Overload protection on lighting

[The apprentice]

Hi there, was at a 3 phase DB today doing an EICR with another spark, there was a 10amp mcb with 1x 1.5mm2 PVC twin clipped direct feeding 4 high bay lights via a normal 10 amp switch the other spark then got his note pad out and wrote no overload protection iam say there kind of thinking a mcb protects against overload iam still an apprentice in my last year but I thought it was strange thanks in advance guys ?

 

[telectrix]

maybe his thinking is that the 10A MCB will not protect the 10A switch from overcurrent???

 

[The apprentice]

maybe his thinking is that the 10A MCB will not protect the 10A switch from overcurrent???

Yeah iam just trying to learn a bit more but if it did therefor draw 10 amps would it not trip? But then again it can run at 10 amps for however long therefor damaging the switch ?

 

[Dustydazzler]

Would take considerably more than 10a continues current to burn out a 10a switch

 

[pc1966]

I can't see the issue here. The MCB is no more than the switch, and the cable is going to be at least 10A but any of the usual methods (OSG Table 7.1(ii)), in fact 16A in this case. So for me that is fully overload protected, unless the "clipped direct" cable is in a very hot environment.

If the cable is massively long then it might fail on fault protection (i.e. end of cable Zs not enough to guarantee <= 0.4s disconnection) but unless it is some weird choice like a D-curve that is going to be quite long, at least 52m for B-curve (OSG table 7.1(i) as too lazy at this point to try and compute a length-limit).

 

[The apprentice]

Would take considerably more than 10a continues current to burn out a 10a switch

Thanks mate appreciate it

 

[The apprentice]

I can't see the issue here. The MCB is no more than the switch, and the cable is going to be at least 10A but any of the usual methods (OSG Table 7.1(ii)), in fact 16A in this case. So for me that is fully overload protected, unless the "clipped direct" cable is in a very hot environment.

If the cable is massively long then it might fail on fault protection (i.e. end of cable Zs not enough to guarantee <= 0.4s disconnection) but unless it is some weird choice like a D-curve that is going to be quite long, at least 52m for B-curve (OSG table 7.1(i) as too lazy at this point to try and compute a length-limit).

Thanks a lot mate, that answer has put me on the straight and narrow this is just for my own learning great to get a second opinion from other people ?

 

[DPG]

Thanks a lot mate, that answer has put me on the straight and narrow this is just for my own learning great to get a second opinion from other people ?

Make sure you ask the spark why he made that decision though.

 

[Dustydazzler]

Make sure you ask the spark why he made that decision though.

Exactly

trust nobody , question everything

half the rules and regs I hear banded about by people are nonsense and just made up off the cuff

 

[The apprentice]

Exactly

trust nobody , question everything

half the rules and regs I hear banded about by people are nonsense and just made up off the cuff

A did ask and he said it’s not hot overload protection that’s what a came here to find out from you guys

 

[Mike Johnson]

Just a suggestion, but have a look at the route of the cable to see if it runs through any hot zones.

 

[The apprentice]

Just a suggestion, but have a look at the route of the cable to see if it runs through any hot zones.

Thanks mate was just clipped direct no hot zones what so ever