English – MEDC DB18 User Manual

Page 3

English

1. INTRODUCTION
This loudspeaker, intended for use in potentially explosive gas atmospheres, has a power rating of up to 15 watts

and is suitable for use in all gas groups including hydrogen.

2. INSTALLATION
General

When installing and operating explosion-protected equipment, requirements for selection, installation and

operation 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 DB18 is mounted via 2 off Ø7mm (Ø0.28") fixing holes in the ‘U’ shaped stirrup/mounting bracket. If

required, the unit can be initially placed via the Ø13mm (Ø0.51") central hole in the stirrup. The unit can be

rotated to the required position and fixed via the two other holes.
MEDC recommend the use of stainless steel screws.
Cable Termination
CAUTION: Before removing the cover assembly, ensure that the power to the unit is isolated.
Unscrew and remove the 2 off screws holding the cover assembly to the base. Keep in a safe, accessible

location.
Remove cover to gain access to the interior.
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 con-nection where local codes or authorities permit or require such a

connection.
Once termination is complete, carefully push the cover assembly back onto the base, avoiding damage to the

mating surfaces. Please Note: The cover should be fitted in the orientation as supplied by MEDC to avoid the

cover fouling on the internal components. Replace the 2 off screws into the holes in the cover assembly and

tighten evenly.

3. OPERATION

The operating voltage of the unit is stated on the unit label.
The speaker is available as a 15W version only.
Different sound levels can be obtained by selecting the transformer tappings in the unit (see table below)

TRANSFORMER

POWER

TAPPINGS

15W

1:2

2:3

7.5

3:4

1:3

2:4

1:4

0.8

11/07