¢ WHAT ARTICLES WOULD YOU LIKE TO SEE? LET US KNOW: [email protected]
CROSSWORD
ACROSS
1 Pale sea-green gems (11)
8 Young dog (3)
9 Unpleasant or annoying people (5)
10 Doughnut-shaped roll (5)
11 Organ of sight (3)
12 As soon as possible (abbr) (4)
14 There are four of these in a year (6)
17 Cuts into small pieces (5,2)
19 Impious; ungodly (6)
20 The US gorilla who learned sign
language (4)
24 Hip-hop (3)
25 The former Princess of Wales (5)
27 Main artery of the body (5)
28 Be ill (3)
29 Artificial gems (11)
DOWN
1 Cessation of breathing, esp. in sleep (5)
2 Wharves (5)
3 To stretch high in order to get something
from a shelf (7)
4 To chop finely or puree, e.g. potatoes (4)
5 Red gems (6)
6 Bother someone with repeated
complaints or fault-finding (3)
7 Beauty shop (5)
13 Vietnamese noodle soup (3)
14 Secret agent (3)
15 Extinct bird (3)
16 Fur pouch worn with a kilt (7)
18 The later part of life (3,3)
19 Beneath (5)
21 Once married to Tom Cruise, .....
Holmes (5)
22 Many-coloured gems (5)
23 Measure of current (4)
26 The former Cassius Clay, Muhammad ...
(3)synonym of 1 across (4)
20 Stringed instrument (5)
22 Scottish or Irish Gaelic (4)
25 Upper limb (3)
THE CABLE GUY TECH GUIDE
Cable Installation Information – PART 2
Common issues associated with PVC insulated
and sheathed cables “PVC Cables”
Green Goo
Also known as “Green Slime”, this phenomenon is
characterised by the appearance of a sticky green
exudate leaking out of PVC-insulated wiring at locations
such as switches, hot points and light fittings. It is a
common occurrence in both Australia and New Zealand.
The green goo problem is predominantly associated
with older (25+ years) TPS-type cables operating in a
warm environment. The exudate comprises a plasticiser
that has migrated out of the PVC insulation, coloured
due to reaction with the copper conductor, and that has
subsequently travelled - by capillary action and/or gravity
– along the conductor to emerge at a termination point.
Due to its stickiness and unsightly colour, the goo has
a high nuisance value, however it poses no significant
health hazard. It may be cleaned from surfaces by wiping
with a rag soaked in a petroleum- or alcohol-based
solvent (such as meths).
The long-term consequence of the exudate is that it
represents a de-plasticising of the insulation, meaning
that as the process continues, the PVC will eventually
become brittle, and crack.
TPS Cables in Polystyrene Thermal Insulation
With the increasing use of polystyrene block insulation
in houses and caravans, it is important to explain the
potential problem that arises when PVC sheathed and
insulated cables come into direct contact with this material.
The plasticiser that is added to PVC to make it flexible,
has a tendency to migrate out of the PVC and into
materials with which it is in contact, particularly where
those materials – such as polystyrene and polyurethane
- have a great affinity for the plasticiser. This will lead
to the PVC's becoming progressively harder and more
brittle, while in contrast the polystyrene will appear to
“melt” as it absorbs the plasticiser.
The rate of migration is dependent upon the relative
thickness of the materials, the temperature, and the
amount of surface area in direct contact. Accordingly,
the rate of deterioration of the PVC cable can vary
considerably under different circumstances.
To mitigate the problem it is recommended that the
amount of direct contact between the cable and the
polystyrene be reduced as much as possible. Effective
ways of achieving this include positioning the cable with
an air gap between the sheath and the polystyrene, or
installing the cable within a rigid PVC or PE conduit.
Stay tuned for more articles
related to cable technical
guide from Nexans Olex.
TRUSTED BY AUSTRALIANS FOR OVER 75 YEARS
AUG – SEPT 2019 GEMCELL.COM.AU
47