Previous Page  68 / 116 Next Page
Information
Show Menu
Previous Page 68 / 116 Next Page
Page Background

68 E L EC TR I C AL CONNEC T I ON

AU T UMN 20 1 7

PATCHING INTO PATCH CORDS

P

atch cords (aka balanced

cords) are proving to be the

weak point in the reliability

of networks.

Irrespective of the quality of a

structured cabling system, poorly

performing and unreliable patch cords

are having a devastating impact on

infrastructure network operations

along with the safety and security

systems that run over them.

The performance obligation for

patch cords goes well beyond just

using appropriate cabling components

to construct patch cords. For example:

>

AS/CA S008 (mandatory), AS/NZS

3080, ISO/IEC 11801 and IEC 61935-2

all have performance requirements

for balanced cords that must be

tested at the time of manufacture.

>

AS/CA S009 (mandatory Wiring

Rules) has a general requirement that

the cabling be ‘fit for purpose’.

>

Telecommunications - Types of

Cabling Work - Declaration 2013

provides an exemption for specific

balanced cords from being deemed

as ‘customer cabling’. This allows end

users to undertake patching while

not breaching any requirements of

the Telecommunication Act 1997 or its

amendments.

>

The draft international standard

ISO/IEC 11801-1 additionally includes

environmental performance

requirements that must be met.

Further, twisted cord performance

requirements currently include but are

not limited to:

>

AS/NZS 3080

>

Return Loss

>

NEXT

>

AS/CA S008

>

Insertion loss

>

Conductor identification

>

Insulation and sheath material

>

Tensile strength and elongation

>

Cord – plug anchorage

>

Flammability

>

UV resistance (if intended for use

external to a building)

>

Conductor composition

>

Electrical withstand voltage

>

Insulation resistance

>

Metallic shield (if applicable)

On-site or workshop manufactured

patch cords are highly unlikely to

meet all AS/CA S008 and regulatory

requirements.

Other factors to be considered

should include environmental

considerations and current-carrying

and heat dissipation capabilities.

(26 AWG and 28 AWG patch cords

may not be suitable to deliver power

to a 95-100W PoE device.)

Poorly constructed twisted pair

patch cords supporting electrical load

switching equipment in a data centre

have been enough to take down the

whole data centre.

Patch cords can be tested in the

field; however, it requires the use of

specialised test adaptors. Channel test

heads are unsuitable for patch cord

testing due to the difference in gating

(associated with the plugs) when

testing a channel and a cord.

So, when specifying patch cords,

the minimum specified requirement

should be based on conformance to

AS/CA S008 to ensure mandatory

compliance, and IEC 61935-2 to

ensure performance compliance and

to help to establish the cords are ‘fit

for purpose’.

> VTI Services

www.vti.net.au

PATCH CORDS ARE AFFECTING

NETWORK AND SYSTEM

RELIABILITY, WRITES VTI

SERVICES TECHNICAL DIRECTOR

MURRAYTEALE

.

Poorly performing and unreliable patch cords are having a devastating impact on

infrastructure network operations as well as the systems that run over them.

NETWORKING