Zinc GRD. clamps vs. bronze GRD. clamps
- Thread starter zappy
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IMO, you should choose to minimize galvanic action.
The clamps you are calling zinc are just plated with or hot-dipped in zinc (i.e. galvanized). The base metal is likely iron or steel.
brian john
Senior Member
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- Kilmarnock, Va
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- Retired after 52 years in the trade.
How much of a savings? How many are you installing?
bphgravity
Senior Member
- Location
- Florida
The Zinc variety may NOT be suitable for use in direct burial or on rebar applications, whereas the Bronze varieties usually are.
Ground clamps
Ground clamps
Listed Direct Burial ground clamps are mainly bronze where as 18" above grade pipe clamps are available in Zinc plated clamps. The UL White Book mentions direct burial clamps as being marked DB.
Ground clamps
Listed Direct Burial ground clamps are mainly bronze where as 18" above grade pipe clamps are available in Zinc plated clamps. The UL White Book mentions direct burial clamps as being marked DB.
I don't know what they're made of, but some of the "zinc" grounding clamps that I see are really light....too light to be steel or iron.
Leads me to believe that they are 100% Zinc.
Could be wrong though.
steve
I don't know what they're made of, but some of the "zinc" grounding clamps that I see are really light....too light to be steel or iron.
Leads me to believe that they are 100% Zinc.
Could be wrong though.
steve
Perhaps there are zinc only clamps. Perhaps, and quite likely the light, inexpensive ones are made of the so-called pot metal but they can be called zinc because it is the alloy element of highest content.
When I started to write my comment I had "are likely to be" iron or steel, and even then I should have wrote "the better ones"...
...but somehow neither made it into my now unedittable post
M. D.
Senior Member
Some measure of time ago ,..there was a discussion in regard to the bonding of black iron pipe in relation to the CSST lightning issue,. ... the only clamp I found that specifically listed black iron pipe was a zinc alloy pipe clamp,.. just thought I'd share that little tid bit
LJSMITH1
Senior Member
- Location
- Stratford, CT
Perhaps there are zinc only clamps. Perhaps, and quite likely the light, inexpensive ones are made of the so-called pot metal but they can be called zinc because it is the alloy element of highest content.
When I started to write my comment I had "are likely to be" iron or steel, and even then I should have wrote "the better ones"...
...but somehow neither made it into my now unedittable post
:roll: "Pot Metal"? If a clamp or fitting has a UL or CSA bug on it, it is highly unlikely that it has been made of an inferior zinc alloy. The main reason is that it would never pass the UL tests to become listed in the first place. My point is not all zinc die castings are created equally.
Pot metal is typically an alloy of Tin, Copper, Zinc and Lead. Most Electrical fittings made of Die Cast Zinc is a special grade of "Zamak" - not pot metal. We use an ASTM B86 certified grade of Zamak 7, which helps us guarantee the production quality of our products. However, you could still use the best raw materials on the planet, and if the manufacturing process is not controlled, there will be quality problems such as hidden porosity, brittleness, or excessive flash. Unfortunately, many competitors have offshored these products/processes and are less concerned about the raw material quality and resulting manufacturing quality. This has absolutely given zinc die castings a "black eye", and continues to be a problem for many electricians in the field.
With regards to the DC zinc clamps, if they are listed then they meet the same spec as the Bronze versions - UL467. The only exception is that they cannot be directly buried. In many cases they are absolutely suitable for indoor/dry applications, and thats what they are listed for, and are typically slightly less $ than the Bronze version.
UL467 is mainly concerned with the bonding and current carrying capability of the clamp. There is no separate listing for black pipe, copper pipe, rebar, or brass gass fittings. However, there is a proposal to have a separate fit test to list a clamp suitable for use on the brass CSST gas fittings. As far as I know, the UL specification has not yet been revised.
So, if a clamp is listed to UL467, it will work in most applications where it fits properly, can be tightened sufficiently, and has conductivity with the item its clamped on (i.e. scrape off that paint!).
While I give creedance to your comments, I do consider them somewhat biased towards the products you take part in, either directly or indirectly as a manufacturing representative. It is not my intent to berate quality manufactured goods. However, you have no control over what products do make it to market with or without UL approval.
As for what I call "pot metal", I will stand by the general description given by wikipedia:
c2500
Senior Member
- Location
- South Carolina
I don't know what they're made of, but some of the "zinc" grounding clamps that I see are really light....too light to be steel or iron.
Leads me to believe that they are 100% Zinc.
Could be wrong though.
steve
I looked it up...diecast is usually zinc and aluminum. Though I now see a much more indepth explaination was done prior to my posting. (Must remember to read through entire post before posting)
c2500
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LJSMITH1
Senior Member
- Location
- Stratford, CT
You are right, I don't have control of any other product aside from our own. I am a manufacturer, and keenly tuned into the competition and industry we are in. I also have absolute control over what product of ours makes it to market with or without a UL listing. If there is an applicable UL listing for a product, we do everything we can to make sure we get it.
All I am saying is that "if" a die cast zinc product has a UL/CSA/ETL bug on it, it will have passed the required listing tests stated in the applicable UL specification. If the product was made with inferior Zinc alloys (like a pot metal), it would not have passed the more severe evaluations such as pull or ground fault current tests. These tests require the best alloys for the job and they are typically the Zamak grade. Did you know that a 1/2" EMT fitting (setscrew or compression) needs to hold a 300 lb pull for 5 minutes? Or that the same fitting needs to handle a Ground Fault Current of 1,180A for 4 seconds without arcing or damage? Substandard materials could not handle these kinds of tests.
The real issue, which many electricians might experience, is the inconsistent quality and poor design of many fittings products out there. How many times have you cranked down a zinc locknut only to have it jump a thread? Or, tightened a setscrew on a zinc fitting only to see the boss crack, have the screw strip, or have the head of the screw snap off? These are not necessarily bad materials, but rather poor design and/or quality control. They may have passed UL testing in a controlled environment where torque wrenches are used and very specific test procedures are followed. However, in the field, they may be marginal - and this is due to quality control and initial design.
I really try not to be biased anywhere on here and in other forums, and only report my experiences from another point of view. I am sorry if my comments come across as biased, but I am only trying to relay facts and not opinions.
On a lighter note......Speaking of "Pot Metal".
Anyone remember the "pot metal" door latches that were used on American Cars in the 40's and 50's?
I was told it was "pot metal" by my grandfather who was a machinist in a foundry.
Seriously, all that kept the doors closed on these cars was a piece of cheap alloy.
It's no wonder that the doors always came open when the car was involved in a crash or roll over.
As a boy, I used to remove the latch castings from the door posts of these old cars, and melt them down to make fishing sinkers.
A hot wood fire and a tin can was all that was needed.
Off topic, I know, but maybe a little interesting.
steve
Anyone remember the "pot metal" door latches that were used on American Cars in the 40's and 50's?
I was told it was "pot metal" by my grandfather who was a machinist in a foundry.
Seriously, all that kept the doors closed on these cars was a piece of cheap alloy.
It's no wonder that the doors always came open when the car was involved in a crash or roll over.
As a boy, I used to remove the latch castings from the door posts of these old cars, and melt them down to make fishing sinkers.
A hot wood fire and a tin can was all that was needed.
Off topic, I know, but maybe a little interesting.
steve
LJSMITH1
Senior Member
- Location
- Stratford, CT
Sure, that's very true. Most of that alloy had lead in it, which made it very easy to cast. The alloy was also 'strong enough' for whatever safety requirements were out there at the time.
Die casting is an excellent metal forming process as it can produce "net shape' parts requiring very little machining. Many automotive components are die cast aluminum alloy (i.e. transmission housings, differential housings, suspension components, etc.).
Nowadays, between the NHTSA and Auto manufacturers, there are very complicated and advanced safety features that were not even a thought back in the 40's. Frames are obsolete and are replaced by uni-body constructions. Seatbelts and safety glass are standard.
We may moan about how much a car costs nowadays, but compare all the features we now get as standard items over what was available 40 years ago...there is no question we are getting more for our money.
Die casting is an excellent metal forming process as it can produce "net shape' parts requiring very little machining. Many automotive components are die cast aluminum alloy (i.e. transmission housings, differential housings, suspension components, etc.).
Nowadays, between the NHTSA and Auto manufacturers, there are very complicated and advanced safety features that were not even a thought back in the 40's. Frames are obsolete and are replaced by uni-body constructions. Seatbelts and safety glass are standard.
We may moan about how much a car costs nowadays, but compare all the features we now get as standard items over what was available 40 years ago...there is no question we are getting more for our money.
I don't know the opinions of others in particular, but in my mind, having a NRTL bug on the product does not necessarily mean it is a quality product. All it means is that the part passed certain tests which were implemented to safeguard practicable usage of the product as intended. To me, that may guarantee of a certain level of quality... but yet could be far from the best quality
But then we enter into the realm of economics.... and a whole new light is cast (pun intended
) on the subject
LJSMITH1
Senior Member
- Location
- Stratford, CT
I don't know the opinions of others in particular, but in my mind, having a NRTL bug on the product does not necessarily mean it is a quality product. All it means is that the part passed certain tests which were implemented to safeguard practicable usage of the product as intended. To me, that may guarantee of a certain level of quality... but yet could be far from the best quality
But then we enter into the realm of economics.... and a whole new light is cast (pun intended
:grin: Yes..Quality and a Listing are two separate, but related things. What has driven quality to the lowest common denominator is the price. Constant downward price pressure is not only taking these products overseas, but indirectly reducing consistency of the quality. Unless a company has offshore, on-site quality inspection, many companies don't bother with any inspection until the material winds up in the hands of the customer. Sad but true..
The great thing is that we have absolute control of what we design and produce, which includes quality. On the things we purchase and resell, we try our best to "influence" the quality to be as good or better than our own. In most cases we succeed - at a price. Shipments of products may be rejected at the dock, and we may find ourselves out of stock (a bad thing in our industry). Its a constant, behind the scenes battle that our customer hopefully never gets to see.
Doug S.
Senior Member
- Location
- West Michigan
Zamak... I can't get over that one. I'm fairly young, but thought Zamak had gone the route of the "pot metal". Show's what I know.
As far as the op goes... Personally I prefer bronze, if it's a decent alloy it should out last all parties present, but now that I know there's Zamak to be had I may be wooed.
Thanks,
Doug ( A wanna be, hobby machinist, too. )
As far as the op goes... Personally I prefer bronze, if it's a decent alloy it should out last all parties present, but now that I know there's Zamak to be had I may be wooed.
Thanks,
Doug ( A wanna be, hobby machinist, too. )
LJSMITH1
Senior Member
- Location
- Stratford, CT
Zamak (ZA) is a zinc alloy blend trademark. It actually means "Zinc-Aluminum" and was developed in Germany in the late 1920's. It 'sounds cheap' to some folks, but it encompasses at least 5 different alloys - each with slightly different properties. The critical importance of the Zamak alloy is the high purity zinc that is required (99.99% pure or better). If that level of pure zinc is not in the alloy, it is not Zamak - and probably approaches the quality of 'pot metal'. Real Pot metal has no requirement for purity or exact composition. This is why it has such a bad reputation for poor strength, consistency, or longevity. Unfortunately, 'any' die cast metal has been grouped into the 'pot metal' terminology. It could be die cast magnesium, aluminum, or titanium, but its all pot metal to some folks.
High quality die castings require a certified alloy to be consistently free of defects like porosity, and to maintain specific properties like tensile strength or ductility. ASTM B86 is the industry specification for Zamak 7 (ZA-7). If the alloy meets that standard, you will be assured you are receiving the highest quality and performing zinc-aluminum alloy available.
Of course, this all goes out the window if the manufacturing process is not controlled or monitored. This is where many products fail due to quality or performance issues caused by poor die casting control.
High quality die castings require a certified alloy to be consistently free of defects like porosity, and to maintain specific properties like tensile strength or ductility. ASTM B86 is the industry specification for Zamak 7 (ZA-7). If the alloy meets that standard, you will be assured you are receiving the highest quality and performing zinc-aluminum alloy available.
Of course, this all goes out the window if the manufacturing process is not controlled or monitored. This is where many products fail due to quality or performance issues caused by poor die casting control.
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