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Author Topic:   The Design of Everyday Things Electrical
jimh posted 09-09-2009 08:58 AM ET (US)   Profile for jimh   Send Email to jimh  
In another discussion, the design of electrical connectors with regard to the gender of the connector and how it should be used became a topic of discussion. A common practice with electrical connections is that the mating connectors are arranged in two genders, one with pins (which is usually called the male gender), and one with sockets (which is usually called the female gender). It is universal in the practice of electrical wiring that when a connector is provided in a circuit where there is a source of power, the connector attached to the side of the circuit supplying the power is a female gender, that is, it has sockets. To confirm this notion as being a common practice, one only has to look around their home at the electrical outlets for 115-VAC. The outlets are all of the female gender. The cords on appliances that plug into the outlets are all of the male gender.

It takes only the briefest moment of thought to appreciate why the connectors are arranged in this manner. If the 115-VAC power source were provided on a connector with protruding pins, there would be quite a hazard created. Accidental contact with the 115-VAC on the pins of the power outlets would be painful and dangerous, possibly fatal.

In a small boat the power distribution branch circuits carry only 12-VDC, but the same concept applies to use of male and female connectors. In circuits where there is a source of power, that portion of the circuit is provided on connectors which are female in gender. While 12-VDC may not be as much of a hazard to health as 120-VAC, contact with it can be dangerous.

A further concern is for the health of the electrical circuit itself. If you were to distribute 12-VDC on connectors with exposed pins, a short circuit could easily occur. An additional concern is that the 12-VDC voltage could come in contact with some metallic component of the boat which was not well bonded to the boat ground (or battery negative terminal). Any metal with an elevated voltage immersed in a liquid creates a galvanic corrosion situation which will begin to rapidly erode any less noble metals that are also immersed in the liquid.

For example, if a connector carrying the 12-VDC from the battery on an exposed pin were to accidently come in contact with some portion of the boat or motor, perhaps something as common as a transom mounting bolt, this component would immediate form a cathode in a galvanic corrosion circuit. The branch circuit carrying the 12-VDC may be fused with a current limiting device whose rating is too high to be tripped from this galvanic current. The result is very rapid corrosion of any less noble metals around the boat, for example the engine gear case or propeller.

For these reasons, there are simple everyday design considerations for electrical circuits regarding what gender will be used on circuits distributing power.

fishgutz posted 09-09-2009 10:17 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Understandable explanation. Very well put.
I have an exception. Perhaps my own.

I have two batteries in my console. I have a "pigtail" attached to each battery for charging. I do not have an onboard charger. The pigtails are red and black wires with a small connector/plug. The plug is the type that is sometimes used for a trolling motor plug. The red (+) wire has a female connector and the black (-) has the male connector, just as you described above. My portable charger has the mates for these connections. Red (+) has the female connector and the black (-) has the male connector. So the charger has just the opposite.

Kind of an odd situation. When there is no charger hooked up, the batteries are "hot". If the charger is used the charger is "hot".

I gave this a lot of thought before using this setup. I wanted something simple and cheap. Seeing as the charger has polarity and short circuit protection, this setup was most practical.

Bella con23 posted 09-09-2009 11:16 AM ET (US)     Profile for Bella con23  Send Email to Bella con23     
Fishgutz makes a very good point. However, in that situation I have seen recessed male connectors that leave no exposed pins. These recessed male connectors are usually on the battery side.
jimh posted 09-09-2009 09:49 PM ET (US)     Profile for jimh  Send Email to jimh     
It is quite unusual to have a connector arrangement which connects two sources of electrical current together, as FISHGUTZ described above with his charger and battery example. I don't know that there is a standard convention for that sort of arrangement.

I would suggest that the charger connector use the male gender because the current from the charger can be shut off or controlled, while the current from the battery cannot.

Bella con23 posted 09-09-2009 11:37 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
I would agree with Jim's assessment of the connector polarity. Fact is if I were wiring this connection I would wire as he suggests.

I was referring to the way my kids rechargeable toys are wired, but this may be due to the possibility that the charger is left plugged in, therefore leaving the energized end hanging.

Moe posted 09-10-2009 07:23 AM ET (US)     Profile for Moe  Send Email to Moe     
For 12 volt nominal DC connectors, many, if not most amateur radio operators use Anderson Powerpole connectors.

The standard ARES configuration is shown here:

jimh posted 09-10-2009 08:47 AM ET (US)     Profile for jimh  Send Email to jimh     
Anderson Powerpole connectors are used extensively for DC applications. However, they are not particularly suited for marine use because they are not intended for a wet environment and lack any sort of weather protection. I use them on my test bench to distribute 12-VDC. In my work I have seen them used inside large uninterruptible power supplies where they are intended to carry several hundred amperes of current. The same general contact design is used; its size is scaled in proportion to the current.

Regarding the design of the Anderson Powerpole connector, the connector body protects the electrical contact from exposure, and the electrical contact is a unique design which has no gender. That is, the same contact is used on both sides of the connector, and the contact mates with a copy of itself. The connector body is also similarly of a clever design. There is only one type of connector body and it also mates with itself.

The Anderson Powerpole connector is a good example of an electrical connector which as been designed for a specific purpose. Another great attribute of them is their low cost. And, of course, they can be field assembled.

There are so many different electrical connectors made these days that there always is "the right" connector for a particular job.

pglein posted 09-10-2009 01:38 PM ET (US)     Profile for pglein  Send Email to pglein     
I am sometimes confused about the male vs. female nomenclature when dealing with connectors that have rubber or plastic shielding around the male plugs, or which have a mix of individual male and female terminals within one connector. A very simple example of this is a "flat-4" trailer connector. While not all of these have the feature I'm talking about, many do. A "male" connector will sometimes have a shield that, when connected, envelopes the "female" connector within it. In a way, it becomes the female connector. This, of course, is somewhat further complicated by the fact that the typical "flat-4" trailer connector has three terminals of one gender, and one of the other. In this case, it's pretty obvious, the one with three male terminals is obviously the "male" connector. But what about a two wire connector of similar construction; like the ones used on removable Boston Whaler stern lights, or commonly seen as OEM terminals on removable VHF radios? Each have one male terminal and one female terminal. Which connector is the male? What do we call these type of connectors; trans-genders? Perhaps of more importance, which connector should be connected to the source of the current, and which should be connected to the draw? I would think that connecting the one with the positive side of the circuit in the female terminal to the source would be the most logical, but I am not sure that his is the convention.
number9 posted 09-10-2009 04:34 PM ET (US)     Profile for number9  Send Email to number9     
"flat-4" connectors are bi-gender but follow the general rules. The three battery/power side terminals are protected sockets. It would be interesting to see the patent on that connector.

There may be times when specialized connectors with both pins and sockets on the same side are used. Sometimes a separate circuit to a device powers it's output continuously but a control circuit also uses power to disable it when necessary and only one connector is used for both output/control. An example, a continuous duty solenoid valve that's normally powered that may need to be de-energized at times.

jimh posted 09-10-2009 06:03 PM ET (US)     Profile for jimh  Send Email to jimh     
There often is some confusion about the connector gender, as the contacts themselves often have an opposite gender from the connector body. In other words, connectors with the pins (male) are often part of a connector assembly that overall is a receptacle (female), not a plug. To resolve the ambiguity, the gender is normally associated with the contacts themselves.

A good example is the very popular XLR connector. The XLR male has pins for contacts, but they are enveloped in a recessed connector body which would be considered the female gender. The mating connector, the XLR female, has socket contacts, but it actually plugs into the connector body of the mating XLR male. Confused? Yes, it can be confusing.

pglein posted 09-14-2009 12:31 PM ET (US)     Profile for pglein  Send Email to pglein     
Yes, all this talk about mixed genders, and mating between genders has me feeling very "confused". ;)
bluewaterpirate posted 09-14-2009 12:42 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Ah the term gender bender .......
number9 posted 09-14-2009 04:05 PM ET (US)     Profile for number9  Send Email to number9     
Worked on airline electrical/avionics for years. A couple of years ago was when I first heard someone referring to gender when calling a connector socket a "female pin". Naturally after reading this topic I thought of that and now after some additional research understand it's a normal practice for some to use the gender term electrically.
Additionally thanks to Jim's good explanations and research, my understanding is much better of circuit design and why the socket connector is on the hot side. Something most don't even think about when replacing parts or doing a modification with supplied parts and working off a wiring diagram.
It's always a wonderful day when something is added to your knowledge base as we often get to do reading here.

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