MEDC DB20 - Manual (Page 3)

English
1. INTRODUCTION
This range of loudspeakers, intended for use in potentially explosive atmospheres, has a power rating of 8W.
The unit is available in a number of versions suitable for use in the following gas/dust groups.
ATEX Version
IIB GAS GROUP UNIT – Exde IIB T3 (Tamb -50°C TO +70°C).
IIC GAS GROUP & DUST UNIT – Exde IIC tD A21 T130°C (Tamb -50°C TO +70°C) IP66 to IP67.
IEC Version
IIB GAS GROUP UNIT – Exde IIB T3 (Tamb -50°C TO +70°C).
IIC GAS GROUP & DUST UNIT – Exde IIC tD A21 T130°C (Tamb -50°C TO +70°C) IP66 to IP67.
The body and cover are manufactured completely from a UV stable glass reinforced polyester. The outer flare is
manufactured from ABS. Stainless steel screws and mounting bracket are incorporated thus ensuring a corrosion
free product.
2. INSTALLATION
General
When installing and operating explosion-protected equipment, requirements for selection, installation and op-
eration should be referred to eg. IEE Wiring Regulations and the ‘National Electrical Code’ in North America.
Additional national and/or local requirements may apply.
Ensure that all nuts, bolts and fixings are secure.
Ensure that only the correct listed or certified stopping plugs are used to blank off unused gland entry points
and that the NEMA/IP rating of the unit is maintained.
The DB20 is mounted via 2 off Ø7mm fixing holes in the ‘U’ shaped stirrup/mounting bracket. If required,
the unit can be initially placed via the Ø13mm central hole in the stirrup. The unit can then be rotated to the
required position and fixed via the other holes
The fixing holes have been designed to accept an M6 screw or bolt. MEDC recommend the use of stainless
steel screws.
The elevation of the unit can be adjusted by loosening the 2 off M6 screws which fasten the stirrup to the horn.
The unit can then be adjusted by rotating to the required position and then tightening the M6 screws.
The DB20 should be positioned such that debris, dust or water cannot settle in the re-entrant horn.
Cable Termination
CAUTION: Before removing the cover assembly, ensure that the power to the unit is isolated and gas and/or
dust atmospheres are not present.
Unscrew the 3 off M5 captive screws holding the cover to the enclosure. Remove cover to gain access to the
interior of the terminal chamber.
Cable termination should be in accordance with specifications applying to the required application. MEDC
recommends that all cables and cores should be correctly identified. Please refer to the wiring diagram provided
with the product.
Ensure that only the correct listed or certified cable glands are used and that the assembly is shrouded and
correctly earthed.
All cable glands should be of an equivalent NEMA/IP rating to that of the speaker and integrated with the unit
such that this rating is maintained.
The internal earth terminal, where fitted, must be used for the equipment grounding connection and the external
terminal is for a supplementary bonding connection where local codes or authorities permit or require such a
connection.
Once termination is complete, replace the cover and tighten the 3 off M5 captive screws evenly. Ensure the cover
seal is correctly seated in its groove during re-assembly.
© MEDC 2006 11/07