Can we also go back to red & black wires please...

[pc1966]

Yeah, the use of cm really annoys me, there are preferred multiples/units.

The other oddity is the deciBel but we can quietly ignore that for now.

 

[Julie.]

let me get a 50cl 1 gill of scotch and i'll re-read that.

Now I understand why people want to move to imperial, a gill is 1/4 of a pint - so around 3x a current 35 - 50ml serving!

And perhaps, really telling tel, is 50cl is 1/2 litre - close on a pint.

So ...

 

[Julie.]

The other oddity is the deciBel but we can quietly ignore that for now.

Yeah odd, but as no one really understands it anyway one can't argue against it....

So when you say it's 10dB bigger that's 10x yes, so the signal is 10x larger?

No that would be 20dB

What, so the power for 10x is 20dB?

No that's 10dB

Err hang on I said that the signal is 10x larger and you said it was 20dB not 10dB

It is yes!

Arrrhhhh....

Now tell me about entropy and enthalpy...

 

[DPG]

Yeah odd, but as no one really understands it anyway one can't argue against it....

So when you say it's 10dB bigger that's 10x yes, so the signal is 10x larger?

No that would be 20dB

What, so the power for 10x is 20dB?

No that's 10dB

Err hang on I said that the signal is 10x larger and you said it was 20dB not 10dB

It is yes!

Arrrhhhh....

Now tell me about entropy and enthalpy...

The logarithmic dB is not that hard to understand once you grasp it. The thing that makes it slightly more confusing to people, I think, is the difference between voltage gain in dBs and power gain in dBs, and also the weighted dBA unit.

I think I'd need a refresher myself to be honest though!

 

[Mike Johnson]

The reasoning behind only using millimetres on construction drawings was it avoids confusion when a dirty finger imprints over the dimension and you loose the decimal point.

 

[pc1966]

The logarithmic dB is not that hard to understand once you grasp it. The thing that makes it slightly more confusing to people, I think, is the difference between voltage gain in dBs and power gain in dBs, and also the weighted dBA unit.

I think I'd need a refresher myself to be honest though!

Strictly speaking the dB is always a power ratio dB = 10 * log10(p1/p2). So the use for voltage gain as 20 * log10 (v1/v2) is avoiding the correct use where the related resistances are factored in. But everyone does it...

All of the others like dBA, dBuV, dBW, dBm, etc define p2 to be something common or useful. OK, not always useful...

And lets not speak of the Neper, shall we?

 

[pirate]

There's 10 types of people...those who understand binary notation, and those who don't...

happy to discuss infer vs imply,or you could just read the book...

 

[Mike Johnson]

Could we discuss the often used "off of"

 

[pirate]

...and "could of" or "should of" UGH!

 

[DPG]

...and "could of" or "should of" UGH!

That really winds me up that. It's almost become normal.

 

[R-fur]

strangely though. D.C. ELV is still red/black, so why is FP200 brown/blue. must be a gender (or some other snowflake fad) thing

DC ELV is not red and black check table 7E of apendix 7 in the book.
Most of the work I do in substations is on DC systems and red and black is never used now. One of the main advantages of the 'new 20 year old' colours is that you can tell from the colours which pole is earthed if any.
Brown and Blue for 110V negative earthed and Blue and Grey for 48V positive earthed. Like wise Black and Black is used for 110V AC circuits which diferentiates them from 240 V circuits in trunkings etc.

 

[Mike Johnson]

Ah "past participles" there is a subject all by itself.

 

[pirate]

perhaps we need a new thread for this stuff, so we can expand on the use of litotes and synecdoche when describing electrical installations

 

[Mike Johnson]

What is the use of talking about this stuff until we are "Black and Blue" or is that "Red and Brown"

 

[Julie.]

DC ELV is not red and black check table 7E of apendix 7 in the book.
Most of the work I do in substations is on DC systems and red and black is never used now. One of the main advantages of the 'new 20 year old' colours is that you can tell from the colours which pole is earthed if any.
Brown and Blue for 110V negative earthed and Blue and Grey for 48V positive earthed. Like wise Black and Black is used for 110V AC circuits which diferentiates them from 240 V circuits in trunkings etc.

I really like the bebs standard numbering for switchgear etc.

You knew instantly what phase, what circuit - whether it was metering, protection, trip circuits, aux etc and roughly where you were in the circuit!
Still got the mustard pamphlet:

 

[Mike Johnson]

@R-fur I read that as "Red and Black Check"

 

[R-fur]

Mike sorry for the lake of comma, I cant even edit the post. I am sure we used to be able to.

 

[DPG]

Mike sorry for the lake of comma, I cant even edit the post. I am sure we used to be able to.

I think you get something like 20 minutes to be able to go back and edit it.

 

[R-fur]

Plus 1 for the BEBS system, Here is a condensed version for anyone that wants it.



Standard Numbering of small wiring

Condensed

Each wire shall have a letter to donate its function. A number identifying the individual wire will follow the letter. Every branch of any connection shall bear the same identification.



Numbering shall read from the terminals outwards on all wires.



Where part of a circuit is common to more than one function, the first in alphabetical order of the appropriate function letters in the table shall be used for the common part.



Circuits having functions not included in the table shall not have prefix letters.



DC positives shall be odd numbered

DC negatives shall be even numbered

Letter	Circuit function	Wire Numbers
A	Current transformers for primary protection, not over current	10-29 red phase 30-49 yellow phase 50-69 blue phase 70-89 residual & neutral 90 Earth 91-99 test windings
B	Current transformers for Busbar protection
C	Current transformers for over current protection
D	Current transformers for metering and voltage control
E	Reference voltage for instruments and metering and protection
F	Reference voltage for voltage control
G	Reference voltage for synchronising
H	AC and AC/DC supplies	1-69 sw gear and generator 70-99 transformers
J	DC supplies
K	Closing and tripping control circuits	Any number from 1 up
L	Alarms and indications
M	Aux control gear	1-19 Sw Gear 20-69 Generators 70-99 Transformers
N	Tap change control	Any number from 1 up
O	Non standard ferruling
P	DC tripping for bus bar protection
R	Interlock circuits
S	DC circuits for control of geny fields
T	Pilots
U	Spare cores
V	Auto switching circuits
W	Light current control
X	Alarms and indications General
Y	Telephones

 

[Mike Johnson]

@R-fur my comment was meant to be humorous not a criticism in any way.