Overhead lines and third rails in depots

[jazzy]

How do electric trains get power in maintenance sheds? Do the third rail / overhead lines extend into the maintenance sheds or do they have to be shunted in? If the third rail / overhead lines extend into the sheds, how do the staff stay safe from them?

 

[swt_passenger]

At relatively new ‘3rd rail’ depots such as at Northam (Southampton), there is no third rail within the buildings. A unit is driven in as far as it can be, (given that the back shoes will still be in contact), and then a dropper cable from an overhead trolley system is plugged into one of the carriage end shore supply sockets. I’ve yet to see photos but that’s how it’s been described to me.

They also have a battery shunter whose main task seems to be manoeuvring units through the wheel lathe building. The few exterior stabling roads there have normal third rail power.

 

[Elecman]

The OLE has interlocked isolating/earthing switches at the feed end of the buildings the interlocking ensures the OLE is off and earthed before the access gates to the above cant line area can be released and these must be proved closed and locked before the OLE can be re energised

 

[aleggatta]

It generally depends on the shed, at Brighton there are berthing roads that have 3rd rail, and pit roads that have overhead trolleys. If you ever want to spy the shore supply socket on a dc electrostar, it’s about chest height when standing on the platform and is a big orange socket with a bar over it blocking it on one of the intermediate ends of a driving coach (it is also electrically isolated from traction when being fed from the shoegear)

 

[edwin_m]

The OLE has interlocked isolating/earthing switches at the feed end of the buildings the interlocking ensures the OLE is off and earthed before the access gates to the above cant line area can be released and these must be proved closed and locked before the OLE can be re energised

There's almost certainly also some sort of system to ensure that nobody is still on the elevated platforms before the OLE can be switched on. For example each worker may have their own padlock to lock the circuit breakers open.

 

[norbitonflyer]

I recall reading that a shore supply was used on the "Standard" (pre 1938) Tube stock on the Underground. There were two fires on trains in service in which short circuits in the shore-supply sockets ("Power receptacle boxes") caused fires.

https://www.railwaysarchive.co.uk/documents/MoT_HollandPark1958.pdf

https://www.railwaysarchive.co.uk/documents/MoT_Redbridge1960.pdf

 

[Andrew1395]

In the old Croxley depot that maintained the Watford Euston DC fleet, there was an overhead powered trolley above each road. A unit was connected by a jumper cable to power it up. The roads were on a slight gradient, and (apparently), it was possible for depot staff to push units into the shed

 

[Merle Haggard]

In the old Croxley depot that maintained the Watford Euston DC fleet, there was an overhead powered trolley above each road. A unit was connected by a jumper cable to power it up. The roads were on a slight gradient, and (apparently), it was possible for depot staff to push units into the shed

My understanding from the time was that here was a problem with this system; when powered up the collector shoes were live. Danger if you were unaware when walking etc at ground level.
Possibly the later systems had wiring that avoided this

 

[edwin_m]

My understanding from the time was that here was a problem with this system; when powered up the collector shoes were live. Danger if you were unaware when walking etc at ground level.
Possibly the later systems had wiring that avoided this

That would need changes on the trains themselves, to add a circuit breaker to disconnect the shoes when connected to the shore supply. On National Rail units running into a shed with power from the shoegear at the rear, the shoes at the front would be live.

 

[cool110]

Also worth noting that there are lights above each road to show if the power is on or off. This is in the Blackpool tramway Starr Gate depot

 

[Tim M]

Zonegreen are a specialist supplier of depot protection systems, based in the U.K., they have also supplied to the export market.

Depot Personnel Protection System (DPPS™) - Zonegreen

Zonegreen's Depot Personnel Protection System, changes fundamentally the way in which the safety of rail depot personnel is achieved and demonstrated.

www.zonegreen.co.uk

 

[Andrew1395]

My understanding from the time was that here was a problem with this system; when powered up the collector shoes were live. Danger if you were unaware when walking etc at ground level.
Possibly the later systems had wiring that avoided this

interesting. It was certainly in use In the 1980s so they mitigated that issue in one way of the other.