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Pigtails

Pigtails

(OP)
Let's say you have a part that requires electrical input to work.  You need to get the electrical signal through a bulkhead on the exterior of the part, and you come up with two designs.

In the first design, the wires simply travel through a small hole in the bulkhead.  The hole is then backfilled with epoxy, leaving the wires hanging from the part.

In the second design, a connector is incorporated into the bulkhead on the part, and the wires run from the interior of the part to the connector.

When discussing these two designs, what engineering term/phrase would you use to distinguish the difference between the two?

I have been referring to the first design as "pigtailed" and the second design as "connectorized."  Is it correct to refer to the wires hanging from the first design as "pigtailed?"  If not, what engineering term would be appropriate?

Taking it a step further, assume the hanging wires in the first design are terminated in a connector that mates to the next-level assembly.  Does this make a difference in determining whether these wires can be referred to as pigtailed?

I'd appreciate it if a few people could weigh in on this topic, especially the EE's out there.  A colleague recently asserted that I am misusing the word "pigtailed."  I will change my terminology if either

a)  I am indeed misusing the word "pigtailed"
b)  there is a more appropriate engineering term/phrase to describe the first design

RE: Pigtails

Off the cuff...I would say "un-terminated conductors".  Comment: I hope these are not exposed conductors, if you need quick access to the conductors, but do not want a connector, why don’t you use a terminal board?

RE: Pigtails

Your use of "pigtail" is in-line with common colloquial use.

Term "flying lead" is sometimes used for connecting wires dangling from a part or assembly.  You could have "unterminated flying lead", and "connector-terminated flying lead".

RE: Pigtails

the connector-less design requires a bung (as a pressure seal), whereas the connector-type of design (probably more correctly called a disconnect) doesn't.

so why not "continuous cable bung-type feed thru" (or just bung feed thru) and "disconnect feed thru" ... these should be clear enough terms

RE: Pigtails

I would use "Bulkhead Assy, Feed Thru" and "Bulkhead Assy, Connector" .. or something similar.

Chris
Systems Analyst, I.S.
SolidWorks Pro 06/PDMWorks 06
AutoCAD 06
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

RE: Pigtails

If you told me I was getting something with a pigtail to connect to my power supply, I would know what you mean.

If you told me I was getting a continuous cable bung-type feed thru I wouldn't.

RE: Pigtails

I don't want to start a voting procedure, but I do understand ctopher's post the most clearly.
respectfully

RE: Pigtails

So based on all this, would you just bung the connector up there and call it done?

RE: Pigtails

I was thinking "loose leads" and "loose connectors"?

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Pigtails

It depends on the context, I would use the term "un-terminated" or "striped and tinned" wires/leads/conductors/lines, if they were actually striped and tinned.  I've never heard the term pigtailed unless refering to hair styles.

"Art without engineering is dreaming; Engineering without art is calculating."
Steven K. Roberts, Technomad
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Pigtails

The first time I heard the term "pigtail" in any context other than a hairdo, it was the mic/tel lead coming out the back of a flying helmet - complete with jack plug on the end.  That actually looked a bit like its namesake, and could be where the expression came from.

A.

RE: Pigtails

Emerson uses the term "pigtail" in their documentation.

I think that if you use the term pigtail, most people will understand.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Pigtails

Hello Ashereng
I think that steam pigtails were probably the first use of the term in industry and were picked up by the electrical people later.
I know a pig tail as a loose wire for future connection, usually to a device. For instance, in an outlet box an incoming neutral wire will be spliced to one or more outgoing neutrals and a short "pigtail" 3 or 4 inches in length will be included in the splice for connection to the local receptacle.
I would call a wire passing through a hole a "pass through".
A fitting to pass a service through a plate or a bulkhead is a "Bulkhead connector". Electrical or tubing. The little "F" connectors for connecting co-ax, the ones with the extra locknut and washer, are bulkhead connectors. That's what the washer and nut are for. Similar type fittings are available to connect various sizes and types of tubing through a plate or bulkhead. Still bulkhead fittings. This type of connector may have new names now, but for many years you would find them in the catalogs under "Bulkhead connectors" or "Bulkhead fittings".
respectfully

RE: Pigtails

I have always called connectors without pigtails Bulkhead fittings.
 It is interesting to note that Cannon calls their bulkhead fitting shells by the designator "TBF" The bf I can figure out is the "T" terminal? or "termination"?
B.E.

RE: Pigtails

The terms "bulkhead fitting", "pass thru", or "feed thru" can all be used with electical, fluid power, plumbing, fiber optic and other "media".  If used by itself it is ambiguous.

RE: Pigtails

I wouldn't understand pigtail as a dangling cable.

In my world, it has always meant what you get when you twist the shield of a shielded (mesh shield) cable to get a wire-like conductor to connect to a grounding terminal.

Not that you should do that (a low-impedance connection is done with a clamp) but the word pigtail was, as I see it, reserved for that type of arrangement.

Gunnar Englund
www.gke.org

RE: Pigtails


The only pigtail I ever knew and was always after (not any longer now) was the one that dangled at the back of school girls.

We called the cables just connector-cable, and the coaxial shield, the 'grounding of shield.'



RE: Pigtails

(OP)
Thanks for all the replies.

From what I can tell from the responses, the term "pigtail" is fairly colloquial, but commonly used.

I have seen it a lot in product literature, but mostly with fiber optics.  For example, many companies refer to the fiber connected to their fiber-coupled laser diodes as pigtailed.  This means the fiber is butted against the diode and usually glued in place.  In this case, the fact that the device is pigtailed is significant because if the fiber is damaged, it can be a fairly big problem, since fiber optics can not be spliced without incurring significant losses.  Some devices have a connector interface between the fiber and laser diode, allowing for easier fiber replacement in the event of damage.  Such devices are generally much more expensive.

I have also heard people use the term when referring to electrical leads.  In my case, I'm using the term "pigtailed" to try to make it clear that if the cable is damaged, the entire part must be replaced (my application does not allow for splicing due to quality requirements and space limitations).  In the case of the connectorized version, only the connectorized cable (which is a completely separate part with a separate part number) would need to be replaced in the event of cable damage.

Also, the bulkhead example I gave was just an example that made it easier for me to describe my question.  In most cases, the parts I work on don't really have a bulkhead, but a decision still needs to be made on whether to incorporate a connector into the part, or to have "flying leads," which I've been referring to as pigtailed.   

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