Ewhurst Green Technical video Arc-flash Unit (Conductor Rail) Installation.

Technical video on installing an Arc-flash unit for the conductor rail on this DC Southern electric layout.

Arcing occurs when power is being drawn from the conductor rail but the shoe looses contact. It most frequently occurs at conductor rail off-ramps. However, there can be other situations that lead to arcing, such as ice or a broken conductor rail insulator pots leading to a dip in the conductor rail.

On this basis, the arc-flash units ideally need to be installed at conductor rail off-ramps and take account of the direction of the electric multiple units. On a unidirectional track this is relatively straightforward; reversible lines may require arc-units to be integrated with the signalling so they only operate in one direction.

In order to take account of the electric multiple unit's direction of travel, both the track mounted reed-switch and bogie-mounted magnet need to be offset.

This can limit the placement of the reed-switches, particularly at turnouts where conductor rail ramps can be adjacent to wing rails. On the model and in order to obtain greatest visual effect, the arc-units are best situated on the viewing side of the track.

It is worth adding that even with my degraded vision the flash can be easily seen from twenty-five feet away and are most impressive at a slight distance. However, the arc-flash happens so quickly it is difficult to spot the exact spot until one awaits the passing of another electric unit - and not all electric units will be fitted with a magnet!

The 12v arc-flash units were obtained from https://www.layouts4u.net. Their bright LED is almost imperceptibly small so will be difficult to see from a distance.

For 2 BIL /2 HAL units N52 grade neodymium 10mm by 5mm by 2mm magnets from https://www.Magman.co.uk.
15mm by 5mm by 2mm magnets are being sourced for 4 CEP /2 HAP /2 EPB unts to span the gap in the bogie frame.
Caution - these magnets are powerful and should be treated with care - this is also why I'm not fitting them onto powered bogies (with a motor present).

Weathering of the MLV and 2 HAL (etc) undertaken by https://www.themodelcentre.com

Details of Southern Electric units may be found on https://www.bloodandcustard.com/

The Southern Electric was initially powered at 660v (a voltage still used close to joint running section with LUL to prevent unwanted feed-through). However, much now uses 750v and in some locations 850v. However, the voltage on the single-end fed Lymington branch drops to nearer 400v down towards the pier!