THE BRIGHTON BRANCH OF A.S.L.E.F.

The train which included this motor coach, was taken over by motorman B.H. Smith, at the Peckham Depot, which it left at 4.17 

p.m., to run empty to London Bridge. Smith stated that he examined all fuses; opened the high tension chamber doors of each 

motor coach, and saw that everything was in good order. He examined the level of the oil in all the-oil switches and found it to 

be correct. He also tested the brakes and the working of the bows of all motor coaches and found them to be in good working 

order. He then drove the empty train to London Bridge and found that it behaved in a satisfactory manner. On arrival at London 

Bridge the two leading coaches were uncoupled, and the remaining six conches were handed over to motorman C. Horsefield. 

No verbal report was given by Smith when the train was handed over, but he conveyed to Horsefield the intimation that all was 

correct by putting up his hand.

Horsefield than worked two double trips between London Bridge and Victoria with this train, and it appeared to be running in 

the usual way. Upon his arrival at London Bridge from Victoria at 6.26, on the last of these trips, he proceeded to reverse his 

bows and to remove the reverser key from the controller in trailer coach No. 4068. The operation of reversing the bows 

proceeded satisfactorily and when Horsefield left this driving compartment they were al in the correct position for leaving the 

station in the opposite direction. Horsefield then pulled up the window of his compartment on the driving side and had just 

begun to walk down the platform when he saw a puff of smoke come from the overhead conductor near the middle motor coach. 

He continued to walk down the train find had walked past two more conches when he heard an explosion, which seemed to 

come from the same motor coach. He thought that there was an interval of some 20 to 30 seconds between these two occurrences. 

On arriving at motor coach No. 3224, one of the brake doors of which had been opened he went in and found that there was still 

a good of smoke. He also noticed a little light under the bottom of the high tension chamber door, which looked at though 

something had fallen and was burning on the floor. He then went to the front of the train to lower the bows, Having done so, he I 

returned towards motor coach 3324, and noticed that the bow on this coach had not dropped, although the two end ones had 

done so. He than went back to the far end of the train and told the Platform Inspector to arrange for the current to be taken off 

the line. Immediately afterwards he met the switch attendant, who told him that this had a1ready been done, and on his return to 

motor coach 3224 he found that the bow had dropped. He opened the high tension chamber door in this coach and observed the 

condition of the gear inside. He then isolated the coach by taking out the jumpers and arranged for the train to be driven to 

Peckham on the other two motor coaches.

Platform Inspector  Milton was on duty on this platform when the accident took place. He noticed that as the bows were being 

reversed and as soon as the centre bow reached the overhead wire, a puff of smoke occurred at the point of contact. He then 

walked towards this motor coach, and just before he reached it an explosion occurred, blowing out a door light on the platform 

side of the motorman’s compartment and scattering the glass on the platform. This explosion he said, occurred some seconds 

after the puff of smoke from the trolley wire. The guard who was walking along the platform with Inspector Milton then opened 

the doors of this compartment on the platform-side. After the arrival of the motorman and his subsequent action already related 

in Horsefield’s evidence, Inspector Milton noticed the bows at both ends of the train lowered, and also observed that the centre 

bow remained in position. A second explosion then took place, and shortly afterwards the motorman again came up Inspector 

Milton said that the second explosion occurred some time after the two end bows had hen moved from the trolley wire. In his 

opinion, the noise of the second explosion was at least as loud as if not louder than, that of the first.. Motorman Horsefield 

however head nothing of this second explosion. Inspector Milton also noticed the light showing under the bottom of the door of 

the high tension chamber after the first explosion.

Guard Hall of the train confirmed  the evidence given by motorman Horsefield and Inspector Milton in regard to this sequence 

of events, but he did not see the initial puff of smoke when the bows were first changed nor did he notice any light under the 

door of the high tension chamber. He gave it, as his opinion that there was an interval of two or three minutes between the two 

explosions, but did not think that the second explosion was as loud as the first, nor did he notice any smoke from the second 

explosion, although there was a considerable quantity from the first.

Guard Cresswell, who was in charge of the train loading up at No.11 platform (that is to say, along side the train on which was 

due explosion occurred), and which was due away at 6.32 p.m., noticed a few minutes before his train \was due to leave a flash 

at the “T”  joint between the feeder and the wire bridging the two overhead conductors running along 10 and 11 platform roads 

respectively. He saw nothing of any other occurrence nor did he hear any explosion.

Station foreman Forster, who was crossing the yard quite close to the far end of the platform, heard, when he was between 8 and 

9 platforms a faint report, to which at the moment he attached no importance. He heard...nothing of any subsequent explosion.

Acting static sub station attendant F. Garman, who was on duty at Peckham Junction Central Switch cabin at the time, gave 

evidence that, at 6.26 pm. S.3 switch tripped. He then inserted a 6 ampere time limit fuse and closed the switch

again after the regulation interval of 20 seconds. The switch then held. At 6 .27 p m .he received a telephone message from 

assistant lineman Tully, at London Bridge Yard Switch Cabin. that. T.1 trolly switch had tripped. Garman then instructed Tully 

to change his fuse and to close so T.I switch. At 6.28 p.m.’S.3 switch again tripped. Garman then told Tully to open and 

subequently to earth T.1 trolley switch. Having heard by telephone from the station staff that the other T.1 switch (that is the one 

in the terminal switch cabin) he also opened. Garman then closed S.3 switch in order to energise the remainder of the group 

section, leaving Nos. 10 and 11 roads isolated. At 6.41 p.m., after Tully had reported that the overhead line was in order, 

instructions were given for T.1 switches to become again. Tully’s report confirmed this evidence, but contained the additional 

information that soon as he closed his T.I switch on Garrnan’s instructions it immediately opened again. 

CONCLUSION

DEDUCTION FROM EVIDENCE

From the foregoing evidence, it is clear that three distinct short circuits to earth occurred between 6.26 and 6.28 p.m.; the first 

resulting in the opening of S3 circuit breaker, set instantaneously; the second opening both T.I. breakers in parallel set 320 

amperes each, with a time log of 11 seconds; and the third opening both S3 switch, set instantaneously, and one of the T.I 

switches set with the normal time lag.

There are very clearly indication of a short circuit in the oil switch an no evidence whatever of short circuiting elsewhere, either 

upon the power or earth side of the switch.

In view of this negative evidence, together with the fact that the main transformer fuses, rated at only 80 amperes, were fond 

intact, it is a safe dedication to assume that  the trouble originated in and was confined to the main H,T, oil switch. The 

possibilities can be further restricted by the fact that the only sign of arcing and break down are to be found in contacts, which is 

not live except when the switch is closed. It therefore follows that all three circuits took place with the main switch closed. 

Further from the indications of heavy fusing on the short switch contacts, it is evident that when this switch did open it was 

carrying a considerable short circuit current; which suggests that the fusing of the contacts occurred when the overload relay 

fuse blew under the overload and so interrupted the main switch holding circuit. It must therefore be concluded that this 

overload relay fuse did not blow until the third and final short circuit, since otherwise the main switch would not have again 

picked up, and contact at which the fault was manifest would not then have been live. The only alternative to this conclusion 

would be the assumption that the fusing of the contacts was so heavy as to cause the switch to stick up against the gravity pull 

off. This pull is, however heavy 25lbs. and, moreover, had this occurred it is highly probable that the contacts would have 

required mechanical separation and that the switch would not have been, as it was, found open after the accident. Finally, all 

three short circuits must have occurred with both S3 and one at least of the two T.I line switches closed.

NATURE OF THE SHORT CIRCUITS

As is perhaps inevitable in a case of this kind, there must be an element of conjecture as to the precise nature and sequence of 

the manifestations. I have, after very careful consideration, come to the conclusion that the facts were substantially as follows:-

The earth fault originated in the cracked insulator of the main H.T. switch. Of the nature and probable cause of this fracture 

more will be said latter. It is highly probable that one or more of these cracks had developed before and possibly several days 

before the train arrived at London Bridge, and that a more or less limited discharge had been taking place through these cracks 

from the surface of the insulator to the casing of the switch. The burning of the wood lining and the grooving of the insulator 

indicate that this discharge had followed indifferently a path along the surface of the oil up the side of the lining to earth, or up 

the surface of the insulator and to earth by way of the lid. This discharge took at first the form of a light resistance leak and 

originated  at the bare end of the contact, running thence between the insulator and the litharge packing, in which there was no 

sign of puncture. The effect of this discharge was to carbonise and vaporise the oil, which had the two fold result of lowering 

the oil level, and by producing a heavily carbonised vapour and sooty deposit, increasing the conductivity of the discharge path. 

Conditions were therefore ripe for a more definite manifestation by the time the train arrived at London Bridge. The first of 

these occurred as the bows were changed, and the probable surge caused by the chattering of the forward and reverse bows 

when this was done resulted in the first definite short circuit, manifested by the puff of smoke, etc., seen by the witnesses, and 

resulting in the opening of 8.3 switch. This did not blow the overload relay switch, mainly, I think, because of its time lag. The 

time lag also prevented T.1, T.1switches from opening. This short-circuit resulted in further and more serious vaporisation of the 

oil, and the charging of the high tension chamber though the oil switch vents with an explosive mixture, whose diffusion may 

well, I think, have been assisted by the very high temperature prevailing. It is probable that this short circuit caused sufficient 

fusing at the contact between the overhead conductor and the bow to result in the latter sticking up when later, the motorman 

actuated the lowering mechanism.