EPoS systems Wiring installation considerations


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


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


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 Power Conditioner

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