Electric cable history

Thanks. I don't feel so bad now at my previous ignorance of it.

I would have had a stab at the cost (excl. parts) 20 years ago but don't have any idea these days of the all-up costs of labour (i.e. including all the overheads). And there's other data that might be crucial: e.g. whether your MD is a member of the club and wants to be the next captain.

The present JIB rate is £17/18 per hour for an approved spark.

Laxtons calculate overheads at circa 50% on top.

so 34 hours for the sparkies @ £15 = £510

So £600 labour plus profit margin?

Are you sure the actual cable - ie the cable between sockets etc- is cloth covered and someone hasn’t used cloth sleeving in the sockets etc?

Even finding rubber these days must be unusual, although it does happen. I’ve never heard of anyone finding cloth.

I've seen quite a few flexible cables with cloth covering.

yes, to wire them you you had to undo the clear plastic cap and then you grabbed hold of its knob and pulled it out....

That then left an empty back case, and there were terminal screws at the bottom on the inside

Think there were two basic types. One of which varied the on/off by daylight length - for things like shop signs and so on. Clever bit of kit.

Every block of flats in a large estate near here has one to control the hallway lighting.

Bill

The oldest I've seen still in use was in a posh (deputy's) house previously owned by a colliery company. When the successors (the NCB) sold it it was allegedly rewired. However, in the loft I found lengths of timber about 2½" by 1". They had two grooves running their length (as if done by router). Each groove had a bare wire in it, with pitch or tar poured in to fill the groove.

Bill

Roughly - as I have nothing to do with the pricing on jobs.

Probably £200 for the DB and main switch - you buy the main switch separately to the DB depending if you want 3 or 4 pole switching - plus mark up.

Plus the cable tray etc.

I am not sure if moving the defibrillator to it's own circuit was part of the job we did or a separately billed job - but we did that at the same time.

As per the SWA install.

I have told the apprentice he has installed it upside down

Lou's has induction charging - it helps with the IP rating.

Unless Owain beats me to it then Sir Ambrose Fleming has the answer in his Electrical Educator books.

I have the 1931 second edition, I am not sure what edition Owain has.

I'll see what my edition says later.

I am off to the pub and whilst I am there I'll have a pint for TMH who would have been 71 today.

On lamps etc yes. This is a different application.

Brian Gaff has brought this to us :

Where the waxed cotton is taken off, at the ends where they terminate, the rubber tended to dry out and become brittle, the tiny extra bit of heat from terminals might have also played a part.

Aluminium cable was used when the price of copper shot up, usually a size larger than the copper equivalent. Trouble was, it was much more brittle and oxidised. The oxidation in terminals resulted in heat being generated as the resistance increased. Some were copper coated. On really large cables (armoured) the conductors were solid, cable lugs used a grease, to prevent oxidation and heat build up.

Just tell him to rotate it by 180 degrees and then the writing will be the correct way up :-)

Rotate in which axis? as ARW didn't state if he wanted the text to be at the front or back :-)

rotating in z axis would have the text the right way up at the FRONT towards the camera

rotating in x-axis would result in the text being the right way up at the BACK towards the wall

Thanks again. Strikes me as cheap for what I assume was an urgent job. But then I'm inured to inner London prices.

very much. Rubber was rated 60C, it could take far more but didin't last when hot.

But the big difference is the golf course is a 20 minute 7 mile drive from the office and has a big free car park. So there is little travel time or parking to consider.