14. stated ampere hours, abbreviation Ah, and calculated
at the 10h rate which the steady load current which would completely
discharge the battery 10h. rapid charge discharge encourages the plates to
buckle, and may cause permanent damage.
On new premises the electrical contractor may install sockets and the asso-
ciated wiring the point intended line entry, but the connection the
incoming line the installed master socket must only made the tele-
phone company’s engineer.
Each telephone extension bell marked with ringing equivalence
number (REN) the underside.150, which will rise 1. the level falls, must topped with distilled water. The sepa-
rators are made porous insulating material, such wood ebonite,
and the whole assembly immersed dilute sulphuric acid solution in
a plastic container.
Maintenance lead-acid batteries
● The plates the battery must always covered the dilute sulph-
uric acid.
● maintain battery good condition should regularly
trickle charged. The spe-
cific gravity cell can tested with hydrometer.
On existing installations, additional secondary sockets may installed to
provide extended plug-in facility shown Fig.
● Battery connections must always tight and should covered
with thin coat petroleum jelly. Each exchange line has maximum
. Any number of
secondary sockets may connected parallel, but the number tele-
phones which may connected any one time restricted.280 when fully charged.Electrical installations and wiring systems
343
A lead-acid battery constructed lead plates which are deeply ribbed
to give maximum surface area for given weight plate.
Battery rating
The capacity cell store charge measure the total quantity of
electricity which can cause displaced around circuit after being
fully charged.
Telephone socket outlets
The installation telecommunications equipment could, for many years,
only undertaken British Telecom engineers, but today electrical
contractor may now supply and install telecommunications equipment. The plates are
assembled groups, with insulating separators between them.6. discharged cell will have specific
gravity 1.
● The specific gravity relative density the battery gives the best
indication its state charge.3). Therefore, battery will provide a
steady current for 10h.62.
● The room used charge battery must well ventilated because
the charged cell gives off hydrogen and oxygen, which are explosive
in the correct proportions (IEE Regulation 560
