The German installation of wire and wiring appliances reflect the need for conserving labor and material to an extent that in many applications his standards are well below USN requirements.  In many cases it would appear that standards are lowered in order to adopt mass production methods.  
June, 1946
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A. Introduction
B. Descriptive
  Air Circuit Breakers
  Distribution Boxes
  Fuses and Fuse Retainers
  Insulating Material
  Stuffing and Terminal Tubes
  Individual Switches
  Voltage Regulators
  Watertight Receptacles and Plugs
  Wire and Cable
  Wiring and Wiring Appliances for Switchboards and Power leads
  Ship's Electric Heater Units
  Ship's Galley Equipment
C. Conclusions
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  A.  Introduction  
          The scope of this report is to present in a general manner the German practices observed in type IXC vessels.  
          Individual components have been shipped to the Bureau of Ships, Code 660, Washington D.C. for detailed exploitation and reference should be made to their reports when they become available.  These components are listed below.  
          1.  Main Battery Air Circuit Breaker.  
          2.  Lighting Voltage Regulators.  
          3.  Watertight receptacles and Plugs.  
          4.  Rotary Type Snap Switches (to 600 A. capacity).  
          5.  Fuses and Fuse Retainers.  
          6.  Torpedo Charging Panel with associated equipment including motor-generator with controls.  
          7.  Torpedo Heating Panel with associated equipment.  
          In addition considerable information may be obtained from the German instruction book "Grundzuge für Electriche Unlagen - Berlin 1940 - Oberkommando der Kriegsmarine" (Outline for electrical Systems - Berlin 1940 - Navy High Command).  
          A separate section in this book is devoted to practices to be followed for submarine installations in which may be found discussions of the following subjects.  
          1.  Fundamental definitions.  
          2.  Tests for motors, generators and transformers.  
          3.  Practices with regard to sound silencing equipments including design concepts.  
          4.  Cable descriptions and ratings including one hour ratings.  
          5.  Fuse size application.  
          6.  Miscellaneous other information with regard to practically all electrical shipboard installations.  
  B.  Descriptive  
  I.  General  
          The German installation in this type vessel reflects the German need for economy of labor and material.  Standards are lowered to attain these ends.  
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          To amplify the above the following illustrations are presented.  
                  (a)  Cables of a given cross section are given two ratings - one for continuous duty and a one hour rating.  The latter being 50% more than the continuous duty rating.  
                  (b)  In order to take labor saving advantage of a community stuffing box and its inadequate methods of sealing for passing cables thru watertight bulkheads, the German lowered his compartment air test from 15 pounds to 3 pounds.  
  II.  Air Circuit Breakers  
          For detailed information with regard to Breakers and Controllers reference should be made to the German Instruction Book "E. Maschinen Haupt und Hilfsschalttafeln" (Electric Machinery - Main and Auxiliary Switchboards) which contains a detail description of the various breakers and contactors employed including pictures and detail drawings of the operating mechanism.  
          In addition, a circuit breaker has been shipped to the Bureau of Ships, Code 660 for detailed exploitation.  
          Observations at the Shipyard indicate that contactors and breakers are not as well designed as USN breakers and contactors both as to space and weight and to operating mechanism design.  Electrically operated breakers or contactors are not installed, the majority being manually operated although provision is made for tripping battery breakers from the Maneuvering Room.  A voltage coil is employed for this purpose.  
  III.  Conduit  
          Galvanized steel piping is used for conduit in the few applications made by the German.  These conduits are installed in circuits led from the Conning Tower to the Bridge.  Cone type fittings are used with the conduit.  
  IV.  Controllers  
          Controllers are discussed in detail in Report 2G-9C-S63.  
  V.  Distribution Boxes  
          The German distribution boxes are of no better design than present USN designs and in most cases would  
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  not meet USN requirements.  
          Designs vary to incorporate watertight, non watertight, and drip-proof features.  
          Housings and covers are either cast or fabricated from sheet metal.  When cast, tube terminals are cast integral with the housing.  
          Socket type rubber gaskets of rectangular cross section are used in watertight designs.  Captive screws are used thru out.  
          Quick opening fuse and distribution boxes are widely used.  In design these are somewhat similar to those used by USN in the V class submarines.  
  VI.  Fuses and Fuse Retainers  
          A description and drawings of German fuse design may be found on pages 9, 10, and 11 of German Instruction Book "Funklehrbuch der Marinenachrichtenschule, Teil I" (Radio Instruction Book - Naval Communication School Part 1.)  
          The fuse and fuse retainer shown on page 10 of the above reference is used in ninety percent of the applications.  These fuses are designed in various desired capacities from 6 to 600 amperes.  The practice employed is to use up to five different ratings in one size fuse body.  For example, two, fifteen, and twenty ampere capacity fuses are mounted in a fuse body of the same size, hence one size retainer is required for fuses of those capacities.  However, in order to minimize the possibility of misapplication, the fuse retainer is provided with a small phenolic washer at the bottom.  For each different fuse rating in that particular body size, the diameter of the hole in the washer differs to mate with the diameter of the pin cap at the bottom of the fuse.  
          The pin cap also serves as one contact of the fuse to which the fuse element is secured.  The top of the fuse is provided with a larger cap which is cemented to the fuze body.  Thus the fuse element is secured between the two caps.  In addition, provision is made for blown fuse indication.  In the larger sizes an additional small wire is secured to the lower cap and to a small colored cap which seats in the upper cap, when the fuse blows the colored  
     - 13 -


  cap falls from its seat.  The colors differ for each fuse size to provide means for ready identification of the fuse size.  
          The main weakness of the German fuses lies in the use of porcelain for the body, due to its inability to withstand high-impact shock.  
          The threaded ferrule on the fuse retainer cap is serrated to minimize the possibility of its becoming lose due to vibrational disturbances.  
          External shock mounting is not employed.  
          Fuses and fuse retainers of this type offer interesting possibilities for further development, particularly with regard to their space requirements.  Several have been shipped to the Bureau of Ships, Code 660 with the battery breaker for detailed exploitation and reference should be made to their report when it becomes available.  
  VII.  Insulating Materials  
          Materials for insulation are of the usual types varying from friction tape to molded bakelite products.  Observations made at the Shipyard indicate that the German had not advanced as far in this field as had the USN.  The German limited his application to relatively small parts, due primarily to his apparent inability to develop high shock insulating material.  
          "Melemine" or its equivalent has not been observed.  
  VIII.  Rheostats  
          Rheostats exist in various sizes and shapes, most of which are similar in design to present USN designs with the exception that porcelain is used extensively as an insulating material with its inherently weak shock characteristics.  
          A voltage regulator has been shipped to the Bureau of Ships, Code 660 for detailed exploitation, and reference should be made to their report when it becomes available with regard to the characteristics of German resistor wire.  
  IX.  Stuffing and Terminal Tubes  
          (a)  Tube terminals.  
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                  German tube terminal designs are similar to USN design, the major difference being in the packing seat.  The German seat is normal to the cable as contrasted with USN practice of having the packing seat at 45° to the cable.  
                  The German packing consists of a single circular rubber washer of rectangular cross section.  (Rubber insulation is used extensively in German cables).  
                  Tube body, washers and gland nuts are plated steel.  Provision is made in the gland nut on three surfaces of the hexagon shaped nut for small screws, one of which is used for grounding the armour of the cable.  
                  Where portable cables are used, a phenolic gland nut is substituted for the steel gland nut.  Otherwise the practice is the same.  
          (b)  Stuffing Tubes  
                  The German method of taking cable banks through watertight bulkheads is to use a community stuffing box.  Banks containing up to sixty cables, including main power, are passed thru the bulkhead in this manner.  
                  Its weakness lies in the fact that due to the interstices of the armor on the cable it is not possible to obtain a uniformly solid mass in way of the stuffing box, thus increasing the difficulties in obtaining a satisfactory compartment air test.  
                  In those cases where individual cables leave the pressure hull, stuffing tubes somewhat similar in design to USN stuffing tubes are employed.  The major difference is in the length of the tube which is greater due to the German's inability to attain a satisfactory pressure proof cable entrance.  
                  German practice in this case is to use armoured cable which is run thru conduit on the outboard side.  
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                  The sealing is installed on the inboard side of the stuffing tube.  It consists of pouring about 1-1/2" depth of sealing compound which is backed up by a standard circular rubber washer, a gland washer and finally the gland nut.  
                  On the outboard side the conduit is welded to the stuffing tube.  
                  On each stuffing tube of this type, a separate drain line and petcock is installed in such manner that it it outboard of the packing but it is located within the vessel.  This provides a means for checking the integrity of the conduit fittings.  
                  In the several cases where coaxial cables are run thru watertight bulkheads or the pressure hull, shear valves are employed.  These are rather elaborate affairs requiring two wrenches to be stowed near them for actuating the valve.  They can be operated from one side only, hence their value in watertight bulkheads is dubious.  
                  Two designs are used, one for single cables, the cutting edge of which operates as a petcock, the other a three cable unit, the cutting edge of which operates as a rotary knife.  
  X.  Individual Switches  
          By far and large, the German preferred rotary type switches.  These are found in capacities up to 600 amperes.  
          Simple spring and star wheel (spring loaded) operating mechanisms are used extensively.  
          In the smaller sizes, the German parts, except for the operating mechanism, are interchangeable with corresponding parts on USN switches.  The major difference being in the ratings given the switches, the German being 250 V 10 Amps D.C.  USN rating being 250 V, 5 Amps D.C.  The above USN switch is plan No. 9-S-4718.  
          Life tests made on the above German switch resulted in mechanism failure of the spring after an average of 12,475 cycles as compared with USN requirements of 37,500 cycles.  
     - 16 -


          In addition, rotary type switches of the following ampere capacities have been shipped to the Bureau of Ships, Code 660 for details exploitation and reference should be made to their reports when they become available.  
  XI.  Voltage Regulators  
          Two regulators are installed to obtain regulated 110 V D.C. from a variable power supply of 110 to 170 V. D.C.  
          Provision is made for manual and automatic operation.  A voltage sensitive relay controls two relays, which in turn control the direction of current flow in the armature of the drive motor.  The unit is similar to USN regulators currently being installed in submarines, being of approximately the same KW output.  
          For information with regard to its installation, reference should be made to report 2G-9C-S61.  
          In addition a voltage regulator has been shipped to the Bureau of Ships, Code 660 for detailed exploitation and reference should be made to their report when it becomes available.  
  XII.  Watertight Receptacles and Plugs  
          The German design W.T receptacle and plug consists of a molded phenolic housing in which the necessary metal inserts are provided for securing the covers.  Tube terminals are moulded integral with the housing.  
          Phenolic gland nuts and circular rubber washers of rectangular cross section are employed in the tube terminal.  A separate ground strap is mounted on the bottom of the housing to which the cable armor is grounded.  
          Suitable rubber gaskets are employed in way of the cover to obtain watertight integrity.  
          The standard German rotary snap switch is employed in the housing.  
     - 17 -


          The receptacle consists of an assembly of porcelain and brass parts.  Polarization is obtained by rotating the grooved contacts as desired, then locking them in position.  The use of porcelain is considered poor due to its shock characteristics.  
          Watertight receptacles and plugs have been shipped to the Bureau of Ships, Code 660 for detailed exploitation and reference should be made to their report when it becomes available.  
  XIII.  Wire and Cable  
           German cables exist in various sizes and number of conductors, both armour, shielded, and portable.  In nearly all cases rubber or synthetic rubber is used for insulation of the individual conductor and for the outer sheath.  
          All the rubber type insulation burns readily, thus minimizing any interest in German cables.  
          It would appear that standard methods of manufacture are employed.  However, it is presumed that detail information may be found in Nav Tech Report No. 78-45 of April 1945.  This report is not available in the Shipyard.  
          Detail information with regard to cable type and application is contained in the German instruction book references in the introduction.  
          The German practice of assigning one hour ratings to cables os an indication of his desire to conserve critical materials, and is worthy of consideration for war use particularly, in view of the fact that copper shortages forced electrical manufacturers to resort to copper plated steel for current carrying parts in many applications with its attendant increase in labour required for manufacture.  
          A description of a German watertight cable is contained in Report 2G-9C-S68.  It is used in conjunction with underwater sound installations and is the only cable of its type observed.  
  XIV.  Wiring & Wiring Appliances for Switchboards and Power Leads  
          The German application of wiring and wiring appliances is of simple design and in many cases considerably inferior to USN specification for comparable installations.  German practices include the following:  
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                  (a)  Soldered Terminals on larger cables.  
                  (b)  No attempt made to seal the cable insulation at the terminal entrance.  
                  (c)  Slotted stud with cap type screws securing the connection to the bottom of the slot.  These studs are usually assembled on porcelain bases in form of terminal boards.  
                  (d)  No wiring troughs are employed to protect and facilitate switchboard wiring.  
                  (e)  Leads connecting stationary components to instruments on hinged panels are run directly with a loop formed at the hinged side as contrasted with USN practice of using double sets of terminal blocks.  
                  (f)  Wire used in switchboard installation is provided with rubber insulation which does not have heat and flame characteristics.  
                  (g)  A minimum of hardware such as jam nuts, lock washers, flat washers is used thus increasing the possibility of losing the continuity of the circuit due to vibrational disturbances.  
  XV.  Hangers  
          The German design with regard to cable hangars is somewhat similar to USN designs.  The major differences lie in the fact that his hanger straps are generally thirty percent lighter in gauge and are usually spaced 10 to 25% further apart than required by USN specifications.  
          In most cases, except for main power cable banks his installations are similar to those shown as A2 on sheet 3 of 9-S-3980, Alt. 25 with the following exceptions.  The step hanger is tapped for 1/4" screws, round head screws are used in these holes to secure the strap hanger to the hanger support.  Jam nuts, lock or safety washers are not used to minimize the possibility of the strap becoming loose due to vibrational disturbances.  
          In main power cable banks which were run with auxiliary power and I.C. cable banks, the hangers are similar to that shown on Sheet 12 drawing 9-S-3980, Alt. 25 with the following exceptions.  
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                  (a)  Piece X stiffener is not used.  
                  (b)  The dimension from the step hanger to the hull is usually 2-1/2" rather than the 3/4" used in USN practice.  
                  (c)  1/4" round head screws in tapped holes secure the strap hangar to the step hanger.  
          In all cases strap hangers are formed to suit the cable lay.  Workmanship observed indicated that the forming was done at the cable lay rather then in the shop as is USN practice.  
          Arc welding is employed to secure cable hangers to the hull.  Zinc chromate was applied to the step hanger and weld to minimize corrosion.  Strap hangers are all galvanized for corrosion protection.  
          The effectiveness of the above corrosion protection is dubious.  Observation of cable supports in way of compartments in which plastic sheathing is employed for drip proof protection indicates that considerable corrosion was occurring due either to lack of application or the quality of the materials used.  
          Resistance or arc welded studs are not employed.  
  XVI.  Ship's Electric Heater Units  
          These units of 750 and 1000 watt capacities are portable radiant type heaters made from suitably formed sheet metal to which aluminum paint had been applied.  They corroded readily and are considered very inefficient for the purpose intended.  The power supply is obtained from the battery at 110 to 170 volts D.C.  
          For detailed information reference should be made to the German Instruction Book "Beschreibung und Betriebvorschrift für die Kuhlanlage Eletrische Kocheinrichtung auf U-805.  (Description and Operating Instructions for the Refrigerant and Cooking Equipment on U-805).  
          These heaters were not returned to the vessels after overhaul but were replaced with suitable USN heaters.  
     - 20 -


  XVII.  Ship's Galley Equipment  
          There is nothing unique or desirable about the galley equipment.  It has been removed during overhaul of the vessel and replaced with USN equipment.  
          For detailed information reference should be made to the German Instruction Book.  "Beschreibung und Bertriebvorschrift für die Kuhlanlage Electrische Kocheinrichtung" (Description and Operating Instructions for the Refrigerant and Cooking Equipment on U-805).  
  C.  Conclusions  
          The German installations described herein reflect the German need to conserve material and labor and in general may be considered inferior to comparable USN installations.  The exceptions to this may be determined from the reports on individual components as they become available from the Bureau of Ships, Code 660.  
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