on the side of the house16804605483428888297892410850083.jpgthe blue wire snakes to the left and up the conduit (it has house paint on it), while the green wirw goes along the side of the house and is in the previous pic16804605753951443743402009897949.jpgthis blue wire goes to the pool cage 16804605975288659781885281760065.jpg
What am I missing?
 
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Towebud said:
I've included pics of all of the bonding and what's strange to me is that it looks like it's grounded to the house and the junction box.
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[EDIT for clarification] Normally, the bonding wire is attached to the pump housing which itself is grounding so it is normal that the bond has a direct connection to the house ground. Why the installer put a separate wire to do that, I do not know but it shouldn't really hurt anything as long as it is connected to the house ground.

Do you have any pictures of the old pump?
 
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JoyfulNoise said:
I don’t think the nature of bonding wire has anything to do with it. We need to see what the previous motor corrosion looked like and where on the motor it was found.
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My comment was more around the knowledge of the electrician. Seems like code has changed so I can walk it back, assuming the insulated wire is only used above ground. If it were used underground, a big portion of the purpose of bonding would seem to be defeated.
 
Here is the pump before it was replaced. Also, from your responses, it sounds like I don't need to replace the bonding wire, even though it looks like it's grounded to the house and maybe a junction box. It's that correct?
 

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Towebud said:
Here is the pump before it was replaced. Also, from your responses, it sounds like I don't need to replace the bonding wire, even though it looks like it's grounded to the house and maybe a junction box. It's that correct?
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You don’t need to replace the bonding wire, it’s fine.

That type of corrosion is called “white rust” and it’s a failure of the galvanized coating on the pump motor casing. Its also known as “wet storage stain” and It’s typically caused by a zinc that is allowed to get wet and sit in a damp spot with little airflow. In your case, the zinc is the galvanized coating on the metal casing (probably a low grade steel) of the electrical motor body that is then painted over. TFP has had reports of this corrosion many times in the past and I believe there is a problem with the paint being used or the process by which it is applied by the manufacturer. It’s not Pentair’s fault per se as they just buy the electric motor from the manufacturer. It’s the motor manufacturer that has the problem. I could go into the detailed chemistry of white rust but that’s not important.

The only way to fix it or avoid it is to make sure the pump stays dry. Does this pump get wet a lot? Is there a lot of water in that area ? When it rains does the pump sit in a puddle of water? Is it humid all the time?

The pump needs to be elevated off the ground and kept as dry as possible or else the same problems will occur.
 
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I live in Orlando, so yes, it gets wet and yes, it's humid-very humid 4 months out of the year. Here are pictures of the pump before that one (so 2 pumps ago, in 2020). Same issue. I've read about the white rust, so if it's a manufacturing issue, maybe I switch to the hayward pump in the future.
 

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Switching is up to you. If you have a Pentair automation system then you can only use Pentair pumps as it won’t control other manufacturers equipment.

The equipment needs to be kept as dry as possible. Any pump sitting in wet ground or getting wet all the time is going to fail sooner than expected. You should open a complaint with Pentair and let them know that this is your third pump that has been replaced due to the same corrosion failure. They can’t fix anything if they are not aware of it. Don’t reply on a pool guy to do that as they are simply installers and don’t really care how things fail or why.
 
Towebud said:
A magnet doesn't stick
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It's probably aluminum.

Aluminum is odd because it resists corrosion well for a long time but it can corrode rapidly under certain circumstances.

Typically, the corrosion is due to a seal leak.

You can also get stray currents which can accelerate corrosion.

The aluminum is anodic to most other metals that are bonded.
 
JamesW said:
It's probably aluminum.

Aluminum is odd because it resists corrosion well for a long time but it can corrode rapidly under certain circumstances.

Typically, the corrosion is due to a seal leak.

You can also get stray currents which can accelerate corrosion.

The aluminum is anodic to most other metals that are bonded.
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If it is aluminum (much more likely than magnesium $$) there is a multimeter test you might try that may help point you in the right direction.

Run one lead of the multimeter from some metal on the housing of the pump to a solid electrical ground point with the pump running. If the meter shows any voltage, that’s an indication that voltage may be building up and causing the corrosion. I had a similar issue with an aluminum radiator on a custom truck. A way I found to stop it was to electrically ground the aluminum body of the radiator. If no voltage is present, then look elsewhere for the cause.
 
What is behind this plate?

16804605275375993780425588433020-jpg.479993
 
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