My New Bedtime Read: ASEE Guide To The 11th Edition (July 1939)

[securespark]

Coming across some surprising and interesting stuff.

Window frames, door locks........hooks, brackets, and cleats, clips, saddles and clamps for fixing cables and conduits, need not be connected to the bonding conductor.

Rather the opposite of the bond-mad 15th Edition 40+ years later!


Re Bathrooms:

Wherever practicable, all metal parts of the electrical equipment (other than current-carrying parts) shall be either completely shielded by insulating material or concealed within the walls, floor or ceiling.
Where this is impracticable, the metal parts referred to above shall be permanently and substantially bonded by means of a securely fixed special conductor to other exposed fixed metalwork in the room. This not only includes water pipes and the bath itself (if of metal) but also any exposed gas-pipes.
The bonding conductor may also be used, if desired, as the earth continuity conductor, but a gas-pipe must not be utilised as the earth electrode or earth continuity conductor.

The earthing terminal of every socket-outlet in the room shall be permanently and substantially connected to the special bonding conductor.
The bonding conductor shall consist of either a tinned-copper strip not less than 0.5 inch by 0.02 inch or a stranded tinned-copper conductor not less than 7/.036 inch, which stranded conductor shall be suitably protected from corrosion and mechanical damage.

Given that 7/.036 is bigger than 4 milli, I'm surprised about the requirement for protection from mechanical damage.


Note: The armouring of cables cannot in all cases be relied upon for the purpose of earthing.


1005 (E). The electrical resistance of the earth continuity conductor, including metal conduits, the metal sheathing of cables (other than those used in earth concentric wiring), and the armouring (where an armoured cable has no other metal sheath), together with the resistance of the earthing lead, but excluding the resistance of the earth-leakage circuit-breaker (if any), shall, when measured from the connection with the earth electrode to any other position in the completed installation, not exceed 1 Ohm.

So, there were ELCB's in '39. Didn't know that. And any earth reading must be no more than 1 Ohm. Never mind the extremely long-winded sentence.


1006. .......earth leakage protection........shall be capable of disconnecting the live conductors of the whole installation or, if desired, of only the faulty circuit (or circuits) when the potential between the metal to be protected and earth exceeds 40 volts.
Such earth-leakage protection shall be in the form of one or more automatic devices operating on the existence of a potential between the metal to be protected and earth, or, alternatively, equivalent devices responsive to leakage currents between such metal and earth.
Such automatic devices may, if desired, be incorporated with excess-current protective devices.

Early RCBO's?


1007 (A). Where a water pipe is used as an earth electrode the connection of the earthing lead to such pipe shall be made at the point of entry of the water service into the building.

If this is not convenient, the earthing lead may be connected to the pipe at any other desired position, provided that the pipe has only metal-to-metal screwed, compression or wiped joints, or metal-to-metal bolted flanges (or equivalent), and the resistance measured between any two points of the current-carrying portion of the pipe is such that the potential difference between them cannot exceed 40 volts under fault conditions.

Flexibility about where to attach the conductor to the pipe.


1102. When an insulation test to earth is made of the wiring only (ie before the fittings and switches are fixed) all conductors shall be so connected together as to ensure that all parts of every circuit are simultaneously tested and the insulation resistance to earth shall not be less than 100 megohms divided by the number of outlets.

A new one on me!
The guide then prints the following:

 

[sparkwright]

I didn't realise intermediate light switches were available in 1939.

 

[333rocky333]

Does it mention what the voltage was back then, i was always told it was 250 volt but i think they just said that as it divided easy into 1000 (1Kw) for working out rough load current.
But im sure i used to see old Danger 250v labels on stuff

 

[JohnW2]

1102. When an insulation test to earth is made of the wiring only (ie before the fittings and switches are fixed) all conductors shall be so connected together as to ensure that all parts of every circuit are simultaneously tested and the insulation resistance to earth shall not be less than 100 megohms divided by the number of outlets.
A new one on me! The guide then prints the following: ...

A new one on me, too. However, I suppose it wasn't too bad a
rule of thumb to estimate the extent to which whole-installation IR may decrease with increasing complexity (and increasing cable lengths) of the installation.

Mind you the definition of "outlets" they go on to illustrate is, to say the least, rather 'interesting' !

Kind Regards, John

 

[securespark]

Low voltage is defined as normally not exceeding 250v.

 

[JohnW2]

Low voltage is defined as normally not exceeding 250v.

I've often tried to discover the history of these ('technical') definitions of LV etc, but have never done too well.

If we forget the 'technical definitions' for a moment, the Meriam Webster dictionary gives the current definition (i.e. now) as "voltage low enough to be considered safe for indoor domestic use and typically 120 volts or less", and says the the first use of the term with that meaning was in 1889. However, that presumably is/was US-specific.

Kind Regards, John

 

[securespark]

Yes, I think so.

 

[EFLImpudence]

Window frames, door locks........hooks, brackets, and cleats, clips, saddles and clamps for fixing cables and conduits, need not be connected to the bonding conductor.
Ok. That's good. It does not say except bathrooms; therefore a blanket statement, end of.

HAVE WE FOUND THE FLAW THAT LED TO THE MASS BONDING?
Wherever practicable, all metal parts of the electrical equipment (other than current-carrying parts) shall be either completely shielded by insulating material or concealed within the walls, floor or ceiling. Ok. Insulate exposed-c-ps - i.e. make it so there are no exposed-c-ps. Where this is impracticable, the metal parts referred to above Above??? Surely this just means the uncovered exposed-c-ps. and NOT the parts in the separate paragraph above. After all, no one can consider a door look ever requires bonding. shall be permanently and substantially bonded by means of a securely fixed special conductor to other exposed fixed metalwork in the room. This not only includes water pipes and the bath itself (if of metal) but also any exposed gas-pipes.

 

[securespark]

The 11th Edition (1939): LV normally not exceeding 250V between conductors, subject to such variations as are permissible under the Regulations issued by the Electricity Commissioners.

I don't yet have a copy of the 12th Edition (1950).

The 13th Edition (1955): LV normally exceeding ELV but not exceeding 250V either between conductors or to earth, subject to such variations as are permissible under the Electricity Supply Regulations administered by the Minister of Fuel and Power.

The 14th Edition (1966): LV normally exceeding ELV but not exceeding 250V whether between conductors or between any conductors and earth, subject to such variations as are permissible under the Electricity Supply Regulations, 1937.

The 15th Edition (1981): LV normally exceeding ELV but not exceeding 1000V ac or 1500V DC between conductors or 600V ac or 900V dc between conductors and earth. NOTE- The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerances.

The 16th Edition (BS:7671 1992): LV normally exceeding ELV but not exceeding 1000V ac or 1500V DC between conductors or 600V ac or 900V dc between conductors and earth. The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerances.

The 17th Edition (BS:7671 2008): LV exceeding ELV but not exceeding 1000V ac or 1500V DC between conductors or 600V ac or 900V dc between conductors and earth. The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerances.

The 17th Edition (BS:7671 2008 AMD No. 1:2011): LV exceeding ELV but not exceeding 1000V ac or 1500V DC between conductors or 600V ac or 900V dc between conductors and earth. The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerances, see Appendix 2.

Appendix 2 in this Edition talks about (amongst other stuff) voltage harmonisation and the two stages that have taken place.
Pre 1995, a nominal voltage of 240 with tolerances +6/ -6% and a permitted range of 225.6 - 254.4V.
1 January 1995, a nominal voltage of 230 with +10/ -6% tolerance and a permitted range of 216.2 - 253V

Previous editions do not reference Appendix 2 in the definition of voltages, but the mention of voltage harmonisation in Appendix 2 features in previous amendments of the 17th Edition and in the 16th Edition (BS7671: 2001 AMD No 1:2002 and No 2: 2004) there is even mention in Appendix 2 of a further proposed stage of harmonisation:

1 January 2008 (proposed), a nominal voltage of 230 with +10/ -10% tolerance and a permitted range of 207 - 253V.

This does not appear in the 17th Edition. Nor does Appendix 2 appear in the first BS7671 version of the 16th Edition.

I cannot say what the 18th Edition has; I have not yet bought a copy.

 

[securespark]

Above??? Surely this just means the uncovered exposed-c-ps. and NOT the parts in the separate paragraph above. After all, no one can consider a door look ever requires bonding

Sorry, EFLI...

I have taken chunks of the 11th and put them out of order.

I have re-ordered the texts below. There are still bits omitted, but it is in the order it appears in the book.



1002 (A). ......Wherever practicable, all metal parts of the electrical equipment (other than current-carrying parts) shall be either completely shielded by insulating material or concealed within the walls, floor or ceiling.
Where this is impracticable, the metal parts referred to above shall be permanently and substantially bonded by means of a securely fixed special conductor to other exposed fixed metalwork in the room. This not only includes water pipes and the bath itself (if of metal) but also any exposed gas-pipes.
The bonding conductor may also be used, if desired, as the earth continuity conductor, but a gas-pipe must not be utilised as the earth electrode or earth continuity conductor.
Window frames, door locks........hooks, brackets, and cleats, clips, saddles and clamps for fixing cables and conduits, need not be connected to the bonding conductor.
The earthing terminal of every socket-outlet in the room shall be permanently and substantially connected to the special bonding conductor.
The bonding conductor shall consist of either a tinned-copper strip not less than 0.5 inch by 0.02 inch or a stranded tinned-copper conductor not less than 7/.036 inch, which stranded conductor shall be suitably protected from corrosion and mechanical damage.


1005 (E). The electrical resistance of the earth continuity conductor, including metal conduits, the metal sheathing of cables (other than those used in earth concentric wiring), and the armouring (where an armoured cable has no other metal sheath), together with the resistance of the earthing lead, but excluding the resistance of the earth-leakage circuit-breaker (if any), shall, when measured from the connection with the earth electrode to any other position in the completed installation, not exceed 1 Ohm.

1006. .......earth leakage protection........shall be capable of disconnecting the live conductors of the whole installation or, if desired, of only the faulty circuit (or circuits) when the potential between the metal to be protected and earth exceeds 40 volts.
Such earth-leakage protection shall be in the form of one or more automatic devices operating on the existence of a potential between the metal to be protected and earth, or, alternatively, equivalent devices responsive to leakage currents between such metal and earth.
Such automatic devices may, if desired, be incorporated with excess-current protective devices.



1007 (A). Where a water pipe is used as an earth electrode the connection of the earthing lead to such pipe shall be made at the point of entry of the water service into the building.

If this is not convenient, the earthing lead may be connected to the pipe at any other desired position, provided that the pipe has only metal-to-metal screwed, compression or wiped joints, or metal-to-metal bolted flanges (or equivalent), and the resistance measured between any two points of the current-carrying portion of the pipe is such that the potential difference between them cannot exceed 40 volts under fault conditions.



1008 (D). ..................Note: The armouring of cables cannot in all cases be relied upon for the purpose of earthing.



1102. When an insulation test to earth is made of the wiring only (ie before the fittings and switches are fixed) all conductors shall be so connected together as to ensure that all parts of every circuit are simultaneously tested and the insulation resistance to earth shall not be less than 100 megohms divided by the number of outlets.

 

[EFLImpudence]

Ok.

 

[ericmark]

I remember going as a lad to a place called Llwyngwril in Mid Wales, and they still has a local generator supplying 110 volt DC to houses in the village and local farms.

I know I visited one farm called Pant and in the cellar there was a bank of batteries and other side of the drive there was a generator by time I visited they had mains from national grid so no longer used, however 1939 it would have been still used.

Because of combined generator and battery from what I can work out DC was common, and also 110 volt not for safety but because you needed less batteries.

British Electricity Authority I think started around 1948 I tried to google National Grid but there is now a company with that name, so could not find when the national grid was created, but 1939 reasonably sure each area had its own generator.

As to how many places were on 110, 120, 220, 240, or 250 volt I don't know, but old radios had tapped transformers for user to select supply type, so I suspect it was quite a mixture. I seem to remember mines and quarries had a higher voltage around 480 volt even in 1980 as I know working for SLD pumps we had some pumps for the higher voltage.

I have seen labels 440 volt, so assume that would be 250 volt single phase, but all my life seems to have been 380, 400, and 415 volt. (220, 230, 240). I will guess the 13A socket, and national grid, and 240/415 volt all happened about the same time immediately after the second world war, Llwyngwril changed over when I was a lad, so would say around 1958, but I think it was 19 December 2008 before the last village was finally connected (Abergeirw).

 

[winston1]

When I were a lad around 1950 we were on DC in Barnes SW London. I remember the change over to AC and a "man" coming round and checking all our devices for compatibility and also changing our light bulbs. Some years later when I understood more I asked my parents why the bulbs were changed and they said the voltage was also different and that there was still an old bulb spare in the kitchen drawer. I fished it out and had a look. It was rated at 210V.

 

[ericmark]

I think the problem was there was no standard, I remember 1980 going to Algeria living on camps with generators, if there was a Dutch electrician we had 220 volt if British 240 volt.

Since DC not transformed seems likely the bulb voltage varied depending how far away from generator, I know in Carn-gadell-uchaf farm in Llwyngwril the bulbs were just a red glow not much better than a tilley lamp. Loads of ambiance but not much light.

 

[SUNRAY]

When I were a lad around 1950 we were on DC in Barnes SW London. I remember the change over to AC and a "man" coming round and checking all our devices for compatibility and also changing our light bulbs. Some years later when I understood more I asked my parents why the bulbs were changed and they said the voltage was also different and that there was still an old bulb spare in the kitchen drawer. I fished it out and had a look. It was rated at 210V.

In 70's & 80's I was constructing kit for mobile disco's and tended to use thyristers to switch lights in display units. Being a 1/2 wave device 240V bulbs didn't flash as bright which wasn't really a problem.
One day at work I was looking for something in our local store room and came across several boxes of bulbs, all rated at 210V and the boss said to dump the lot... happy days! I put the word round to other buildings and ended up with a big stash of 210V and 200V bulbs of 15W to 125W, certainly well into the hundreds. I supplied a full set of spares with each unit.

I also ended up with some 70V 25W GLS and 10W SBC golfball bulbs which I used in series for my own kit.