Current rails

[programmes1]

I have heard that between Oxford Circus and Piccadilly Circus there are extra current rails? anyone know if this is correct and if so what are they for?

[Tom]

I don't remember anywhere there, between Baker St and Regents Pk SB I do recall an extra out of gauge negative rail though.

[Deleted]

I am not aware either, but there were positive current rails on both sides of the running rails for a distance between Bethnal Green and Mile End many years ago, allegedly (confirmation please?) to prevent or reduce electrical interference with the local hospital's equipment above. I remember them there when I first worked for LT 1965-1967 but have no idea when they were removed.

[ribaric]

Nov 30, 2008 17:01:53 GMT @reganorak said:

I am not aware either, but there were positive current rails on both sides of the running rails for a distance between Bethnal Green and Mile End many years ago, allegedly (confirmation please?) to prevent or reduce electrical interference with the local hospital's equipment above. I remember them there when I first worked for LT 1965-1967 but have no idea when they were removed.

Duly confirmed. It was part of the usual trivia used by road trainers. I have no idea when they were removed although I do understand they made not a jot of difference anyway.

[mrfs42]

Nov 30, 2008 17:01:53 GMT @reganorak said:

I am not aware either, but there were positive current rails on both sides of the running rails for a distance between Bethnal Green and Mile End many years ago, allegedly (confirmation please?) to prevent or reduce electrical interference with the local hospital's equipment above. I remember them there when I first worked for LT 1965-1967 but have no idea when they were removed.

Yes; the installation of these rails is in the yellow peril for the opening of that particular bit of the Central. I typed up the paragraph and it is somewhere in the Central board, I think. I'll have a rummage around and see if I can find a link, without typing it all up again; I don't think from memory that is was the local hospital.

Sssss. No luck with the link; however the germane bit of the peril is (TC 46/1946 Extension of trains to West of Leyton) : also between Mile End and Bethnal Green stations for a length of 1,740 feet in the WB tunnel and 1,800 feet in the EB tunnel the positive current rail is installed on both sides of the track. The site is approximately 690 feet west of Mile End station where the line is in the vincinity of Queen Mary's College.

AIUI the twin conductor rail was more to prevent possible interference with the Physics department. However, there may be some conflation of stories here, as the present physics department wasn't built until 1950 on the site of the redundant St. Benets church.

Twin juice rails would certainly mitigate against stray currents affecting delicate equipment. I'm fairly sure, but open to correction on this, that Queen Mary's college were certainly involved in early reflection high energy electron diffraction experiments for crystallography; plus transmission electron microscopy (TEM). TEM uses a high-energy beam of electrons sped up and steered by an anode and focused electrostatically and electromagnetically. I would imagine that a stray burst of 600v DC from the bowels of the earth would cause the focus to be lost...........

[ribaric]

Twin juice rails would certainly mitigate against stray currents affecting delicate equipment. I'm fairly sure, but open to correction on this, that Queen Mary's college were certainly involved in early reflection high energy electron diffraction experiments for crystallography; plus transmission electron microscopy (TEM). TEM uses a high-energy beam of electrons sped up and steered by an anode and focused electrostatically and electromagnetically. I would imagine that a stray burst of 600v DC from the bowels of the earth would cause the focus to be lost...........

Errr... right! Are you saying that twin +ve rails reduced the likelyhood of arcing in that shoes on both sides of each motor car being in contact with a conductor rail meant that it would be unlikey that all four (opposed to two) would lose contact through the train moving about? There were still only the two -ve though.

[mrfs42]

Essentially, yes. However it's an awfully long time since I've done anything meaningful with electrostatics, so I'll quite freely admit that could be chasing ducks in the long grass here.

What is important to note is that a cast iron tunnel does *not* constitute a reliable Faraday cage.

[Deleted]

Thanks for the info MRFS. My mind was definitely at fault with the "hospital".

[programmes1]

Nov 30, 2008 20:52:59 GMT mrfs42 said:

Nov 30, 2008 17:01:53 GMT @reganorak said:

I am not aware either, but there were positive current rails on both sides of the running rails for a distance between Bethnal Green and Mile End many years ago, allegedly (confirmation please?) to prevent or reduce electrical interference with the local hospital's equipment above. I remember them there when I first worked for LT 1965-1967 but have no idea when they were removed.

Yes; the installation of these rails is in the yellow peril for the opening of that particular bit of the Central. I typed up the paragraph and it is somewhere in the Central board, I think. I'll have a rummage around and see if I can find a link, without typing it all up again; I don't think from memory that is was the local hospital.

Sssss. No luck with the link; however the germane bit of the peril is (TC 46/1946 Extension of trains to West of Leyton) : also between Mile End and Bethnal Green stations for a length of 1,740 feet in the WB tunnel and 1,800 feet in the EB tunnel the positive current rail is installed on both sides of the track. The site is approximately 690 feet west of Mile End station where the line is in the vincinity of Queen Mary's College.

AIUI the twin conductor rail was more to prevent possible interference with the Physics department. However, there may be some conflation of stories here, as the present physics department wasn't built until 1950 on the site of the redundant St. Benets church.

Twin juice rails would certainly mitigate against stray currents affecting delicate equipment. I'm fairly sure, but open to correction on this, that Queen Mary's college were certainly involved in early reflection high energy electron diffraction experiments for crystallography; plus transmission electron microscopy (TEM). TEM uses a high-energy beam of electrons sped up and steered by an anode and focused electrostatically and electromagnetically. I would imagine that a stray burst of 600v DC from the bowels of the earth would cause the focus to be lost...........

Thanks Guys & MRFS I have the Y peril only read the signals sections though, I thought the Bakerloo rails were for some sort of protection don't know of any hospitals above though but it happens elsewhere someone I know works in a building at Holborn when it was being fitted out they had some visitors to see exactly what was going to be used. They were from HMG.

[JR 15secs]

Nov 30, 2008 11:16:49 GMT programmes1 said:

I have heard that between Oxford Circus and Piccadilly Circus there are extra current rails? anyone know if this is correct and if so what are they for?

I have checked some current rail diagrams that I have and these show that between Baker Street and Oxford Circus there were double negative rails, I don't know if they are still there though.