suitable protective device for light circuts?

[paulthemagpie]

hi peeps,

just looking for some much needed and appreciated help

on an army barracks with roughly 7 to 8 buildings to the installation.

what would be suitable protective devices for the lighting circuts

thanks

 

[malcolmsanford]

Depends on erection methods, whether you need any sort of additional protection, depends on type lighting as to what type of protection, but for me it would be MCB, but the bottom line you will be told by the MOD what to use ........

I don't think they have disintegrated in standards this much to allow design of their installation to be done on an internet forum

 

[paulthemagpie]

hi,

its for an assignment, so its just technically speaking?

so it would just be standard mcb or would it be rcd and cu and then mcb

 

[malcolmsanford]

Back by popular demand ....................my mater soothie

Son look at my post you need to know

1. Erection method
2. Location
3.Type of lighting

etc etc, is there outdoor lighting, how big is the area, how long are the runs, because of the 3% VD for lighting, is it florescent HF lighting, so you need to factor in in rush currents, the list goes on and on son

 

[Amp David]

Are you on commission from this lad Malc if he passes his exams? Think you've pointed him in the right direction for every one of his home study assessment questions LOL

 

[paulthemagpie]

hey, id be willing to pay commission for help! lol

 

[paulthemagpie]

they different lighting amount and types for each disturbution board, most of them are twin florensents but as i say some are not and different amounts all with different runs.

i think its just asking for the typr of protection in general not the actual size so it might just be the mcb with rcd they are talking about! does that make sense or am i well off

 

[Richard Burns]

A suitable protective device would be one that provides a suitable disconnection time in the case of a single fault.
taking into account the installation methods of the wiring for the barracks, the rating of the circuits and the length of the run of cable.
If cables for the lighting are run <50mm deep in walls then additional protection would be needed by an RCD to reduce the risk of electric shock.

 

[malcolmsanford]

you got to pick a pocket or two lads ...................... got to pick a pocket or two ...........................

 

[Strima]

If cables for the lighting are run <50mm deep in walls then additional protection would be needed by an RCD to reduce the risk of electric shock.

True, but barracks can be classed as supervised buildings and would not require RCD protection? Even though squaddies always stick by the rules and never bang nails into walls...

The MOD does not run its own estate management, it's sub contracted to companies such as Sodexo and Supreme. As long as installations fall within the regs the MOD is happy and when it goes wrong it can blame the contractor.

 

[paulthemagpie]

what else could it be apart from the likes of mcbs or rcds or both?

 

[Engineer54]

Are you on commission from this lad Malc if he passes his exams? Think you've pointed him in the right direction for every one of his home study assessment questions LOL

I honestly don't know how these purely home study courses can ever work, they are obviously not giving anywhere near the information required, to fulfill even the simple assignments... At the completion of these courses, if you ever can complete, you would end up having even less idea, than the Electrical Trainee trainees from what i can see.

 

[paulthemagpie]

I honestly don't know how these purely home study courses can ever work, they are obviously not giving anywhere near the information required, to fulfill even the simple assignments... At the completion of these courses, if you ever can complete, you would end up having even less idea, than the Electrical Trainee trainees from what i can see.

hi,

i take on board what you saying but my course is only part home study, i have alot of practical workshops ahead of me. and then after the work shops more training as a mate!

thanks

 

[Engineer54]

It might have been a better idea to of had a stint at the workshop first, to give you a better idea of the practicalities of the course your doing...

 

[Adam W]

I've got nothing against people asking for suggestions but surely the point of a home study course is so that you have a go at it yourself rather than asking on a forum.

Regarding the question it would be a good idea to read through each part of the question - they don't often give you information that you don't need, such as the fact that it's an army barracks. Consider the wiring methods, size of circuits etc and what kind of protection you will need.

 

[paulthemagpie]

im going to go for RCD protection with a type c circut breaker reason being the onsite guide recommends type c for banks of floresent lighting. on one of these building in question it has 50 x 1800mm floresent lighting so i feel thats most suitable.

what do you guys think. am i right?

 

[Richard Burns]

Sounds like you are just about there. 50 fluorescent lamps are going to have quite a current draw on start up so C type sounds justified.
You should consider why you need RCD protection for this circuit. have a look at 522.6.1.101/102.
You would need to justify your selection of these devices as you have done with the C type MCB.

 

[paulthemagpie]

okay, thanks richard!

so it needs RCD protection because of the metallic trunking? is that right

 

[Richard Burns]

No, the metallic trunking would obviate the need for an RCD (assuming it is earthed) as there would be an earthed metallic covering for the circuit.
RCD protection is not required for a lighting circuit even if the cables are run <50mm in a wall if the circuit is for use by supervised people, which one could possibly (sorry me being picky) say is the case in a barracks.

As far as I can tell for your circuit you would not need the RCD just the MCB.

 

[GLENNSPARK]

im going to go for RCD protection with a type c circut breaker reason being the onsite guide recommends type c for banks of floresent lighting. on one of these building in question it has 50 x 1800mm floresent lighting so i feel thats most suitable.

what do you guys think. am i right?

and what else does it say about discharge lamps paul?.....

 

[GLENNSPARK]

try looking on (p) 110 of the osg......look carefully.....then see what it says....

 

[Adam W]

im going to go for RCD protection with a type c circut breaker reason being the onsite guide recommends type c for banks of floresent lighting. on one of these building in question it has 50 x 1800mm floresent lighting so i feel thats most suitable.

what do you guys think. am i right?

You'd have all 50 lights in the building on the same breaker would you?

 

[paulthemagpie]

and what else does it say about discharge lamps paul?.....

sorry you lost me?

 

[paulthemagpie]

You'd have all 50 lights in the building on the same breaker would you?

hi,

thanks for your input, i do really appreciate it.

so i thought the point of a type c breaker was so you could have them all on one breaker?

or should it be split onto like 3 sperate circuts? and if that is the case does this mean we could go with a type class b then or would still a type c be needed

 

[Adam W]

Think about what would happen if the breaker did it's job if all the lights were on it, compared with what would happen if the lights were split into different circuits.
Also carrying out maintenance.
In what situation would you 'need' a type C? All the time?

 

[moehannadnowara]

whats the difference between circuit breakers type b c and d please

 

[davethsparky]

:bigcry:

 

[Dave 85]

Type C breaker allows for high start up current. Type B doesn't
If the barracks lighting is florescent then I would suggest a 10amp C type MCB would be a perfectly suitable protective device in most cases.

 

[davethsparky]

The OP has probably got it sussed by now, it was well over a year ago!

 

[ipf]

whats the difference between circuit breakers type b c and d please

A few pence, maybe.