hb101 retrofit wiring for EPoS systems
Background
A number of customers have asked us to document an approach to the replacement
of poor EPoS wiring in recreational establishments
| The need to re-wire is usually to ensure that the EPoS system is correctly
connected and that no unrelated loads are on the same circuit
Where a site is prone to noise related problems caused by unknown or
unpreventable causes the re-wiring will not necessarily make all the historical
problems disappear. However it does mean that the wiring arrangement is
clearly defined and will not have any earth loops
In addition the provision of both a dedicated line clean earth and the
absence of all earth loops often solves transient noise related problems.
In all cases the current regulations must be observed. The diagram shows
the principles of the new wiring arrangement |
 |
The Spur
The EPoS equipment is generally fed from a single spur protected by an MCB
This spur should be routed around the building avoiding runs close to other
wires - especially high power cables. The wire (conventional twin and earth)
must be sized according to current regulations
The MCB
Type 4 is desirable to allow for the high switch on surges of CVT
types of Power Conditioner
The Earth
The earth is derived from a dedicated earth rod of suitable impedance. NO other
equipment should be attached to this earth.
Care must be taken to ensure no earth loops exist. This can be tested by disconnecting
the earth rod from the spur and checking all gear is isolated from earth
The Power Conditioner (PC)
This will usually be one of two types.
1) CVT based unit with
voltage stabilisation and `bullet proof' noise protection. The CVT
also provides soft start to the load and waveform re-build and well an enhanced
ride-through for mains micro breaks
2) AIT series low impedance conditioner designed to remove ALL common mode
noise
In either case the clean earth is fed to the unit as a safety earth. If a CVT
is fitted the output `low' MUST also be connected to the earth. For the AIT
series this connection is internal
General
It is good practice to ensure that no free sockets are available for non EPosS
loads - kettles vacuums etc.
If for any reason RCCDs are to be fitted they will only protect the load if
installed AFTER the PC
The installer should check the wiring is NOT connected to any other circuit
The system data cabling MUST be checked to ensure that the earth screens are
only connected at ONE end
A diagram of the completed installation MUST be kept to assist further investigation
if problems persist
part of the AEL technical handbook return to hb000
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