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question about solid conductor, solid wires in detonator circuit?

C

chemstu

Jan 1, 1970
0
Does anyone know why commercial detonators have small gage solid
conductor leg wires? And why only solid conductor wire is recommended
in a blast circuit?

I have an idea, but I cannot be sure. I have some electrical/physics
knowledge, and I understand that both solid wire and stranded wire have
advantages, but I do not understand the details as to the why solid
wires are chosen in commercial caps. There is so much unreliable info
on the web about comparisons between solid and stranded wire -
especially as it pertains to the home audio and data communication
industries. Some of the info is contradictory. It is hard to sift
through it all.

Here is what I know on the subject: The DC current carrying capacity
between solid and stranded wire is negligible in most cases.

I understand that skin effect allows higher frequency AC to travel
easier through stranded wire than it does through solid wire because of
the increased surface area due to multiple strands. Although, at least
a high frequencies, I believe that the benefit gained from skin effect
is in turn lessened by the slight inductances that can set up between
individual strands. Then there is the matter of corrosion throughout a
stranded wire on the surface the strands or between strands that grows
with time. No doubt these inductances etc. degrade signals - I am
assuming that that is the main reason that CAT5/6 is solid conductor.
It seems that stranded wire is only advised for CAT 5/6 when patching
and where physical stress is expected on the wire.

I am aware that DC voltage is used to fire a detonator. However, at
least in case of an EBW, foil, etc., the current pulse rise times are
so fast that, the waveform appears as critical as the current and
voltage delivered. High frequency? at least for one pulse?

Then there is the notion of physical durability of wire. In cases of
physical usage, stranded wire outperforms solid sire due to its
flexibility. However a detonator is not a repeated use item.

I am sure that stranded wire will work in a blast circuit in the real
world. There are plenty of sites for homebrew detonators that instruct
the maker to use stranded wire. But, I am specifically speaking of the
sole use solid wire in commercial caps. I have read that article about
the failure of the IED that Ted K made and tried to use. Apparently an
EOD investigator concluded that had he used solid wire the IED would
have detonated. So, solid wire appears critical doesn't it.

Theories -

Stranded wire - reasons to use:
1. flexibility?
2. skin effect allows for faster rise time in detonation pulse?

Solid conductor wire - reasons to use
1. inflexible, possibly wires assist in physically holding the
detonator in place?
2. inflexible, leg wires are not expected to be bent many times
3. lack of skin effect not benefit not a problem - likely true with
slower caps
4. lack of skin effect not benefit not a problem - waveform not
critical affected for EBW etc..
5. broken wire can be discovered easier than with stranded before use
6. less possibility of corrosion buildup as between strands in stranded
wire
7. less possibility of inducing current into stranded wire broken
strands from ext RF source
8. more reliable connection when wires are twisted?

I hope I am not to far off in my theories. Please feel free to comment
on my theories and to any specific relevance to an explanation as to
why solid wire is chosen in commercial detonators. Any other info is
appreciated.

THX, EC
 
P

Pooh Bear

Jan 1, 1970
0
chemstu said:
Does anyone know why commercial detonators have small gage solid
conductor leg wires? And why only solid conductor wire is recommended
in a blast circuit?

I have an idea, but I cannot be sure. I have some electrical/physics
knowledge, and I understand that both solid wire and stranded wire have
advantages,

Stranded is flexible ( very important where needed ). Solid is probably cheaper
to make but'll fracture if flexed repeatedly ( hence not used for patch cords ).

Skin effect doesn't apply to stranded cable per the individual conductor size as
the strands aren't insulated from each other.

I suspect in your case maybe solid wire is simply easier to twist / splice onto
the detonation cable.

Graham
 
R

Ross Herbert

Jan 1, 1970
0
Does anyone know why commercial detonators have small gage solid
conductor leg wires? And why only solid conductor wire is recommended
in a blast circuit?

I have an idea, but I cannot be sure. I have some electrical/physics
knowledge, and I understand that both solid wire and stranded wire have
advantages, but I do not understand the details as to the why solid
wires are chosen in commercial caps. There is so much unreliable info
on the web about comparisons between solid and stranded wire -
especially as it pertains to the home audio and data communication
industries. Some of the info is contradictory. It is hard to sift
through it all.

Here is what I know on the subject: The DC current carrying capacity
between solid and stranded wire is negligible in most cases.

I understand that skin effect allows higher frequency AC to travel
easier through stranded wire than it does through solid wire because of
the increased surface area due to multiple strands. Although, at least
a high frequencies, I believe that the benefit gained from skin effect
is in turn lessened by the slight inductances that can set up between
individual strands. Then there is the matter of corrosion throughout a
stranded wire on the surface the strands or between strands that grows
with time. No doubt these inductances etc. degrade signals - I am
assuming that that is the main reason that CAT5/6 is solid conductor.
It seems that stranded wire is only advised for CAT 5/6 when patching
and where physical stress is expected on the wire.

I am aware that DC voltage is used to fire a detonator. However, at
least in case of an EBW, foil, etc., the current pulse rise times are
so fast that, the waveform appears as critical as the current and
voltage delivered. High frequency? at least for one pulse?

Then there is the notion of physical durability of wire. In cases of
physical usage, stranded wire outperforms solid sire due to its
flexibility. However a detonator is not a repeated use item.

I am sure that stranded wire will work in a blast circuit in the real
world. There are plenty of sites for homebrew detonators that instruct
the maker to use stranded wire. But, I am specifically speaking of the
sole use solid wire in commercial caps. I have read that article about
the failure of the IED that Ted K made and tried to use. Apparently an
EOD investigator concluded that had he used solid wire the IED would
have detonated. So, solid wire appears critical doesn't it.

Theories -

Stranded wire - reasons to use:
1. flexibility?
2. skin effect allows for faster rise time in detonation pulse?

Solid conductor wire - reasons to use
1. inflexible, possibly wires assist in physically holding the
detonator in place?
2. inflexible, leg wires are not expected to be bent many times
3. lack of skin effect not benefit not a problem - likely true with
slower caps
4. lack of skin effect not benefit not a problem - waveform not
critical affected for EBW etc..
5. broken wire can be discovered easier than with stranded before use
6. less possibility of corrosion buildup as between strands in stranded
wire
7. less possibility of inducing current into stranded wire broken
strands from ext RF source
8. more reliable connection when wires are twisted?

I hope I am not to far off in my theories. Please feel free to comment
on my theories and to any specific relevance to an explanation as to
why solid wire is chosen in commercial detonators. Any other info is
appreciated.

THX, EC

There are no "technical" reasons why solid conductor is used in
preference to stranded conductors on electric detonators.

I think you will find that it is all to do with convenience. Back in
the 1950's when I first used electric detonators they had solid
conductors and in those days they were insulated with waxed cotton and
not pvc. Wire stripping tools were not all that common even in the
telecommunications industry where solid wire was insulated with enamel
and waxed cotton was used, and it would have been fairly difficult to
keep any stripping tool in a serviceable condition in wet and dirty
conditions, so it was easier if no tool was required. When the shot
firer in the field had grimy hands and there was crap everywhere, the
easiest way to bare the end of the wire for joining to the firing
cable was to use your teeth. Not so easy with stranded conductors.
Apart from being cheaper to produce it was also far easier to perform
a simple twist joint with solid conductors than with stranded
conductors.
 
J

John Larkin

Jan 1, 1970
0
Does anyone know why commercial detonators have small gage solid
conductor leg wires? And why only solid conductor wire is recommended
in a blast circuit?

I have an idea, but I cannot be sure. I have some electrical/physics
knowledge, and I understand that both solid wire and stranded wire have
advantages, but I do not understand the details as to the why solid
wires are chosen in commercial caps. There is so much unreliable info
on the web about comparisons between solid and stranded wire -
especially as it pertains to the home audio and data communication
industries. Some of the info is contradictory. It is hard to sift
through it all.

Here is what I know on the subject: The DC current carrying capacity
between solid and stranded wire is negligible in most cases.

I understand that skin effect allows higher frequency AC to travel
easier through stranded wire than it does through solid wire because of
the increased surface area due to multiple strands. Although, at least
a high frequencies, I believe that the benefit gained from skin effect
is in turn lessened by the slight inductances that can set up between
individual strands. Then there is the matter of corrosion throughout a
stranded wire on the surface the strands or between strands that grows
with time. No doubt these inductances etc. degrade signals - I am
assuming that that is the main reason that CAT5/6 is solid conductor.
It seems that stranded wire is only advised for CAT 5/6 when patching
and where physical stress is expected on the wire.

I am aware that DC voltage is used to fire a detonator. However, at
least in case of an EBW, foil, etc., the current pulse rise times are
so fast that, the waveform appears as critical as the current and
voltage delivered. High frequency? at least for one pulse?

Then there is the notion of physical durability of wire. In cases of
physical usage, stranded wire outperforms solid sire due to its
flexibility. However a detonator is not a repeated use item.

I am sure that stranded wire will work in a blast circuit in the real
world. There are plenty of sites for homebrew detonators that instruct
the maker to use stranded wire. But, I am specifically speaking of the
sole use solid wire in commercial caps. I have read that article about
the failure of the IED that Ted K made and tried to use. Apparently an
EOD investigator concluded that had he used solid wire the IED would
have detonated. So, solid wire appears critical doesn't it.

Theories -

Stranded wire - reasons to use:
1. flexibility?
2. skin effect allows for faster rise time in detonation pulse?

Solid conductor wire - reasons to use
1. inflexible, possibly wires assist in physically holding the
detonator in place?
2. inflexible, leg wires are not expected to be bent many times
3. lack of skin effect not benefit not a problem - likely true with
slower caps
4. lack of skin effect not benefit not a problem - waveform not
critical affected for EBW etc..
5. broken wire can be discovered easier than with stranded before use
6. less possibility of corrosion buildup as between strands in stranded
wire
7. less possibility of inducing current into stranded wire broken
strands from ext RF source
8. more reliable connection when wires are twisted?

I hope I am not to far off in my theories. Please feel free to comment
on my theories and to any specific relevance to an explanation as to
why solid wire is chosen in commercial detonators. Any other info is
appreciated.

THX, EC


Maybe because they spot-weld the tiny ignition link to the lead wires,
and it's hard to weld to stranded wire.

John
 
F

Fred Bloggs

Jan 1, 1970
0
chemstu said:
Does anyone know why commercial detonators have small gage solid
conductor leg wires?

Probably a combination of historical and manufacturing concerns, with
solid wire more amenable to the various lineman's splice techniques,
cheaper, more suitable for the types of attachment to the heater wire
internally- originally a crimp, simpler moisture resistant insulation +
wire manufacture- it is important that moisture not wick into the
interior of the cap and dampen the primer, and no requirement for
fatigue resistance to continual flexing.
And why only solid conductor wire is recommended
in a blast circuit?

I'm not sure that is the case- may have derived from the military
practice of using readily available "field telephone wire."
 
M

me

Jan 1, 1970
0
Fred Bloggs said:
Probably a combination of historical and manufacturing concerns, with
solid wire more amenable to the various lineman's splice techniques,
cheaper, more suitable for the types of attachment to the heater wire
internally- originally a crimp, simpler moisture resistant insulation +
wire manufacture- it is important that moisture not wick into the
interior of the cap and dampen the primer, and no requirement for
fatigue resistance to continual flexing.


I'm not sure that is the case- may have derived from the military
practice of using readily available "field telephone wire."


"field telephone wire" is stranded. 3 steel and 4 copper wires (as near
as I can recall).
 
R

Reg Edwards

Jan 1, 1970
0
The answer is staring you all in the face.
Solid wire is cheaper than stranded wire.
 
C

chemstu

Jan 1, 1970
0
Well, thanks for the ideas everyone, I am sure everyone can see that
there are different ideas out there - I posted this question with a
couple of other engineering/physics groups - same result.

I am thinking that the idea of the lack of integrity/reliability of the
individual strands in stranded wire, which could result in insufficient
current carrying ability and might not allow detonators to function
properly, seems like a good answer as far as the functioning of the
wires. I also see the logic in the other ideas about ease of handling.

However, as you can read on the web, various states i.e. PA, NJ etc.
not only require by law that detonators have solid leg wires - but
that all wiring in the blast circuit be solid conductor also.

This leads me to again see the logic of the idea the physical integrity
of the wiring - which in turn relates to the integrity current
capacity - is seen as critical enough to induce both, the manufacturers
to assemble detonators with solid wires, and individual states to pass
laws requiring that solid wiring be used for detonators and detonator
circuits.

PS I am glad for the replies and that a couple of people
actually found the question intriguing, I at first thought that no-one
would reply.

THX EC
 
R

Ross Herbert

Jan 1, 1970
0
Well, thanks for the ideas everyone, I am sure everyone can see that
there are different ideas out there - I posted this question with a
couple of other engineering/physics groups - same result.

I am thinking that the idea of the lack of integrity/reliability of the
individual strands in stranded wire, which could result in insufficient
current carrying ability and might not allow detonators to function
properly, seems like a good answer as far as the functioning of the
wires. I also see the logic in the other ideas about ease of handling.

However, as you can read on the web, various states i.e. PA, NJ etc.
not only require by law that detonators have solid leg wires - but
that all wiring in the blast circuit be solid conductor also.

There are many GOOD reasons NOT to use stranded conductors but these
are related to practical methods of ensuring physical integrity which
thereby ensures electrical integrity as much as possible.

If stranded conductors were used imagine the problems which could
result if a single strand had escaped the joining procedure and was
intermittently shorting the detonator leads. This problem cannot occur
using solid conductors.

The various states you mention probably include the solid conductor
requirement in their law just to prevent cowboys from using stranded
conductors for no other reason than "there was nothing stated in the
regulations not to do so". Assuming a shorted detonator due to an
escaped strand where stranded conductors were used, and someone was
injured as a result of a misfire after they went to check on why the
detonator didn't work, there would be a legal "out" for a
supervisor/employer because the regulations did not specifically
outlaw the use of stranded conductors.
 
F

Fred Bloggs

Jan 1, 1970
0
me said:
"field telephone wire" is stranded. 3 steel and 4 copper wires (as near
as I can recall).

It is WD-1/TT MIL-C-13294 which looks to be superseded by MIL-C-49104
wire. There is a distinction to be made between "stranded" and
"flexible" wire- strictly speaking.
 
F

Fred Bloggs

Jan 1, 1970
0
Well, thanks for the ideas everyone, I am sure everyone can see that
there are different ideas out there - I posted this question with a
couple of other engineering/physics groups - same result.

I am thinking that the idea of the lack of integrity/reliability of the
individual strands in stranded wire, which could result in insufficient
current carrying ability and might not allow detonators to function
properly, seems like a good answer as far as the functioning of the
wires. I also see the logic in the other ideas about ease of handling.

However, as you can read on the web, various states i.e. PA, NJ etc.
not only require by law that detonators have solid leg wires - but
that all wiring in the blast circuit be solid conductor also.

This leads me to again see the logic of the idea the physical integrity
of the wiring - which in turn relates to the integrity current
capacity - is seen as critical enough to induce both, the manufacturers
to assemble detonators with solid wires, and individual states to pass
laws requiring that solid wiring be used for detonators and detonator
circuits.

PS I am glad for the replies and that a couple of people
actually found the question intriguing, I at first thought that no-one
would reply.

Instead of guessing , you should post a query to http://www.isee.org/
and get to the bottom of it. Your question has two parts, one relating
to b-cap construction and the other about the requirement for solid
conductors on all circuits. I really can't believe that second one, may
be a misinterpretation somewhere in reading the regulations. Try citing
the exact text.
 
G

gstringe

Jan 1, 1970
0
Of all your theories and list of choices, it really boils down to # 8
and slight variations therof. By the way I use a lot of Cat 5 stranded
cable, because of its flexibility and oddly, its connection
reliability. It is very easy to knick a solid small gage wire in the
stripping/termination process and therby assure yourself of a break
failure sometime in the future. Fixing broken wires that you yourself
caused rates a dope slap every time!!

Sometimes we can also overthink ourselves. ;-)
 
F

Fred Bloggs

Jan 1, 1970
0
However, as you can read on the web, various states i.e. PA, NJ etc.
not only require by law that detonators have solid leg wires - but
that all wiring in the blast circuit be solid conductor also.

This leads me to again see the logic of the idea the physical integrity
of the wiring - which in turn relates to the integrity current
capacity - is seen as critical enough to induce both, the manufacturers
to assemble detonators with solid wires, and individual states to pass
laws requiring that solid wiring be used for detonators and detonator
circuits.

Are you sure they're not talking about "solid" conductor versus
"wireless" detonation circuits?
 
R

Rich Grise

Jan 1, 1970
0
Of all your theories and list of choices, it really boils down to # 8
and slight variations therof. By the way I use a lot of Cat 5 stranded
cable, because of its flexibility and oddly, its connection
reliability. It is very easy to knick a solid small gage wire in the
stripping/termination process and therby assure yourself of a break
failure sometime in the future. Fixing broken wires that you yourself
caused rates a dope slap every time!!

Sometimes we can also overthink ourselves. ;-)

Yes, but learning to strip wire without damaging it is kind of satisfying.

Good Luck!
Rich
 
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