64.
Electric space heating circuits
Electrical heating systems can broadly divided into two categories:
unrestricted local heating and off-peak heating.
.15. All three systems use
the thermal storage principle, whereby large mass heat-retaining mate-
rial heated during the off-peak period and allowed emit the stored heat
throughout the day. 14.
DP switch for
functional switching
DP switch for local
isolation during maintenance
Heat resistant
flexible cord
Supplementary
bonding
Water vessel
15A switch fuse
or 15A fuse in
consumer’s unit
FIGURE 14. 14.17
Immersion heater wiring.19.
Ducted warm air systems have centrally sited thermal storage heater with
a high storage capacity.18 for wiring arrangements. 14. Heating appliances where the
heating element can touched must have switch which disconnects
all conductors. See Fig.Electrical installations and wiring systems
295
See the section supplementary equipotential bonding later this chap-
ter and Fig. The wiring arrangements for this type
of heating are shown Fig. This requirement includes radiators which have element
inside silica-glass sheath.
When calculating the size cable required supply single-storage
radiator, good practice assume current demand equal 3. The unit charged during the off-peak period, and
a fan drives the stored heat the form warm air through large air ducts
to outlet grilles the various rooms. 14. Each radiator must have a
20A means isolation adjacent the heater and the final connection
should via flex outlet. The final circuits all off-peak heating installations must
be fed from separate supply controlled electricity board time clock.
Off-peak heating systems may provide central heating from storage radia-
tors, ducted warm air underfloor heating elements.
Unrestricted local heating may provided portable electric radiators
which plug into the socket outlets the installation. This will allow the radiator changed future time with
the minimum disturbance the installation. Fixed heaters that
are wall mounted inset must connected through fused connection
and incorporate local switch, either the heater itself part the
fuse connecting unit, shown Fig.4kW at
each point
