As stated previously, during WW2, the Germans typically connected field telephone equipment with a single wire/ground connection if the field telephone lines were 3 kilometers or more from the enemy lines. The Nachrichtentruppen were also forbidden to cut telephone wire from a spool (Trommel). So, how was a field telephone connected to a wire if a significant portion was left of the spool?
Well, for example, suppose a field telephone line (Feldkabel) was run out to a field artillery command position from a regimental headquarters Abspannbock. The position is only one quarter of a kilometer away, so there is a quarter of a kilometer of wire left on the spool. The Nachrichtentruppen laying the field telephone line drop off the spool of wire at the position. The position’s field telephone is connected by stripping some of the insulation from the wire, then wrapping one bare end of a short piece of La wire around the stripped portion. A short piece of Lb/E wire is connected to the grounding stake. The end of the wire on the spool is isolated with some electrical tape. The spool, field telephone, and grounding stake are left at the command position. The artillery commander can now communicate with regimental headquarters.
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WW2 German Field Telephone Equipment 