A quick mcb calc for the newbies on here.

[Chr!s]

With a Magnetic Ballasti It would be a 16 amp type C without further information. A 10 Amp type C would suffice for the one.

 

[Darkwood]

With a Magnetic Ballasti It would be a 16 amp type C without further information. A 10 Amp type C would suffice for the one.

Chris ... it seems from your posts your looking to find the deeper aspect of the thread but i did express it was for newbies ...i want to see what the answers will be from their college teaching.. the point of the thread is to show them the reality of a stripped down education that leaves them out of their depth when venturing into commercial and industrial... with your post count and established members on your friends list i would assume this thread isn't aimed at you as you are trying to nit pick every angle ....

Its a standard high bay 400w high pressure sodium nothing different about it the bog standard version with a bog standard ballast and although you yourself haven't hit the intentional nail im trying to put forward on the head its clear your not fresh blood in the industry ...what further info do you need;

I given you the wattage, the lamp type expressed the run is nothing more than 20m and also said we can forget about cable calcs etc ...all i asked was what mcb and type to use on 1x 400w high pressure sodium ...

College teaches you that its an inductive load and is subject to a 1.8 factor

So 400 x 1.8 =720w

college also teaches you an mcb with a type c rating should suffice for a inductive lighting load

so 720w/230v =3.13amps hence a 6amp type C should be ok

I have included the info of loses and control power too soo even with this

2.15amps x 1.8 = 3.87amps would still allow a 6amp type C to be acceptable


IS THIS THE CASE.. ?

 

[Chr!s]

Chris ... it seems from your posts your looking to find the deeper aspect of the thread but i did express it was for newbies ...i want to see what the answers will be from their college teaching.. the point of the thread is to show them the reality of a stripped down education that leaves them out of their depth when venturing into commercial and industrial... with your post count and established members on your friends list i would assume this thread isn't aimed at you as you are trying to nit pick every angle ....

Not nit picking, just the way i was taught.

Its a standard high bay 400w high pressure sodium nothing different about it the bog standard version with a bog standard ballast and although you yourself haven't hit the intentional nail im trying to put forward on the head its clear your not fresh blood in the industry ...what further info do you need;

No im fresh blood, well in this game anyhow, thats why i answered

I given you the wattage, the lamp type expressed the run is nothing more than 20m and also said we can forget about cable calcs etc ...all i asked was what mcb and type to use on 1x 400w high pressure sodium ...

Well, the cable's do play a part in determing the MCB, especiallyl on large banks

College teaches you that its an inductive load and is subject to a 1.8 factor

So 400 x 1.8 =720w

college also teaches you an mcb with a type c rating should suffice for a inductive lighting load

so 720w/230v =3.13amps hence a 6amp type C should be ok

I have included the info of loses and control power too soo even with this

2.15amps x 1.8 = 3.87amps would still allow a 6amp type C to be acceptable


IS THIS THE CASE.. ?

the Clue is in the capital :wink_smile:

Its not the way i was taught.

 

[Darkwood]

the Clue is in the capital :wink_smile:

Its not the way i was taught.

Exactly ive had many apprentices and their are all singing from the same hymn sheet which is stripped down so much they are ill prepared for the real world (except house bashing)... i confronted a lecturer recently and expressed my concerns and he said that all the design side is part of a optional extra course..... ' In my tuturing i couldn't be classed as an electrician unless i knew this stuff'

Exactly!... he replied 'im sometime embarrased at the lack of acheivement level needed nowadays to be called an Electrician'

Im slightly disturbed to say the least....

Having said that, ive got loads of work of the back of these ill educated sparks ..just a shame as its not really their fault.

 

[Chr!s]

What ive learned has been from wanting and not from college, as you say you would be out of your depth in the comercial and industrial world.The course's are far to thin on the ground, even the 2391 02 is thin on the ground.

 

[Chr!s]

We have 5 230 V high pressurer sodium light's 400W each. The Displacement Power Factor is 0.9, Capiatance of each Fitting 22.5 uH, PFC(Isc) at fitting is 338 Amps

Whats the ;

Total Active Power?
The Apparent Power?
Total RMS Current?
Peak Current?
Total Capitance?
The Line Inductance?
The Peak Inrush Current?
What Sizeand Type Breaker Is Required?

All the Info is there

 

[ian.settle1]

Darkwood are we having a slight go at Electrical Trainee here?:detective::willy_nilly::nono:

 

[Darkwood]

@chris.... il have to dig out my notes on that its been a while since ive entertained those calcs...lol
@ian.... actually not at all its a dig at the stripped down college systems for full 2-4yr courses ive been finding over the last several yrs the pass grade has been relaxed and content is basic at that....

This is going to have consequences in the long term as we are already saturated with domestic level Electricians and as mentioned Electrical Trainee's ...this is seeing a shortage of skilled electricians in commercial and industrilal design an due to their been a lack of work domestic alot are taking a very big step to earn a few quids in areas they just weren't taught to understand or competent to do. I coming across it more and more now with problematic installs been down to poor design.
It beggers believe they can grade someone an electrician without them been able to design larger installs..

Im hoping that they will just put domestic rated Electrician as a grade for all college leavers and further education requirements for commercial and industrial .... the colleges win with extra money for courses, the industry wins with higher standards achieved the only losers are those trapped in the saturated domestic side all trying to cut corners to win quotes.

 

[Engineer54]

Bring back the old 2360, (before even that got watered down!!) lol!! No multiple choice questions, an exam where you needed to KNOW and be able to explain the answers, or you failed!! ...lol!!

 

[Baker1988]

Bring back the old 2360, (before even that got watered down!!) lol!! No multiple choice questions, an exam where you needed to KNOW and be able to explain the answers, or you failed!! ...lol!!

Well that is how the new 2357 is there is about 5 tests for each unit and only one of them are multiple guess tests the rest are short answer tests with a 100 percent pass mark so you can not get even 1 question wrong and there a lot more difficult.
I am now just starting the selection and design side of the installs with all the proper cals and our tests are designed around industrial installs not domestic

 

[Knobhead]

Bring back the old 2360, (before even that got watered down!!) lol!! No multiple choice questions, an exam where you needed to KNOW and be able to explain the answers, or you failed!! ...lol!!

What happened to C&G's with a name? Mine was from the Union of Lancashire and Cheshire Institutes. C&G appears as an after though.

 

[Silly Sausage]

I've forgotten more than you lot have ever learnt. hahaha
And what good did it do me........

 

[i=p/u]

its the way i was taught if you dont know factor use 1.8

 

[Badged01]

Darkwood -- so what was the actual practical solution to the problem based on your knowledge and experience of real-life installs?

Have to say I've always installed to the type 'C' 1.8 factor rule and never experienced any issues. Then again that has always been for light commercial applications (shops etc ..... ) and not heavy industrial.

 

[Darkwood]

Thanks for asking for the solution well il attept to answer... When using inductive loads especially multiple loads that share the same MCB and are subject to striking together then the first port of call is manufactures guidelines (tables or by direct enquiry)... subject to their advice on the mcb rating required to eliminate all chances of nuisance tripping will have a great bearing on the design of the install especially csa of conductors.

The 400w high pressure sodium has no specific answer for mcb rating but choosing the mcb to protect it then i can give you a sample answer;

Merlin Gerin C60 range of 60898 recommends a 6amp(c) which is within the normal thinking channels but if you have 2 x 400w then its a 10amp.

Square D KQ range of 60898 recommends a 10amp(c) for one 400w fitting and a 16amp for 2 x400w

Hopefully you can see that not knowing the manufacturers mcb's characteristics with a particular inductive load whether it be a motor, transformer or lamp(s) etc can make your standard teachings for designing a circuit and sizing a cable wrong, the colleges are in the habit of teaching you a rule of thumb method and when you progress from a domestic or small commercial situe you can quickly find your installs having issues of tripping and the only to rectify it would be a increase in cable size to allow for the correct mcb according to manufacturers.

This is my beef with the dumbed down system its been stripped back so much (not the students fault) that they are ill prepared and are still rubber stamped with the term electrician although they could not effectively work out what correctly what would seem a simple circuit, going by college a 400w hp sodiums = 3.13amps- a 6amp (c) mcb but Square D KQ range specifies a 10amp whereas Merlin agrees with the 6amp rating.

Ironically both Merlin and Square D are made by the same manufacturer 'Schneider' ...now the examples i have shown are to emphasise the issue but as the inductive trait of the load increases i.e. a large motor then the standard teaching become more problematic... ive seen so many installs designed as taught where the mcb trips from a standard inrush and upgrading the mcb to suit the job would require the cable to be upgraded.