[Ares-races] Re: 12 volt power connectors

[Jerry Reimer]

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>Molex 1545 vs Radio Shack 274-222 vs Radio Shack 274-151 vs Anderson Powerpole connectors
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One of the early issues identified with Molex, and the RS variations, is 
that of current capacity.  The standard Molex and 274-222 are limited to 
about 12 Amps.  While the RS 274-151 "heavy duty" is rated at 20 Amps. 
 When the contact pin and socket are used in housings containing 
multiple circuits, the current rating per pin drops.

A similar issue exists with the Powerpole connector design, especially 
in the very popular PP15 and PP30 connectors.  These two connectors 
share a common housing size and contact pin design.  However, they carry 
15 and 30 Amp current ratings, respectively.  How can this be, since 
they are physically identical?  The answer is in the size of the wire 
socket in the contact pin itself.  The PP15 contact pin accepts wire 
sizes 16-20 AWG, while the PP30 contact pin accepts wire sizes 12-16 
AWG.  The maximum current for a 12 gauge wire is less than 30 Amps. 
 Using a PP30 as the primary connector from a 30-50 Amp power supply may 
be inadequate as much as from the wire size as from the connector 
itself.  To overcome this limitation, some ARES groups have standardized 
on the 75 Amp rated Powerpole connector, who's physical size is 
incompatible with the 15/30 design.

A mnemonic for proper wiring is:  Red on the right, when viewed from the 
rear, with the hood down.

http://www.andersonpower.com/products/pp/sp.html

In migrating from the Molex/RS connectors to Powerpoles, snip the wires 
one to two inches away from the Molex/RS connector, then install 
Powerpole connectors on the free ends of the wires still attached to the 
Moles/RS connector.  This should result in a convenient supply of male 
and female Molex to Powerpole adapters, should you encounter either 
power sources or equipment without the proper connectors.

My ARES group recommends the PP15 and PP30 designs.

Jerry Reimer, KK5CA
EC NW Harris County ARES
DEC ARES District 14 - Harris County
ARRL South Texas Section