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Electrical
news
Case study: Dangers of
non-compliant switchboards
Article submitted by David Webb,
DRC Switchboards, NESMA Technical
Representative on Standards
A licensed electrical inspector (LEI)
was requested to attend an electrical
installation consisting of a Pillar and a
Form 3b Main Switchboard. Both boards
were assigned a rating of 1600 amps.
The inspector was unsure of the suitability
of both boards considering AS/NZS 3000 wiring
Rules Clause 2.9:
2.9.3.2 Suitability
Switchboards shall be suitable to withstand
the mechanical, electrical and thermal
stresses that are likely to occur in service.
Switchboards complying with the relevant
requirements of the AS/NZS 3439
series of Standards are considered to meet
the requirements of Clause 2.9.3.
Note:
1 See also Clause 7.2.8.1 regarding
segregation requirements for safety
services.
2 See also Clause 2.5.5 regarding
requirements for protection against the
effects of arcing fault currents.
As a precaution, the Kiosk protection
was subsequently set below 800 amps.
The inspector referred the matter to ESV for
further assistance with evaluation of the design.
ESV engaged NESMA (the National
Electrical Switchboard Manufacturing
Association) to provide an independent
representative familiar with the details of
the standard and forms of separation to
assist with this evaluation.
On inspection
The switchboards appeared to be noncompliant with AS/NZS 3439.1-2002 and
AS/NZS 3000-2007, and therefore noncompliant electrical equipment as per
Section 54 of the Electrical Safety Act.
Specifically Sections 8.2.1, 8.2.3 and 8.2.7
of AS/NZS 3439.1: Heat rise, Mechanical
Strength, IP Rating and Separation.
In the absence of supporting verification,
the following was agreed by the switchboard
manufacturer who also attended the
site inspection.
IP rating
Reference Clause: AS/NZS 3439.1-2002
8.1.1 (g)—
The Pillar was nominated as IP 56. There
was no evidence of testing or verification to
AS/NZS 60529. Louvres were punched into
the side and inconsistent with the nominated
IP65 rating.
The main switchboard was nominated
as IP 44. There was no evidence of testing or
verification to AS/NZS 60529 on the sealing
provided on the switchboard.
Separation
Reference Clause AS/NZS3439.1-2002
8.1.1 (g)—
There was no separation to Form 3b or
derivation, or by calculation as required by
AS/NZS 3000 Clause 2.5.5.
Note: An attempt was made to make a
Form 3b switchboard by wrapping busbars
using PVC tape. Tape is specifically noted
as non-acceptable in AS/NZS 3439.1-2002
Clause 7.4.2.1.
Mechanical strength and short
circuit capacity
Reference Clause AS/NZS 3439.1-2002
8.1.1 (c)—
There was no evidence of any bus bar
supports. The bus bars that were attached
to the breakers were not consistent with the
manufacturer’s recommendations and no
verification test was provided.
Temperature rise
Reference Clause AS/NZS 3439.1-2002
8.1.1 (a)—
There was no ventilation on the main
switchboard. The Main Bus was of insufficient
size, for 1600amps. No evidence to support the
rating of 1600amps was provided, by either test
result or verification as allowed in
AS/NZS 3439.1-2002 Clause 8.2.1.1.
Note: Compliance can be verified using
AS 3439.1 Clause 8.2.1.1, by either:
»» test
»» extrapolation, for example IEC 60890.
Neither could be achieved in this case
as there was no evidence of type testing.
AS 60890 could not be used as a method
of calculation. AS 60890 can be used for
verification only if:
»» there are no more than three horizontal
partitions.
»» there is ventilation in the horizontal partitions.
(The standard nominates horizontal
partitions to have 50 per cent ventilation)
»» there are inlet or outlet ventilations. The
standard nominates the outlet to be larger
than the inlet by a factor of 1.1.
Additional requirements of Clause 8.1
While the switchboards inspected did not
have evidence of compliance with subsections
(a), (c) and (g), the other subsections (b), (d), (e)
and (f) of AS/NZS 3439.1-2002 Clause 8.1 are
also required.
Outcome
The switchboard manufacturer volunteered
An example of a 3200amp main switchboard with
no evidence of compliance with AS/NZS 3000:2007
Clause 2.5.5 (not the one referred to in this article)
to remove the non-compliant electrical
equipment and replace it with equipment that
was compliant. They also agreed to pay all costs
associated with the removal, rebuilding, shut
down costs, electrical contractor’s costs and
service charges.
David Webb represents DRC Switchboards.
For further information telephone
(03) 9587 4499.
Consequences:
non-compliant
installations
ESV has the power to:
»» issue a Show Cause Notice
»» issue proceedings under Section 54
of the Electricity Safety Act
»» request a list of all products supplied
»» investigate all products supplied by
a company for a period of up to
three years.