Using Type C MCB in domestic propertys

[Brendan.Ashford]

Hi guys and girls.

I am an assistant Electrical Design Consultant and wanted to ask your opinions on a job i have been asked to look at!

We have been asked to look into a latent defect, were a Electrical contractor has installed Type C MCB on the lighting circuit in a number of domestic houses. This has be brought to light from an inspecting electrician, the work is over 3 years old. So this being under the 16th Edition Wiring regulations.

My personnel opinion is that it is good practice to put Type B MCB in on all domestic circuits, but type C MCB's are commonly used for fluorescent lighting in commercial premises and may not trip if a filament (incandescent) lamp ruptures, so this may be why the electrical contractor has done this. i.e health and safety reasons

I say this because:-

Type B MCB trip between 3 and 5 times full load current
Type C MCB trip between 5 and 10 times full load current
Type D MCB trip between 10 and 20 times full load current

I don’t know what the short circuit rating is of the Type C MCB's installed but for this discussion let’s use 6KA.

What are your feelings about it? and can you point me in the right direction with in the 16th Edition Regs book? So i can reference it with in my report!!! Also if an NICEIC inspector is able to give me their opinion I would appreciate it!

 

[DurhamSparky]

Truth Fully speaking nothing wrong with it!!

i brought this up with my Assessment Officer with ELECSA in January and he said Type C are perfectly fine in domestic property's,

only consideration is the size of the cable, he said some thing about 6a type C should be really installed on 1.5mm cable but as long as ZS is met and all test OK no problems..

other than that i think installing type B has just been the norm and accepted as British Way of doing domestic and even some suppliers only make C type as standard in RCBO's


also

just found this

http://www.electriciansforums.net/e...ations/5152-dangers-type-c-domestic-help.html

 

[GStueyXR]

Type C is great for lighting circuits..... Stops the nuisance trips on flourecent start-up..... AND stop the tripouts when halogen bulbs blow.

 

[Deleted member 9648]

As long as the required disconnection time is met for the circuit concerned it can be a bs 60898 type B/C/D..3871 type 1/2/3...3036 semi enclosed...etc/etc...the only consideration as far as Bs 7671 is concerned is disconnection times.
The inspecting electrician is talking out of his posterior.

 

[Brendan.Ashford]

Many thanks to every one who has given their opinion on this subject, you have been a greate help. Now just to turn our words into a report, and refence the regs a couple of times! Job for tomorow i think!