Old Imperial Singles & Crabtree A15052 Switch

MaintenanceSpark · Dec 20, 2023

Hi guys,

I don’t really know where to post this, sorry if it’s in the wrong place.

After posting a thread about old lead sheathed cable in my attic, Lucien gave me a very good history lesson on the cable which was very interesting and it gave me a big interest in old electrical cables and fittings.

The factory I work in was a WW2 Hospital. We had a bit of quiet time so I decided to check the old conduit systems that are no longer in use but have never been taken down and found runs of old tinned copper Imperial singles. The conduit also led me to an old Crabtree switch that was behind a wall.

The switch was in a poor condition so I decided to restore it. I sandblasted it, painted black and wire wheeled the brass switch knobs and pins.

My question is with the size of cable that was attached to the switch, what power did lights used to draw way back then? (Please see attached photos of the imperial single and restored switch.)

I know Lucien is no longer with us but his history lesson really inspired me to not just chuck things away. So thanks Lucien! The single was also manufactured by the same cable company that manufactured the lead sheathed cable in my attic; Callenders Cables. Shame there’s no date stamp.

DPG · Dec 20, 2023

TraineeMaintenanceSpark said:
Hi guys,

I don’t really know where to post this, sorry if it’s in the wrong place.

After posting a thread about old lead sheathed cable in my attic, Lucien gave me a very good history lesson on the cable which was very interesting and it gave me a big interest in old electrical cables and fittings.

The factory I work in was a WW2 Hospital. We had a bit of quiet time so I decided to check the old conduit systems that are no longer in use but have never been taken down and found runs of old tinned copper Imperial singles. The conduit also led me to an old Crabtree switch that was behind a wall.

The switch was in a poor condition so I decided to restore it. I sandblasted it, painted black and wire wheeled the brass switch knobs and pins.

My question is with the size of cable that was attached to the switch, what power did lights used to draw way back then? (Please see attached photos of the imperial single and restored switch.)

I know Lucien is no longer with us but his history lesson really inspired me to not just chuck things away. So thanks Lucien! The single was also manufactured by the same cable company that manufactured the lead sheathed cable in my attic; Callenders Cables. Shame there’s no date stamp.

That's come up really well that.

timhoward · Dec 20, 2023

That switch looks fantastic, great job!

nicebutdim · Dec 20, 2023

Can't help with the question, but equally I can't help thinking Lucien would be pleased by this turn of events. It's the very reason he wanted to create MEET.

Avo Mk8 · Dec 20, 2023

I agree with all the previous posts, a nice restoration, and I salute you Sir for lining up the screw head slots, which was always the correct way in my younger day. Keep up the good work!

pc1966 · Dec 20, 2023

It is a bit before my time, but the typical home lighting wire in imperial days had only 3 strands (now 1mm/1.5mm style), so seeing 7 probably puts it in the modern 2.5mm sort of territory.

@7029 dave might have something to say about this!

MaintenanceSpark · Dec 20, 2023

Thanks everyone, appreciate it. I had good fun doing it. I'm eyeing up a Bill Talisman cast iron enclosure for the next restoration.

Speaking of that enclosure, could anyone tell me whether the rope looking material on the lid may have asbestos in it?

westward10 · Dec 20, 2023

Being 7 strand you are probably looking at 7/.029 which is a tad bigger than 2.5 in modern terms.

7029 dave · Dec 20, 2023

pc1966 said:
It is a bit before my time, but the typical home lighting wire in imperial days had only 3 strands (now 1mm/1.5mm style), so seeing 7 probably puts it in the modern 2.5mm sort of territory.

@7029 dave might have something to say about this!

Yeah the standard lighting cable in imperial was 1/044 3/029 3/036
eg 1represents the amount of cores after the/ is the conductor diameter size in inches

Cable size	Strand diameter (mm)	Strand csa (mm²)	Total cable csa	Nearest equivalent
1/.044	1.118	0.981	0.981	1
3/.029	0.737	0.426	1.278	1.5
3/.036	0.914	0.657	1.970	1.5/2.5
7/.029	0.737	0.426	2.983	2.5
7/.036	0.914	0.657	4.597	4/6
7/.044	1.118	0.981	6.867	6/10
7/.052	1.321	1.370	9.591	10
7/.064	1.626	2.075	14.528	16

westward10 · Dec 20, 2023

TraineeMaintenanceSpark said:
Thanks everyone, appreciate it. I had good fun doing it. I'm eyeing up a Bill Talisman cast iron enclosure for the next restoration.

Speaking of that enclosure, could anyone tell me whether the rope looking material on the lid may have asbestos in it?

Definitely asbestos.

MJPD29 · Dec 20, 2023

TraineeMaintenanceSpark said:
Thanks everyone, appreciate it. I had good fun doing it. I'm eyeing up a Bill Talisman cast iron enclosure for the next restoration.

Speaking of that enclosure, could anyone tell me whether the rope looking material on the lid may have asbestos in it?

Almost certainly asbestos rope

MaintenanceSpark · Dec 20, 2023

I'll leave it well alone from now then. I have done work in the enclosure before, but haven't touched or disturbed the rope.

I know this will sound naive but are there specialist electricians that deal in the removal of asbestos enclosures?

I'm ashamed to say I've only notice that rope when I zoomed in on the picture, never noticed it once when I was working inside of it. Learning curve for me to be more vigilant I think.

westward10 · Dec 20, 2023

The only people that will touch that are asbestos removal specialists. This is at work so you need to report it to a responsible person.

MaintenanceSpark · Dec 20, 2023

westward10 said:
The only people that will touch that are asbestos removal specialists. This is at work so you need to report it to a responsible person.

I'll report it to my supervisor and the health & safety manager first thing. Thanks Westward.

lozarus · Dec 21, 2023

Looks brilliant! We have the same cable in conduit back in 1963 (some bits still in service) and the same switches, but this stuff would have been used for years before.

I'm glad it's not just me - Lucien spurred my interest and I now have quite a museum myself - and like you often explore behind decommissioned things at work on quiet time just for the interest!

Old Imperial Singles & Crabtree A15052 Switch

MaintenanceSpark

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DPG

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nicebutdim

Avo Mk8

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pc1966

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MJPD29

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