Salt water attacking wire insulation?

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CPM

Member
I manufacture products for metal detectors that are used in salt water. I was about to recommend taping (with black electrical tape) an electrical wire to a shaft but have been questioned if this is a good idea. Some believe that I would be trapping salt water against the insulation which would cause the insulation to degrade. I do not know what material the insulation is and do not expect the manufacturer to divulge that information. If my recommendation would only cause a slight problem over a long period of time, I would go with my recommendation.

So, does salt water attack electrical wire's insulation?

Thanks
CPM
 

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charlie b

Moderator
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Location
Lockport, IL
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Retired Electrical Engineer
I approved this post. But to eliminate concerns that it might comprise advertising, I edited the photo (badly, with apologies) to remove the company name from the detector.
 

PaulMmn

Senior Member
Location
Union, KY, USA
Occupation
EIT - Engineer in Training, Lafayette College
Does the way you've taped the wire affect the angle adjustment of the business end of the detector?
 

Jon456

Senior Member
Location
Colorado
I manufacture products for metal detectors that are used in salt water. I was about to recommend taping (with black electrical tape) an electrical wire to a shaft but have been questioned if this is a good idea. Some believe that I would be trapping salt water against the insulation which would cause the insulation to degrade. I do not know what material the insulation is and do not expect the manufacturer to divulge that information. If my recommendation would only cause a slight problem over a long period of time, I would go with my recommendation.
First, let me say that I doubt the manufacturer of the detector would consider the wire insulation to be a trade secret. It's probably just an off-the-shelf-wire sourced from a wire manufacturer. The bigger question is, will you be able to get a hold of someone at the detector company who knows the answer. But it wouldn't hurt you to try.

That said, I see no reason for residual salt water to degrade the insulation. If the device is approved for use in salt water, then we know the insulation has already been selected for immersion in salt water, so it's good for "some" contact with salt water. And any person using this detector in salt water would be a fool if he didn't rinse off his equipment in fresh water afterwards (just as scuba divers do with their equipment after diving in salt water).

Even if they didn't rinse it off, I can't imagine that the small amount of salt water would cause any chemical degradation of the wire; and it will dry out within a few days. Long-term, I suppose there's the potential for some salt crystals to develop under the tape. Then if the wire is moved frequently, there could be some physical abrasion to the insulation. But even that would likely be negligible over a long period of time because salt crystals are not that strong and the wire isn't able to move much. And the crystals would dissolve the next time the detector was used in water, so there won't be a growing accumulation of crystals.
 

Jon456

Senior Member
Location
Colorado
Personally, I think the tape will cause more problems than it will solve in the long run.

Look at tape under vehicles on trailer wiring. Do you ever see it stay on and NOT get full of salt? In Michigan, anyway.
I agree that the tape shown will probably unravel over time. But this may just be a prototype. There are other products that are more permanent.

The difference between this and a road vehicle is that it's easy to fully rinse the detector with fresh water after use. Even boat trailers that are hosed down after immersion can't get rinsed very well in the wiring harness under the frame.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I manufacture products for metal detectors that are used in salt water. I was about to recommend taping (with black electrical tape) an electrical wire to a shaft but have been questioned if this is a good idea. Some believe that I would be trapping salt water against the insulation which would cause the insulation to degrade. I do not know what material the insulation is and do not expect the manufacturer to divulge that information. If my recommendation would only cause a slight problem over a long period of time, I would go with my recommendation.

So, does salt water attack electrical wire's insulation?

Thanks
CPM

You manufacture products for metal detectors manufactured by others? How does that work?

How did the original manufacturer have the cable attached to the shaft so that you think electrical tape would be better?

-Hal
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Back to the question as asked, no. Salt / salt water is no more corrosive to wire insulation than fresh water. Yes, wire insulation breaks down over time, but the presence of salt is not a factor to worry about in terms of accelerating that process, nor is "trapping" anything against the wire. There are insulated wires running power and communications laying at the bottom of the ocean, with barnacles and coral and all manner of sea life growing on it. The insulation material is not much different than any other insulation material.

Personally, I would slip a single piece of black heat shrink tube over that wire and shaft before attaching it to the head, then shrink it down tight with a heat gun. Less labor than wrapping it with tape and labor costs more than the difference in material cost.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
There are insulated wires running power and communications laying at the bottom of the ocean, with barnacles and coral and all manner of sea life growing on it. The insulation material is not much different than any other insulation material.
I bet it's thicker. :p
 

CPM

Member
A little clarification

A little clarification

The reason for the tape is to reduce the resistance of the shaft sliding through the water (back and forth) while detecting for sometimes up to 8 hours. I did ask the manufacturer about salt but they simply said to wash off the detector with fresh water after each use. The benifit of streamlining is huge, BUT, the tape traps the salt water and is the reason for my basic quesiton. I did not want to recommend the tape if it will damage the wire with the salt. :ashamed1:

More thoughts?

Chuck
 

CPM

Member
Thank You one and all for the help

Thank You one and all for the help

The reason for the tape is to reduce the resistance of the shaft sliding through the water (back and forth) while detecting for sometimes up to 8 hours. I did ask the manufacturer about salt but they simply said to wash off the detector with fresh water after each use. The benifit of streamlining is huge, BUT, the tape traps the salt water and is the reason for my basic quesiton. I did not want to recommend the tape if it will damage the wire with the salt. :ashamed1:

More thoughts?

Chuck

Thank You one and all for the help
Chuck
 
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