This section contains the standard VDC in-house wiring specifications used with the more common audio multipin connectors found in this catalogue. All systems manufactured at VDC follow these wiring schedules, making maintenance and system expansion a simple procedure. The use of a standard specification also makes the practice of sub-hiring, common in the P.A. industry, an easy and trouble-free exercise. If you require any other VDC wiring specifications please call.
A patch bay is normalled when the top jack socket (output) and bottom jack socket (input) of a vertical pair are connected together, allowing the signal to pass through the patch bay, when no patch cords are inserted. There are three methods of normalling a patch bay: half normalling, single normalling and double normalling.
When no patch cord is inserted, the signal passes from the top jack (output) to the bottom jack (input) of a vertical pair. When a patch cord is plugged in the top jack, the signal still passes to the bottom jack, allowing a parallel for example. When a patch cord is inserted into the bottom jack, its connection from the top row is broken.
When no patch cord is inserted, the signal passes from the top jack (output) to the bottom jack (input) of a vertical pair. When a patch cord is inserted into either the top jack or the bottom jack, the connection is broken.
When no patch cord is inserted, the signal passes from the top jack (output) to the bottom jack (input) of a vertical pair. The connection can only be broken when a patch cord is inserted into the top and the bottom jacks.
NOTE: Lines 1-36 are the standard IEC colour code. Lines 37-64 are the Van Damme extension.
A single vertically suspended cable is subjected to direct flame from a Bunsen burner for a pre-specified time dependant on the overall diameter of the cable. To pass this test the cable must stop burning when the flame is removed and evidence of charring or burning of the cable must not extend 50mm beyond the directly flame exposed section of the cable.
Overall diameter ≤ 25mm time under flame 60 seconds Overall diameter >25mm and ≤ 50mm time under flame 120 seconds
IEC 60332.1 proves the fire retardancy of a single cable under flame; where cables are bunched together as in a typical installation IEC 60332.3 is the test used. Cables which are individually proven as fire retardant may, when bunched together, still propagate flame.
Test cables (minimum installed length 2.5 metres) are vertically suspended on a ladder within a fire test cabinet 1 metre wide by 4 metres high by 2 metres deep A propane burner is used to subject the bottom of the bunched cable run to flame. Air within the cabinet must be refreshed at a rate of 5000 litres ± 500 per minute and the temperature maintained at 750oC.
Category C definitions for this test are for cables with 1.5 cubic litre of insulating material per 1 metre of cable; time under flame is 20 minutes. To pass this test the cables must self-extinguish when the burner is removed and the flame must not have propagated over 2.5 metres.
A sample of the cable (500 – 1000mg) is burned in a ventilated combustion furnace at 800oC for 20 minutes and the resulting fumes are forced into gas washing containers. Using chemical titration it is then possible to determine the amount of halogen gas relative to the original mass of the sample. This test requires the relative amount of halogen gases to be ≤ 0.5%; however with halogen free materials a result of ≤ 0.3% is usually expected.
A 1000mg sample of the cable is burned in a ventilated combustion furnace at 935oC for 30 minutes and the resulting fumes are forced into gas washing containers. Using the relevant laboratory test equipment the acidity of any gases present and their conductivity is measured. To pass this test pH value must be ≥ 4.3 and conductivity must be ≤ 100μS/cm.
A sample of the cable is suspended over a tray containing 1 litre of alcohol in a test chamber that contains a light source on one side and a photovoltaic cell on the other. The alcohol is ignited, air is allowed to circulate and smoke will be emitted. The test finishes either after 40 minutes or when the density of the smoke within the cabinet has not increased over a 5 minute period. Using the light source and photovoltaic cell light intensity is measured and to pass this test the light transmittance factor must be ≥ 60%.