Electrical engineer looking for practical knowledge

[sunesha sunny]

Hi All,

I am a 26 year old Lighting Engineer with electrical background. As i started my career as a lighting engineer my practical knowledge on electrical aspects related to Industries, building design, Rail traction etc is minimal. I would like to learn more about the same as i am looking for a career change.

Many Thanks for accepting me in electricians forum.

I am looking forward for learning as well as sharing my experience.

Regards,
Sunesha Sunny

 

[Wilko]

Welcome SS ! if you've any questions please feel free to post.

 

[sunesha sunny]

I have one to start with.
It is related to the inrush current and the cable size. I am aware of the fact that a cable would burn off depending on the current flowing through it in a duration of time. Do you have any references to understand the inrush current of different appliances and the preferred cable size depending on the inrush current . My concern is mostly related to LED luminaries.

 

[Marvo]

You wouldn't normally size a cable according to inrush current, cables that are correctly sized according to their installation method and length etc can handle momentary inrush currents without overheating. Inrush current is only likely to have a bearing on your choice of protective device for that circuit ie you may need a C curve MCB to accomodate inrush as long as required disconnect times can still be met.

 

[MODECSOFT]

Welcome Sunesha! You can use our ElectricalOM software for your cable sizing calculations. To download the free version visit electricalom.com

 

[sunesha sunny]

You wouldn't normally size a cable according to inrush current, cables that are correctly sized according to their installation method and length etc can handle momentary inrush currents without overheating. Inrush current is only likely to have a bearing on your choice of protective device for that circuit ie you may need a C curve MCB to accomodate inrush as long as required disconnect times can still be met.

Hi Marvo,

Many Thanks for your reply, so i would probably have to look through the MCB characteristic curves to determine the type of MCB that could withstand the specified inrush current without nuisance tripping. Do you know how the impact would be for fuses? Is the principle same and would require consultation with fuse characteristics?

Regards,
Sunesha

 

[Darkwood]

All fuse types have their own characteristics, not only that but a variation can be evident depending on the manufacturer although the I assume our BS7671 tables are based to lower limit of the independent regulations of device tolerence that manufacturers must comply to.
Most manufacturers do have online pdf sources for their devices and crucially they often give examples of stacked inductive loads ie.. how many lamps of a certain type can be switch on together through a given rated OCPD, you not only have to consider the inrush of 1 device but multiple inrushes if you are switch a bank of inductive lights on.
This can get very complex very quickly but its good to use a manufacterer that provides all these details as it can save a lot of calculation in the design stage.

 

[sunesha sunny]

Many Thanks for your help

 

[sunesha sunny]

Hi All,

Could someone help me to understand the how do we lay cables in a trunking system. Its space factor, and standard trunk sizes available.
How do we take the transition from underground ducts to the trunking system.

Regards,
Sunesha