Question:  I just purchased a small PL system consisting of one PK-7 PSU, three RS-601 beltpacks and two KB-701 speaker stations.  When I wire up all the components to my PK-7 power supply the units shuts down and shows an overload LED indication.  If I add up the current consumption of all the attached units it adds up to 370mA, the PK-7 indicates it is rated for 400mA continuous load.  Am I doing something wrong?
Answer:  The typical current consumption is listed on the data sheets for the RS-601 beltpack and KB-701 wall mount speaker stations.  As there are some variations on current drain for any particular unit it could quite possible that you are hitting the limit of the PK-7 power supply (the calculated current use is approximately 370mA, the PK-7 can only supply 400mA worst case), it is always a good design goal to factor in sufficient headroom with the power supply or main station when designing a Clear-Com party-line system.  A good design goal is to only use approximately 65 - 70% of the available current capability of a Clear-Com power supply or main station, this leaves in some headroom for future expansion. 
In the case of this design it would be recommended that the PK-7 be replaced with a PS-702 or MS-702 main station which is capable of supplying up to 1.2 amps.  This would provide up to 500mA of additional headroom for future expansion of the system (370mA + 500mA = 870mA total current load).