Compiled by ESV’s Electricity Technical
Advisor, John Stolk
energysafe continues its regular series
featuring some of the questions that
ESV receives on a range of electricity
installation issues, some of them relating
to gas installations. Also provided are
the answers together with references
to the Acts, Standards, Regulations
and Clauses that apply to them.
Question Answer Standard Clause
Does anyone know exactly what
rule applies to precisely how
much sheath should be removed,
behind accessories? Cables of a sheathed type need not be installed in a wiring
3000:2007 Clause 3.10.1
Where the sheath of a cable is removed, the exposed insulated
core of the cable requires to be enclosed.
100mm or less sheathing can be removed behind an accessory,
when the rear of the accessory is enclosed in a wall cavity.
What rule applies to precisely how
much insulation can be removed
when terminating conductors inside
the tunnel of a light switch? The insulation on a conductor shall not be removed any further
than is necessary to make the connection. AS/NZS
3000:2007 Clause 188.8.131.52
I have come across a new switchboard
that I needed to remove circuits from.
I found that none of the stranded
cables had been twisted and folded
when originally terminated.
I was under the impression that it is
required to twist and fold to terminate.
Or is it just best practice? The ends of stranded conductors shall be secured by suitable
means, so as to prevent the spreading or escape of individual
strands. They shall not be soft-soldered before clamping under
a screw or between metal surfaces. AS/NZS
3000:2007 Clause 184.108.40.206
I have been asked to install a
horizontal outlet sideways (vertically). The Wiring Rules do not prohibit a horizontal socket outlet being
installed vertically, but the installation must comply with the
requirements of Clause 4.4 of AS/NZS 3000:2007/ AS/NZS
3000:2007 Clause 4.4
The Wiring Rules requires the automatic disconnection of supply
in the event of an overload or short-circuit. AS/NZS
3000:2007 Clause 2.1.2(b)
3000:2007 Clause 6.3.3
Can anyone clarify if there is an
AS/NZS 3000 clause that suggests
this is not compliant?
If I use a 25A magnetic only circuit
breaker, does that mean my cable
needs to be rated at 250A?
The circuit in question supplies an
old overhead crane that only has direct
on line (DOL) single speed motors,
due to the unnecessary excessive
jogging by the operators the motors
are constantly only drawing starting
If I use a cable rated at 25 amps,
is the cables insulation likely to melt?
Anyone know what’s the logic behind
earthing pools and wet areas Reo?
Why would you want the Reo at
Twisting stranded cable and folding all conductors is best practice.
Magnetic circuit breakers offer predominantly short circuit protection
only, not overload protection. The circuit breaker can only be used
where overload protection is provided by another device.
The cable size is determined by the temperature rise.
The full load current of the motor must be known so that the
overload relay can be set. The peak current during starting should
also be known so that any adjustable instantaneous trip units in
the circuit breaker can be set close to, but not below this current.
Supplementary bonding is required to prevent voltage gradients
being introduced within the pool and water circulation system.
All extraneous conductive parts in zone 0, 1 and 2 including the
reinforcement steel within the pool, decks and conductive parts in
contact water filtration system are required to be connected together
to prevent difference of potential between conductive parts.
The equipotential bonding ensures that the conductive parts within
the pool zones and in contact with the pool water remain at the
same potential as a very low voltage is sufficient to present a
hazard to a person immersed in water.