Receptacle boxes

[Ken H]

I understand EMU's on Southern Region had a socket between carriages where a high voltage DC cable could be plugged in to allow the trains to be moved in depots where there was no 3rd rail for safety reasons, called a receptacle box. (Having a live rail in pitted area would be a real hazard)
These the cable dangled from the ceiling and ran along the shed on some sort of trolley.

I think the London Underground also had/has them

Are they still a thing? and do they exist in depots servicing AC units? (I think not TBH!)

I think there is one in this movie at about 3:34 , on the right

This came up as an idea for perhaps powering preserved EMUs on non electrified lines on this thread - https://railforums.co.uk/threads/preserved-emus-and-alternative-power.237166/

 

[D365]

Yes these ”shore supplies” do exist on units that are DC equipped, or DC capable. E.g. the Class 325s have them, despite having not operated on third rail for 20 years.

Your description of the depot supply system is accurate.

 

[Trestrol]

The NER and LNER Tyneside electrics had them also. The brackets for the wires survived until recently until they demolished South Gosforth running shed.

 

[Dstock7080]

LU still have overhead trolley leads in depots, no longer used by train staff.
Gone are the days of train staff removing 630v leads with no local supply switch.

 

[D6975]

Birkenhead used to have these, but it's an awfully long time since I last went round there..

 

[D365]

Birkenhead used to have these, but it's an awfully long time since I last went round there..

Would imagine that they still have shore supplies, being in the third rail world.

 

[snowball]

If a third rail train is connected to a shore supply, do its shoes become live?

 

[D365]

If a third rail train is connected to a shore supply, do its shoes become live?

No. There is an electrical switch on each undercarriage - where shoes are fitted - that switches between third rail, shore supply or vehicle isolation.

 

[Ken H]

No. There is an electrical switch on each undercarriage - where shoes are fitted - that switches between third rail, shore supply or vehicle isolation.

so an EMU connected to shore supply via receptacle boxes cant have live shoegear, and therefore, cant make the 3rd rail live?

 

[aleggatta]

If a third rail train is connected to a shore supply, do its shoes become live?

This depends on the age of the vehicle. Most modern units have shore supply changeover and shoegear isolation/earthing switches, but older units operate differently.

313/2's and 442's had shore supply receptacles, and traction supply receptacles. When the changeover switch on these units was put into shore supply, the shore supply socket would only energise the auxiliary supplies (compressor and Motor alternator/static convertor). When the shore supply switch was returned to shoegear, and the traction supply socket was used, the shoegear would be energised in this configuration.

Most stuff that operates on AC doesn't have shore supplies, as this is typically simply tied into the DC bus line equipment, and the overhead line is sufficiently out of the way to not be an issue when performing maintenance, with isolations/earthing procedures followed when roof access is required.

 

[D7666]

Couple of comments.

[1] LU stock - when on the overhead trolleys shore supply, the train collector shoes are live - or - at least that is what they tell you when you do depot access training, and I've done 7 different courses for 7 different depots. In workshop areas, that is a significant hazard. TBH I don't know if modern stock like S-stock shoes etc can be isolated, but, 3 of those courses were Neasden Ealing and Upminster post A C D stock elimination and operating S stock only

[2] digressing, some DC depots do have a sort of shore 25 kV AC testing facility. Three Bridges Siemens 700 depot has one road in the 5 road maintenance shed, the nearest road to the Brighton main line with it. It is a 25 kV overhead copper wire running the whole length inside the building; it needs pans up to draw power, but it is a shore supply in the engineering sense, units cannot move under it, it is for static testing and proving auxiliaries on AC. On a visit to 3B depot I did ask what they had in the way of AC test kit - and this was when it was pointed out to me; I have a phot somewhere if I can find might upload somewhere; if I had not asked I would not have spotted it.

 

[D6975]

If a third rail train is connected to a shore supply, do its shoes become live?

When I last went round Birkenhead, the guy taking us round warned us not to touch the shoes on the 508s inside the shed as they were live.

ps this would have been circa 1987

 

[philthetube]

Couple of comments.

[1] LU stock - when on the overhead trolleys shore supply, the train collector shoes are live - or - at least that is what they tell you when you do depot access training, and I've done 7 different courses for 7 different depots. In workshop areas, that is a significant hazard. TBH I don't know if modern stock like S-stock shoes etc can be isolated, but, 3 of those courses were Neasden Ealing and Upminster post A C D stock elimination and operating S stock only

Additionally modern stocks, such as S stock will have an emergence brake application if picking up power from 2 sources, to prevent the wires being pulled down, older stocks did not have this.

 

[CarrotPie]

[2] digressing, some DC depots do have a sort of shore 25 kV AC testing facility. Three Bridges Siemens 700 depot has one road in the 5 road maintenance shed, the nearest road to the Brighton main line with it. It is a 25 kV overhead copper wire running the whole length inside the building; it needs pans up to draw power, but it is a shore supply in the engineering sense, units cannot move under it, it is for static testing and proving auxiliaries on AC. On a visit to 3B depot I did ask what they had in the way of AC test kit - and this was when it was pointed out to me; I have a phot somewhere if I can find might upload somewhere; if I had not asked I would not have spotted it.

Is this what the "AC 25Kv test Compound" shown at Field Sidings (Selhurst Depot) in my Trackmaps book is?

 

[D365]

When I last went round Birkenhead, the guy taking us round warned us not to touch the shoes on the 508s inside the shed as they were live.

I'm surprised that they were never fitted with supply changeover switches.

Additionally modern stocks, such as S stock will have an emergence brake application if picking up power from 2 sources, to prevent the wires being pulled down, older stocks did not have this.

Do LU trains not use a changeover switch? The Class 484s are fitted, but I don't know if this is a new feature for the Island Line.