HAZARDOUS AREA TELEPHONE
TELE 6500 AR
Hazardous Area Telephone (HAT) is available for use in industrial sites which by their
very nature may be potentially hazardous. Installers must not work in hazard areas unless
the area has been made safe for the duration of the working time.
HAT must be securely isolated, in a safe area (by removing fuses or operating lockable
isolation switch if provided) from line and from any extension calling devices (n.b. these
may be Mains powered) before any work is carried out inside HAT, or on the associated
HAT, as supplied by BT, is a hard-wired, weather-resistant, water resistant (to I line
powered, dual signalling press button telephone certified for use in certain explosive
atmospheres'. It is for wall or table mounted use and offers the following facilities:-
LD or MF signalling (not switchable to MF during a call)
Earth or Timed Break recall *
Adjustable tone caller volume (high off low)
Last number redial (21 digits max)
Microphone mute (S button on keypad)
Reed-switch gravity switch (operated by magnet in handset)
Handset microphone inset used as tone caller
There is no PBX access pause with the Last Number Redial facility, when used on PBXs
requiring access pause, the access digit may be keyed manually and the remaining digits
sent by pressing the 'LR' button.
* Set by non user-accessible switches inside the telephone (which must be isolated before
opening, see SAFETY).
Made by DAC Ltd
Shobnall Street, Burton upon Trent, Staffordshire DE14 2HD
Telephone 0283 500500
Approved under approval number S/1363/3/J/453189 for PST or hard wired connection to the
network or to extensions of PBXs in categories 1 - 12 inclusive. N.B any PST connections
must be in a defined safe area.
BASEEFA (British Approvals Service for Electrical Equipment in Flammable Atmospheres)
Modifications which have not received BABT and BASEEFA approval must not be carried out as
to do so would invalidate approval making connection to the network unlawful.
REN, HAT has a REN of 1 provided the internal ring detect relay is not used and may be
(3-wire) connected with other HAT on the same circuit (within the limitations of REN). But
should be 2-wire connected (i.e. without the 'Bell' wire to LJU 3) if used with other
types of telephones (N.B HAT may then cause bell tinkle on other instruments whilst
Although HAT is approved for 3-wire connection to PST arrangements, this is not
recommended due to on-hook power requirements of HAT. The shunt effect of any parallel
connected instrument or extension bell is likely to prevent the HAT from operating.
HAT effectively has a REN of 2 If approved extension bells or lamps (available separately)
are to be connected via HAT internal ring detect relay, i.e. no more than 2 HAT's should
be connected for correct operation of the relay.
HAT is also designed to work from -20' C to +45' C, has protection against ingress of
moisture to IP 65 and is line powered requiring no additional power supply.
BASEEFA Certification. HAT is primarily intended for use in Zones 1 & 2 of hazardous
areas as defined in BS 5345 (i.e. where there are 'explosion risks due to the presence of
flammable gases or vapours').
Hazard Zones in BS 5345 are defined as follows :-
Zone 0 In which an explosive gas-air mixture is continuously present or present for long
Zone 1 In which an explosive gas-air mixture is likely to occur in normal operation.
Zone 2 : In which an explosive gas-air mixture is not likely to occur in normal operation,
and if it occurs will only exist for a short time.
The cabling to the telephone, where it passes through Zones 1 or 2 must comply with BS
5345 parts 6 & 1.
HAT (or associated cabling) is not certified for and must not be installed in Zone 0 or in
areas where there are combustible dusts.
NB It is the customer's responsibility to define the types of hazards and Zones where they
may be present, details of these must be obtained from, and cable routing and equipment
siting must be agreed with customer's site safety representative or other authorised
person before any work is started.
HAT must be installed in accordance with the installation instructions supplied with the
instrument. The signalling, recall and tone ringer loudness switches are inside the
telephone and must be set on installation.
n.b. The LD/MF signalling switch must never be left in the mid position.
The telephone must be isolated from line before the telephone case is opened in the hazard
areas (see 'Safety').
Cable terminations are as shown below, the cable entry holes in the case are threaded to
accept standard 20mm conduit fittings or glands. Where conduit is used, the ends must be
sealed with 'Mixture No. 2' to prevent any entry of gas from the conduit.
After installation and before commissioning HAT should be inspected as per section 3 of BS
5345 : Part 6 and cabling should be inspected as per initial inspection in Table 4 of BS
5345 : Part 1.
It is important that connection of the HAT base moulding to conduit, MI or armoured cable
gland is carried out by competent persons eg approved electrical contractors.
Where the HAT base moulding is fitted separately to the rest of the telephone the
following precautions must be taken to retain warranty and BASEEFA certification :-
i. The base moulding must be suitably protected whilst it is open and the sealing lip must
be free of any damage.
ii. The telephone 'top half' and line termination circuit board must be suitably protected
whilst separated from the 'base moulding'.
iii. The insulating washers must be placed on the middle pair of support pillars to
prevent termination board tracks short circuiting on the pillars.
A Leg (5)
B Leg (2)
Connection arrangements for HAT (and extension HATS)
n.b. * A wire link must be fitted between terminals S2 & C3 on first or single HAT
only, to connect the ringer circuit capacitor.
HAT has a conductive case which must be earthed by connection to metal conduit, metal
sheath of mineral insulated cable or by use of approved metal gland to sheath of armoured
cable. The threads of conduit bushes/ cable glands where they couple up to the threaded
cable entry holes in the instrument case must be sealed to prevent ingress of explosive
vapours, they must also make good metallic contact with the case of the instrument to
maintain earth continuity, if this is not possible then the HAT earth bonding kit
(available extra) must be used.
Suitable approved extension calling devices (bells, lamps, hooters etc) should be
connected to HAT. The relay contact switching limits are 250VAC at 5 Amps or 30V DC at 5
Amps, the 'Live' supply must be connected to the 'Ring detector contact'.
Calling device wiring must be kept away from telephone cabling, HAT must be isolated from
Line and external power before HAT case is opened (See SAFETY).
Maintenance of HAT is restricted to functional testing, visual inspection of case and
cable entry seal integrity, checking the signalling, recall and tone ringer switch
settings are correct or instrument changeout. There are no field replaceable parts and if
the instrument appears faulty must be replaced. To avoid disturbing conduit, MI or
armoured cable glands on HAT's where there is no damage to the base moulding, the base
moulding may be left in place and just the 'top-half' and line termination board replaced,
the faulty instrument must be re-assembled with the back moulding of the replacement HAT
for return under warranty or repair.
n.b. The precautions listed under Installation must be taken.
The telephone must be isolated from line before the telephone case is opened in the hazard
areas (see 'Safety').
HAT and associated cabling is subject to the Periodic inspections, Testing and Maintenance
requirements of BS 5345: Part 1, HAT is also subject to the Inspection, Maintenance and
Testing section of BS 5345: Part 6. These recommend inspections at no greater than two
yearly intervals and tests at no greater than three yearly intervals.
N.B. Testing should be carried out in consultation with the customers site safety
representative (or other authorised person).
Care must be taken not to damage telephone case or cable entry seals or internal
components whilst working inside HAT. When table mounted, the lower case moulding is wedge
shaped and may be turned round to give. a convenient working angle, it is important to
turn this in a clockwise direction so that the internal linking cable stows neatly.
When wall mounting HAT , care must be taken not to strain the linking cable which joins
the two halves of the instrument case.
Description BT Item Code
HAT 87 7885
HAT Wall mounting bracket 87 7886
Mixture No2 07 1638
earth bonding kit Manufacturer's code 100-02-0039-001
(available direct from DAC Ltd)
Fixing Screws:- For direct mounting - Pan-head screws max dia 6.5mm (max head dia 12mm)
length 15mm plus depth of wall penetration (4 required). For use with wall bracket - Any
suitable screws/bolts up to 1OMM dia.
N.B. Screws or other fixings must be weather/ corrosion resistant and suitable for use in
the particular environment.
(when single wire armoured or braided cable used) - Any suitable type approved by BASEEFA
to 'EX e', they must be the correct size for the cable sheath diameter and fitted by
Normal hand tools including Screwdriver Instrument No.1 (for cable terminations),
Screwdriver Cabinet 5" (for direct wall mounting), Hexagonal Wrenches ('Allen' Keys)
of the following sizes:-
5mm (e.g. Wrench Ball ended 5mm Item Code 14 1761) to open the telephone.
10mm (local purchase) to remove additional conduit entry plug (if required).
2.5mm (local purchase) to remove internal earth bonding plate (it required).
Tools as necessary to connect conduit bushes/ cable glands to cable entry in telephone
case (for use by competent persons only).
Site approved insulation and earth-loop impedance testers.
N.B. All Tools and test equipment are subject to approval by customers site safety
representative or other responsible person.
Idle - Normal capacitor loop, additionally HAT draws on-hook current (typically 21 ma) to
maintain stored/last number memory. This may give apparent 'Low Loop' line test
Seized - Normal press button telephone loop. The electronic keypad and transmission
circuitry may give 'high resistance' tele-loop line test conditions as with other press
HAT may be used as direct replacements for existing Flameproof telephones. When used to
replace these instruments, cabling through zones 1 & 2 must be checked and if
necessary modified so that it conforms to BS 5345 Part 1. This may require re-cabling in
conduit through hazard areas. After any changes or alterations, the complete system should
be inspected as per Installation/Commissioning.
A local record must be kept of inspections and test results.
The Tone caller volume switch should normally be left in the loud position on installation
unless the customer requests otherwise (the 'quiet' position is very quiet). Customer
requests for louder or extension bells should be referred to sales for consideration of
approved additional bells/ lamp signalling systems.
MF tone applied for as long as keypad button pressed, with a minimum tone burst 100 milli
Earth recall is via a solid state switch which will only operate when correct line
conditions are present, hence HAT is not suitable for use as an Earth calling, power fail
terminal' on earth calling PBXS.