Ancient Supply Cable and Fuse

[Svenedin]

Hello,

I have just joined the forum. I'm not an electrician (I'm a doctor) so please forgive me if my terminology is not correct. I'm starting this thread as I thought it might be of historical interest to some members. Unfortunately I'm not allowed to post pictures yet.

I am going to have some electrical work done at my house and I had an electrician round for a quote yesterday. He had a look at the consumer board and noticed the supply cable coming into the cellar and the ancient main fuse (before the meter). He said that in 30 years of working locally (Croydon, Surrey) he had never seen anything so old. He said I should get on to the supply company and ask for an inspection. I phoned the company and they agreed that they would send an engineer round. The engineer arrived this morning (Sunday). He also said he had never seen anything so old and waxed lyrical about the cast iron head on the supply cable saying they would want it for their museum. Although he assured me it is perfectly safe he said they would replace it tomorrow!

Anyhow, the article in question is a cast iron head on the original supply cable. It is stamped "B I and H C Limited Prescot No. 225" and has the number "2523" in white paint. It also has a lead seal with "B" stamped on it. There is a glass window through which the live and neutral can be seen. The neutral is a thick stranded cable and the live is fuse wire (?100 amp). The cable is thick, bitumen insulated and armoured.

I have discovered that BI and HC is British Insulated and Helsby Cable Limited, Prescot is a town in Lancashire where the factory was. The engineer told me that the lead seal with B on it means blue phase. Presumably 2523 in white paint is the serial number.

Has anyone seen these before (I can't believe they are that unusual)? Does anyone know the approximate date? We think maybe 1910. The house was built in 1902 and was gas lit so it could either have had both gas and electricity at the same time or perhaps the electricity came a little later. I also wonder who might be interested in pictures of this. I expect some people have an interest as there seem to be collectors of almost anything.

Also what does "blue phase" mean? I understand that early electrical supply was not standardised in voltage or frequency. As the house would have been single phase does this mean one of the phases of 3 phase?

Thank you in advance for helping me with my research. we've lived here 34 years and the house still surprises me from time to time.....

Best Wishes,

Stephen

 

[telectrix]

make sure you get some good photos before it's removed. and blue phase is , indeed, 1 of the 3 phases. at your local sub-station will be 3 phase supply. thisis will be split so that you will have, say, 1 street on red, 1 street on yellow, and one on blue.

 

[Svenedin]

Yes I am taking photos now. Trying to take good ones with a tripod and no flash (cellar quite dark). I think the distribution board is original as well (meter and consumer unit are modern). The distribution board is a large varnished wood panel with big screws sitting in ceramic cups. I assume this is so that the screws into the wall are isolated so that they are not a path to ground. We have found a lot of very old (long dead) wiring under the floorboards. All beautifully done; wooden conduit running in notches in the joists with 2 conductors, one red, one black, with ceramic connectors that look like little thimbles (no earth).

We know that our house was the first to be built in the street. There were no other houses until about 10 years later.

 

[Knobhead]

I’ve come across a couple of glass fronted cut outs before. Buxton Derbyshire. They were in buildings supplied from the old three wire DC system.
Would be nice to see a couple of photographs, could you put them on PhotoBucket and link to here?

 

[Svenedin]

I'll try to put them on photobucket as you suggest. Just sorting the pictures out on my computer.

 

[Octopus]

Yes I am taking photos now. Trying to take good ones with a tripod and no flash (cellar quite dark). I think the distribution board is original as well (meter and consumer unit are modern). The distribution board is a large varnished wood panel with big screws sitting in ceramic cups. I assume this is so that the screws into the wall are isolated so that they are not a path to ground. We have found a lot of very old (long dead) wiring under the floorboards. All beautifully done; wooden conduit running in notches in the joists with 2 conductors, one red, one black, with ceramic connectors that look like little thimbles (no earth).

We know that our house was the first to be built in the street. There were no other houses until about 10 years later.

You'll need to do at least 6 posts before you can upload photos!

 

[Knobhead]

The wiring method is called Knob and Tube. Still in use in some American states

And for industrial, how about this

Tel, it isn't my kitchen rewire!

 

[Svenedin]

I don't think it's knob and tube. The ceramic "thimble" bits are connectors and the wires don't run like that. I'll soon have 6 posts and will upload photos.

 

[SPARTYKUS]

The wiring method is called Knob and Tube. Still in use in some American states

And for industrial, how about this

Tel, it isn't my kitchen rewire!

Bet it's your shed in the garden.

 

[monkeyelectric]

The wiring method is called Knob and Tube. Still in use in some American states

And for industrial, how about this

Tel, it isn't my kitchen rewire!

Where is that Tony?

 

[Engineer54]

make sure you get some good photos before it's removed. and blue phase is , indeed, 1 of the 3 phases. at your local sub-station will be 3 phase supply. thisis will be split so that you will have, say, 1 street on red, 1 street on yellow, and one on blue.

More likely this blue phase has been taken off a DNO 3 phase distribution cable. The usual method is to take an alternate phase for each tap off joint, to houses in a street. Sometimes 2 taps are made at each joint one for each side of the road!!


Svenedin,

What you should be looking for is an earth connection to the lead sheath on that old cable, which means the DNO must maintain an earth connection even if it means providing a PME earth!!
If the fuse in question is a rewirable fuse i doubt very much if it is over 60A, very unlikely it will be 80A or 100A.

The DNO have given an undertaking to replace all cast iron service heads with rewireable porcelain fuses by 2011, which they haven't come close to achieving yet!! lol!! They can be extremely dangerous, even too DNO staff, as pulling those type of fuses can break apart/disintegrate in the hand!!

 

[telectrix]

don't forget to reduce the resolution of the photos before posting.

 

[Svenedin]

Thanks Engineer54. I will look for an earth connection to the old cable. I don't think there is one. The earth is bonded to the water main entering the cellar (which is lead and not a very good conductor I believe and if the water company have replaced the main in the street with plastic it isn't going very far...)

Edit: had another look. Can't see an earth connecting to the old cable. I can see an earth very near the old cable which is a surface mounted heavy twisted wire, no insulation, which seems to terminate on a nail in the wall near the entry of the supply cable.

 

[Knobhead]

I got the pictures from a friend in America. Just after I came out of my time I “made safe” a plant ready for demolition. Like a prat I didn’t take photo’s of the main board. that was knob and tube with the knife switches.

This is the only photo I took of a board before I took it out

 

[Engineer54]

Well if that's the case, request a PME earth (if available) when they come to replace the service head and cable. Otherwise you'll need to install a TT system earth (earth rod(s), which in all probability will not give you the protection a PME earth system will give you. You will then be relying solely on RCD's for your earth fault protection as your primary disconnection means!!

 

[Svenedin]

OK. I will ask them.

 

[Engineer54]

And now you should have your 6 posts!! ...lol!!

 

[Svenedin]

First attempt at uploading pictures.


Picture shows supply cable, lead seal stamped "B" (blue phase) and old ? earth cable terminating on what looks like a nail (difficult to see as there is paint on the cable).

Next to the old supply cable is a grey cable disappearing into the hole. This comes from the consumer board. It is not in earth colours but could this be an earth joining the supply cable armour??


Picture of cast iron head "B I and H C LTD No. 225 Prescot"

These were taken on my phone. I will take some better ones on my camera.

 

[Engineer54]

Bloody hell, .... by the look of that fuse wire your up in the 100's of Amps!! lol!! Your fuse and tails look as if they could supply the street!! lol!!

 

[Engineer54]

Just as well that fuse has never blown under a fault condition, it would of taken out that glass panel in a spectacular manner!!! lol!!