The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 10
Texas_Ranger 8
Trumpy 8
sparkyinak 7
Who's Online
1 registered (LongRunner), 90 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#2578 - 07/13/01 01:00 PM Swimming Pool
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
One of my customers has an indoor swimming pool. The copper pipes in the pool are being eaten away to the point of failure. Sacrificial copper pieces were placed in the pool and have also corroded. This pool is not plumbed to the house water system. The pool is filled from well system and uses bromine as the base chemical.

All metal parts are grounded and no potential can be measured between any two different metal surfaces. However, there is a +0.5VDC potential between the water surface and the ground grid. It appears that this pool has become a battery.

Any suggestions?

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#2579 - 07/13/01 04:58 PM Re: Swimming Pool
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Hi JBD !

so you have a battery created by chemical means, quit the chemicals...?

Top
#2580 - 07/13/01 06:06 PM Re: Swimming Pool
silverbk Offline
Member

Registered: 02/24/01
Posts: 61
That's exactly what a battery is. A big pool giving up electrions.

Top
#2581 - 07/13/01 07:40 PM Re: Swimming Pool
Anonymous
Unregistered


The most obvious solution is to eliminate any surfaces of dissimilar metals.

Plating, enameling, painting, replacement with non-metallic, etc., are possibilities.

You can't mix copper and any other metal.
If the pool is aluminum, no metal except aluminum in the pool.
If the pool is steel, no metal except steel in the pool.

Proper grounding can make the corrosion worse!

You could try applying a strong negative bias onto the pool, like -30 V DC. But getting rid of the all but one metal is the only real solution.

Top
#2582 - 07/14/01 03:07 AM Re: Swimming Pool
Phil H Offline
Member

Registered: 04/14/01
Posts: 24
Loc: Tujunga, CA
I'd look for too much bromine and/or low pH (acidic) first. If the pool is carbon steel or aluminum with copper piping, the steel/alum are more anodic and would more likely be the victim of galvanic corrosion rather than the copper.

Dsparks, are you aware that the purpose of the bonding grid in a swimming pool is to eliminate voltage gradients. And, if there is water in a swimmers ear, voltage gradients as low as 4V is enough to cause disorientation and drowning. Have you ever seen impressed current cathodic protection or similar used in swimming pools, I am aware of it's use on tanks, pipelines and boats. My gut instinct is to strongly oppose your casual suggestion to toss a charge into the pool and see if it stops the corrosion.

Phil H

Top
#2583 - 07/14/01 03:13 AM Re: Swimming Pool
Anonymous
Unregistered


>are you aware that the purpose of the bonding grid in a swimming pool is to eliminate voltage gradients.
Yes, I was just musing that bonding won't stop corrosion.

>Have you ever seen impressed current cathodic protection or similar used in swimming pools, I am aware of it's use on ... boats.
...boats with people swimming around them.

>toss a charge into the pool
I meant to say 'onto' the metal/bonded part, not 'into' the water!

Top
#2584 - 07/16/01 10:25 AM Re: Swimming Pool
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
The pool is a "poly-concrete" construction. The plumbing is copper, PVC, and ABS. The only metal surfaces in the water are: a stainless steel ladder connected to brass fittings (which are bonded), the cast iron drain grates, and the lighting fixtures. This is basically a typical in-ground construction, the only difference is bromine instead of chlorine.

We are checking with water professionals, but we wanted to rule out basic electrical possibilities.

Top
#2585 - 07/17/01 05:31 PM Re: Swimming Pool
moose Offline
Junior Member

Registered: 07/17/01
Posts: 1
Loc: yaphank, ny usa
Copper pipes in pool plumbing and pool heaters usually start to "rott away" and corrode because the ph and alkalinity of the water is very low and the chlorine or bromine is very high. Once the ph gets lower than about 7.4 and the alkalinity gets lower than about 70ppm, the oxidizer (in this case bromine) becomes very reactive.

Most pool pipes and fittings are plastic and this water condition will not adversly affect them - however if copper pipes are used - or if the pool has a heater on it - the copper will start to corrode. I believe this is what is probably happening to this subject pool. I would take a water sample to a local pool store and have them do a complete water test on it.

I predict it will be low ph & alk and high in bromine. I would add a sequestering agent / demineralizer to the water to try to lock up the existing chemical reaction. Then I would adjust the ph & alk a little on the high side (7.8 PH and 150 alk). Then I would adjust the bromine to about 2.0 ppm. This should keep the water relatively odorless, clear and non-corrosive to the pipes.

 Quote:
Originally posted by JBD:
One of my customers has an indoor swimming pool. The copper pipes in the pool are being eaten away to the point of failure. Sacrificial copper pieces were placed in the pool and have also corroded. This pool is not plumbed to the house water system. The pool is filled from well system and uses bromine as the base chemical.

All metal parts are grounded and no potential can be measured between any two different metal surfaces. However, there is a +0.5VDC potential between the water surface and the ground grid. It appears that this pool has become a battery.

Any suggestions?


Top
#2586 - 07/17/01 05:47 PM Re: Swimming Pool
Anonymous
Unregistered


>My gut instinct is to strongly oppose your casual suggestion to toss a charge into the pool
http://dailynews.yahoo.com/h/wjla/20010717/lo/no_charges_to_be_filed_in_lake_electrocution_1.html

Top
#2587 - 07/17/01 05:55 PM Re: Swimming Pool
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Moose,

Thanks for the Comments.
Original Name !! (his dog's name)

I know "Moose" you can visit him at:
http://www.poolandspa.com/
Biggest Pool & Spa site on the net!

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals