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Terminating stranded wires

R

Ryan Evans

Jan 1, 1970
0
Is it ok to terminate stranded wire around the screws of a device?

RE
 
M

Me

Jan 1, 1970
0
NO!


Is it ok to terminate stranded wire around the screws of a device?

RE
 
E

EEng

Jan 1, 1970
0
Is it ok to terminate stranded wire around the screws of a device?

RE
It won't pass UL/CSA/VDE or any other code. Terminate the wire by
crimping/soldering it to a terminal such as a spade or ring connector
then put that to the screw of the device.
 
E

EEng

Jan 1, 1970
0
That would be surprising to U/L.
Reading from the U/L white book ... Receptacles For Attachment Plugs and Plugs
(RTRT)
"Terminals for the wire-binding screw, setscrew, or screw actuated backwiring
clamping types are suitable for use with both solid and stranded building
wire."
Thus it is also OK with the National Electrical Code.

Where do people come up with these urban legends about things that are
"illegal"?

You just confirmed what I said. USE TERMINALS. Nowhere does it say in
any code, including NEC that its okay to simply wrap a wire around a
screw. In ALL cases it specifically mentions using a terminal.
 
E

EEng

Jan 1, 1970
0
"Terminal" in electric code language is anywhere a wire terminates. I assure
you they don't mean a crimped/soldered "ring/spade" terminal.

No sir, you're misinterpreting what the quote you sited says. A
terminal is a specific piece of hardware. There are screws that are
integrated with wire terminals and there are many types but there is a
distinct difference between something that is a terminal, and
something that has been terminated. Example: The wire is terminated
to a terminal. Terminated is to end something. Terminal is what you
terminate something to. In the quote you sited below..........A wire binding screw is a terminal. It is not used for assembling
devices, which is what the OP was asking...."Is it ok to terminate
stranded wire around the screws of a device?" Note the pictures at
the URL listed below. These are terminals that utilize a screw as
part of the terminal structure however they are specifically
designated as terminals in this case board mounted and are absolutely
not used for construction of the device itself.

http://www.zierick.com/connectors/c_binding_post_screw_terminals1.php

Setscrews, clamping screws, etc are also terminals that utilize a
screw as part of the terminal, to make the termination of a wire. As
in barrier strips, the screw clamps the wire to the terminal, but the
wire is at no time simply wrapped around the screw threads. The
closest you might get to that is with the screw actuated backwire
clamp, but note the wire is clamped between two plates, not wrapped
around the screw threads The UL reasoning for this is that the
threads of a screw are sharp enough and there is enough tension, to
cut into the wire thus making it unsafe should the wire be cut
through.

One of the better sites with explanations and pictures to demonstrate,
is http://www.zierick.com

The OP asked about the screws of a device, meaning the screws that
are used to hold the device together. IF the device screw is one of
these types of terminals, then sure, he can use it to terminate his
wire, but in answer to his direct question.... no, it is never okay to
terminate a wire AROUND the screws of a device.

Your quote is excellent, and points specifically to the use of
terminals.
 
EEng said:
No sir, you're misinterpreting what the quote you sited says.

No sir, he is not. It is as he said. To verify this
for yourself, disassemble a UL listed floor or table
lamp. The stranded lamp cord terminates at the socket
terminals, and the stranded conductors are wrapped
around the screws there with no ring/spade/whatever
connectors.


<snip>
 
E

EEng

Jan 1, 1970
0
No sir, he is not. It is as he said. To verify this
for yourself, disassemble a UL listed floor or table
lamp. The stranded lamp cord terminates at the socket
terminals, and the stranded conductors are wrapped
around the screws there with no ring/spade/whatever
connectors.


<snip>

Well, I have three of those, and each are terminated to a wire binding
screw, which is a terminal, not a device screw. That little tab of
metal that is upturned, is to prevent wires from spreading/slipping
out from under the screw head. It's still a terminal.
 
R

Ross Mac

Jan 1, 1970
0
No sir, he is not. It is as he said. To verify this
for yourself, disassemble a UL listed floor or table
lamp. The stranded lamp cord terminates at the socket
terminals, and the stranded conductors are wrapped
around the screws there with no ring/spade/whatever
connectors.


<snip>

In the rare case that I wrap a wire around a screw, I usually strip the wire
extra long, tin it and wrap it clockwise. Consumer devices such as lamps are
a good example of when this might occur. The only problem with tinning a
wire is you need to go back later and re-tighten the connection. Since
tin-lead is soft, just like the aluminum wire put into homes many years ago
and has a tendency to create bad connections....
My two cents...Ross
 
M

Me

Jan 1, 1970
0
EEng is right. If the rest of you would open and read UL's White Book then you would
know for yourself. Reading the NEC does not give you a license to dispense unfounded
advice.


No sir, he is not. It is as he said. To verify this
for yourself, disassemble a UL listed floor or table
lamp. The stranded lamp cord terminates at the socket
terminals, and the stranded conductors are wrapped
around the screws there with no ring/spade/whatever
connectors.


<snip>

Well, I have three of those, and each are terminated to a wire binding
screw, which is a terminal, not a device screw. That little tab of
metal that is upturned, is to prevent wires from spreading/slipping
out from under the screw head. It's still a terminal.
 
E

EEng

Jan 1, 1970
0
news.ops.worldnet.att.net>, [email protected]
says...

The *only* thing I do this with is speaker cable. 16AWG zipcord,
stripped, looped, and tinned. Of course if I were a true
audiophool, worried about the "purity" of the high frequencies,
I'd have used silver solder.


I'll see that and raise you two. I assume it's three raises and
table-stakes here.

No limit
 
EEng said:
Well, I have three of those, and each are terminated to a wire binding
screw, which is a terminal, not a device screw. That little tab of
metal that is upturned, is to prevent wires from spreading/slipping
out from under the screw head. It's still a terminal.

I see that Greg, you and seem to be in agreement. Stranded
wire can be wrapped around a screw. The UL white book does
not prohibit such a connection. The screw must be part of one
of the device's terminals. The difference is that you want
the more complete description "terminal screw" (which I see
as obvious by the question). Do I properly understand you?
 
R

Ross Mac

Jan 1, 1970
0
Keith R. Williams said:
news.ops.worldnet.att.net>, [email protected]
says...

The *only* thing I do this with is speaker cable. 16AWG zipcord,
stripped, looped, and tinned. Of course if I were a true
audiophool, worried about the "purity" of the high frequencies,
I'd have used silver solder.


I'll see that and raise you two. I assume it's three raises and
table-stakes here.
Funny you should say that....That's how I prepared the wires on my speakers
binding posts!....Ross
 
E

EEng

Jan 1, 1970
0
I see that Greg, you and seem to be in agreement. Stranded
wire can be wrapped around a screw. The UL white book does
not prohibit such a connection. The screw must be part of one
of the device's terminals. The difference is that you want
the more complete description "terminal screw" (which I see
as obvious by the question). Do I properly understand you?

Sheesh I've never seen anyone fight so hard to be wrong. A screw
actuated terminal is one in which the screw is used to hold the wire
in place against a constraint that prevents slippage such as a clamp,
an upturned tab, etc. A mere screw used in the assembly of an
enclosure is none of these and cannot be used to terminate a wire
merely by wrapping it around the threads of said screw. UL is very
specific about using the terminology TERMINAL. If it had meant screw
by itself, it would have said screw by itself.
 
R

Ross Mac

Jan 1, 1970
0
EEng said:
Sheesh I've never seen anyone fight so hard to be wrong. A screw
actuated terminal is one in which the screw is used to hold the wire
in place against a constraint that prevents slippage such as a clamp,
an upturned tab, etc. A mere screw used in the assembly of an
enclosure is none of these and cannot be used to terminate a wire
merely by wrapping it around the threads of said screw. UL is very
specific about using the terminology TERMINAL. If it had meant screw
by itself, it would have said screw by itself.

I assume we are talking about a barrier strip???
Just curious...... :>)
 
E

EEng

Jan 1, 1970
0
It is very clear nobody here who thinks a "terminal" is anything other than the
screw on the side of a device has never worked in a commercial electrical
project where they pull a lot of stranded wire through raceway systems.
I suppose the hundreds of buildings I have inspected are ALL wrong but it would
be a huge surprise the the electricians and other inspectors who work there.
The trick is simply craftsmanship. You tightly twist the wire and properly
tighten the screw.
If you want to crimp on a spade terminal with the correct tool and use that or
tin the wire, by all means do so but you will never see either of them on a
commercial wireman's tool cart.

Fine, believe what you want. If you can't distinguish between a
proper terminal and a device screw then more's the pity, and just
because it is common practice to save money and time by using a
standard screw AS a terminal when it is clearly not, neither by design
or by code, doesn't make it right. Between the political BS and
bottom line dollar, more is done incorrectly on purpose, with
authorization than is done by the book. Clearly, those who believe
that a device screw is a terminal, have never worked on anything DOD.

End of topic out of sheer frustration with those who demand the right
to do it wrong.
 
R

Ross Mac

Jan 1, 1970
0
Greg said:
It is very clear nobody here who thinks a "terminal" is anything other than the
screw on the side of a device has never worked in a commercial electrical
project where they pull a lot of stranded wire through raceway systems.
I suppose the hundreds of buildings I have inspected are ALL wrong but it would
be a huge surprise the the electricians and other inspectors who work there.
The trick is simply craftsmanship. You tightly twist the wire and properly
tighten the screw.
If you want to crimp on a spade terminal with the correct tool and use that or
tin the wire, by all means do so but you will never see either of them on a
commercial wireman's tool cart.

It's a little difficult to tell, by the limited information, exactly what
the OP was up to. He doesn't mention if it's an industrial or household
setting or even if he is speaking of a barrier strip. The commercial wiring
folks that I have used, usually used crimp connectors on barrier strips or
just pushed the strands into a terminal strip and tightened the screw. The
key here is that I hired these folks and am not the code expert.....
Take care.....:>) ...Ross
 
E

EEng

Jan 1, 1970
0
You can say it is just being cheap but it is NEC code and it is within the U/L
listing for the standard switches and receptacles used in residential or
commercial wiring. Just because that is not how people do it at DoD does not
mean it is not legal. Those are the guys who buy $800 hammers.


I suggest you take a much closer look at those switches and
receptacles. Where the wire goes, there is a small upturned tab. It
might look like just a screw but its not...its a screw actuated
terminal because of that little tab, whose sole function is to prevent
the wire from slipping out from under the head of the screw. That's
why they're usually so hard to put a wire to, because that tab gets in
the way. Also consider that UL, NEC and other codes are written for
one purpose ONLY. It is not for standardization, it is to satisfy
SAFETY requirements that would otherwise result in lawsuits, etc.

All the manufacturing codes, installation codes, etc, are written for
safety. Now, do you honestly believe that with all the safety issues
addressed in these codes, that they would say its okay to simply wrap
a wire around just any old screw? THINK. It's obvious you don't
recognize a terminal when you see one if you believe that the screw on
receptacles and switches is just a screw.
 
R

Ross Mac

Jan 1, 1970
0
EEng said:
I suggest you take a much closer look at those switches and
receptacles. Where the wire goes, there is a small upturned tab. It
might look like just a screw but its not...its a screw actuated
terminal because of that little tab, whose sole function is to prevent
the wire from slipping out from under the head of the screw. That's
why they're usually so hard to put a wire to, because that tab gets in
the way. Also consider that UL, NEC and other codes are written for
one purpose ONLY. It is not for standardization, it is to satisfy
SAFETY requirements that would otherwise result in lawsuits, etc.

All the manufacturing codes, installation codes, etc, are written for
safety. Now, do you honestly believe that with all the safety issues
addressed in these codes, that they would say its okay to simply wrap
a wire around just any old screw? THINK. It's obvious you don't
recognize a terminal when you see one if you believe that the screw on
receptacles and switches is just a screw.

Isn't that for solid wire as opposed to stranded?
 
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