corrosion on neutral

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parttimer

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Service call this week. The HO had problems with corrosion on the neutal lug and neutral bus. The journeyman I was with had us replace the main neutral conductor and panel lug, clean the bus and trim wires and use bear grease at all lugs and connections. The panel looks to be maybe 10 years old (upgraded from fuse type apparently), is located in FL about 2 blocks from intercoastal.

I understand that AC should not corrode. The issue is that I did not see that we did anything to find or correct the problem. Being apprentice, I think that we only did half the job? Shouldn't we have been looking for some stray dc somewhere or is corrosion near salt water and high humidity common? If it is common why is bear grease not required on all installs and then even all connections of dissimilar metals? I know that the meters seem installed with bear grease always, as well as breakers. I have also seen corrosion in neutrals of ceiling fans, lights and other devices here and it seems the actual cause is not being repaired?
 
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parttimer

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AC not corrode

AC not corrode

I have only been a manufacturing engineer and quality engineer, am now retired to FL and work with 3 different kinds of contractors part time (GC, EC and soil sampling). Keeps me active and pays the bills. My experience has been that dc with dis-similar metals induces corrosion by electrolytic action. I have never seen ac do this without other influence. Plating shops use ac to clean metals and remove impurities (in solution of course). I am only asking if anyone knows what should be looked at as a root cause as it does NOT seem normal and I have seen it more than once on service calls. It doesn't seem that replacing or trimming a wire is enough to solve the issue.
The "journeyman" I am working with I do not trust to have all the knowledge needed (this is FL not CA or NY!)

Since noone seems to care to address the question I will just ask my boss or maybe my old boss (EC) in CA.

Thanks
 
tom baker

tom baker

First Chief Moderator
Staff member
Location
Bremerton, Washington
Here where we are near the salt water, I commonly see aluminum lugs corroded when connected to a copper wire, after being installed for a few years.
I always use copper and stainless steel hardware.
 
sparky_magoo

sparky_magoo

Senior Member
Location
Reno
parttimer said:
I have only been a manufacturing engineer and quality engineer, am now retired to FL and work with 3 different kinds of contractors part time (GC, EC and soil sampling). Keeps me active and pays the bills. My experience has been that dc with dis-similar metals induces corrosion by electrolytic action. I have never seen ac do this without other influence. Plating shops use ac to clean metals and remove impurities (in solution of course). I am only asking if anyone knows what should be looked at as a root cause as it does NOT seem normal and I have seen it more than once on service calls. It doesn't seem that replacing or trimming a wire is enough to solve the issue.
The "journeyman" I am working with I do not trust to have all the knowledge needed (this is FL not CA or NY!)

Since noone seems to care to address the question I will just ask my boss or maybe my old boss (EC) in CA.

Thanks
Click to expand...

The CA journeyman test seems to have been written at a fourth grade level. Where did that comment come from? Even I did well on the CA test.:D
 
sparky_magoo

sparky_magoo

Senior Member
Location
Reno
Much of my service work is on the coast. Service upgrades to replace corroded panels are a staple. I recently replaced a 400 amp 240V service in a trailer park. The nuetral main lug had corroded entirely away. Quite a common problem around here.
 
chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
sparky_magoo said:
The CA journeyman test seems to have been written at a fourth grade level. Where did that comment come from? Even I did well on the CA test.:D
Click to expand...

I got a 90 on Miami-Dades test and 92 on Browards. I am well aware the state of the industry here leaves alot to be desired but please understand that some of us still go out of our way to try to make a difference.
 
R

RUWired

Senior Member
Location
Pa.
parttimer said:
Service call this week. The HO had problems with corrosion on the neutal lug and neutral bus. and it seems the actual cause is not being repaired?
Click to expand...

Part timer,Corrision on the neutral lug and bus and terminal strip is a classic example of a water leak dripping down through the inside of the cable.Check for proper drip loop, and duct seal on the top of the service equipment.sometimes the cable is so badly worn, the water seeps through the outer jacket.Of course if this an underground service,you have other issues.
Rick
 
cschmid

cschmid

Senior Member
Location
Northern cold country
so what type of wire? what type of feed over head or under ground? and corrosion is an issue on meter and main lugs..Is the panel inside or outside? there are a variety of issue that can affect corrosion like temp, weather, humidity, ect.. and even improper maintenance of the panel..like not regularly torquing the lugs to insure proper contact..even the local POCO does that here..many reasons why one is regular outside temp changes, it can be 40 below zero and get to 30 above zero that is 70 degree temp change..just like having 110 during the day and 40 degrees at night...
 
P

parttimer

Member
Thanks, this did help

Thanks, this did help

Being from the SF bay area originally there may have been high salt content near the water but low humidity elsewhere so I never saw this there. This is all gonna be new to me as the humidity and salt here is totally different.

RU wired- If I recall it was standard weatherhead below the eaves (kinda different) and had sufficient loop ( I need to ask about this in FL as rain travels every direction here!). Exterior panel standard mount. You did give me some things to think of next call though. Cu conductor to Alum lug. the corrosion was behind the meter and in the main pnl both, did not seem to be on the neutral drop nearly as bad.

Mgd- that link was excellent. It did look as if they made a "worst case" accelerated time test and that copper to copper is the ONLY way to go! The worst sample they showed Al to Cu conductor was similar to what I saw. Hte main thing I noticed was a statement that damage to the zinc coating on the lug will cause failures.

To all,
In CA there are many Union Journeymen. I hate unions overall, but the knowledge they require for journeymen if properly managed does outflow from the union to the trades in general. I think this may benefit many areas of the nation a lot. Here in FL I have just seen too much shoddy work I guess. The old work here from the 50's was excellent overall though.

If I am to learn, I want to learn from the best! Can't go wrong with that.
 
cowboyjwc

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Are you sure that it was an aluminum lug and not just a tinned copper one?

We don't have a lot of humidity here, but closer to the coast where sparky_magoo is, it is a lot more common to see the type of corrision that you described, but, and I tend to throw a lot of buts in, it could have been as simple as a loose lug.

We have panels here that are 40+ years old and there's not a thing wrong with them other than simple aging.
 
P

parttimer

Member
I have

I have

No-ox in my bucket pouch now. I will not fail to use it wherever it seems likely to be needed.

The conductor was well compressed and there was ot much else that could have happened. It of course could have been tinned copper lug but we didn't remove it, just repaird the connection. I learned a lot here already.

THanks all!

Learn from the best!
 
stalllingselectric

stalllingselectric

Member
Location
California
most aluminum that has been introduced to Salt laden air will be affected
as far as the repair, just stripping back the wire may not be enuff, the condition of the Lug should be verified
 
C

cosmo

Member
Location
Virginia
I have found that here on the coast of virginia that the salt air will cause the aluminum conductors to corrode if they are exposed regularly. On some boat docks where aluminum SER was used I have seen the un-insulated conductor have a white powdery coat.
 
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