LED indicator lights for DB and panels

[Isetech]

This has become an interesting topic

I use a din rail mount LED for grid and UPS and install a 1 amp fuse inline, just in case.

What is the big deal, fault levels and the ability for the wire to carry that fault if one occurs.

I have builtmany many panels in my time which included panel indicator lights, in most cases they were part of a control circuit protected by a control circuit breaker of fuses.

What size wire do you use to connect the LED indicator light to the circuit breaker, do you install a circuit breaker or fuse to protect the wire for the indicator light.

I also work in places where there are 3000 amp circuits with thin wires feeding off the main bussbar to a meter, protected by a fuse.

What are your thoughts on fault levels, thin wires and indicator lights being used in backup systems?

[Dylboy]

I use the inline fuse for the indicator lights as not always space for a circuit breaker.

Sent from my CPH2197 using Tapatalk

[Justloadit]

I would think, it depends on where the fuse is placed.
If the fuse is placed close to the source, then the fuse will protect the wire to the indicator lamp, in the case the wire gets compromised mechanically after the fuse.
If the fuse is close to the indicator lamp, then it may only protect the wire from the fuse to the lamp if it fails in a short circuit mode.

[GCE]

We generally use a CB in the small DB's under 100Amp

In the bigger DB's you need to get the fuse holder that munts onto the busbar and can handle the fault level otherwise your wire size has to match fault levels - On a 10KA fault level DB your wire size needs to be at least 16sqmm

Rule of thumb is 1sqmm per 1 KA of fault level
Actually thought it was a note in the regulations but I don't find it



6.6.1.13 In a distribution board where the short-circuit rating exceeds 10 kA,
the mechanical strength of the conductors installed between the busbars and
the functional units shall be sufficient to withstand the short- circuit stresses
which could occur. A conductor with a minimum cross-sectional area of
16 mm2 shall be used if it cannot be shown by calculation or from the
component manufacturer's information that a smaller conductor can be
installed

[Isetech]

It our part of the world the max fault level for domestic installation is genrally 2.5 ka, hence the use of 2.5 or 3 ka mcb's

The reason for the fuse and not an mcb is because of the limited space.

The fuse is used between the main switch and the led indicator light. The fault level measured is normally between 260 and 450 amps, so a 0.5 mm wire would be fine and considering ti is in a fault free zones and the chance of it being damaged is literally zero.

I think you got the 1 KA fault level needs to be 16 sq mm and 1 sqmm rule of thumb mixed up ?

We generally use a CB in the small DB's under 100Amp

In the bigger DB's you need to get the fuse holder that munts onto the busbar and can handle the fault level otherwise your wire size has to match fault levels - On a 1KA fault level DB your wire size needs to be at least 16sqmm

Rule of thumb is 1sqmm per 1 KA of fault level
Actually thought it was a note in the regulations but I don't find it



6.6.1.13 In a distribution board where the short-circuit rating exceeds 10 kA,
the mechanical strength of the conductors installed between the busbars and
the functional units shall be sufficient to withstand the short- circuit stresses
which could occur. A conductor with a minimum cross-sectional area of
16 mm2 shall be used if it cannot be shown by calculation or from the
component manufacturer's information that a smaller conductor can be
installed

[Isetech]

This is the LEd, I had my first fail on one of these. I see they yave a PCB in side with an LED. I should check with Onesto to see if there is any built in protection.

https://www.onesto.cn/product/KCI-1L-1007.html


Maybe a terminal fuse might be a better option, then I can use a 2.5 mm from the double pole isolator to the terminal and a 1.5 mm from the fuse to the LED lamp.

[GCE]

We generally use a CB in the small DB's under 100Amp

In the bigger DB's you need to get the fuse holder that munts onto the busbar and can handle the fault level otherwise your wire size has to match fault levels - On a 10KA fault level DB your wire size needs to be at least 16sqmm

Rule of thumb is 1sqmm per 1 KA of fault level
Actually thought it was a note in the regulations but I don't find it



6.6.1.13 In a distribution board where the short-circuit rating exceeds 10 kA,
the mechanical strength of the conductors installed between the busbars and
the functional units shall be sufficient to withstand the short- circuit stresses
which could occur. A conductor with a minimum cross-sectional area of
16 mm2 shall be used if it cannot be shown by calculation or from the
component manufacturer's information that a smaller conductor can be
installed

Thanks Isetech
Yes I left the "0" - should have matched the regulation 10Ka Db needs 16sqmm wire size

[Isetech]

This is what I am trying to understand, how we have 2.5 mm house (prewired at the panels building) inside an 800 amp DB for metering.

Thats why I thought, its just an LED lamp with a bit of electronics to idicate the power is on or off, just like in the LED retrofits, (we had this discussion a while back) I thought a fuse would save the day.

My thought are to make a short bussbar with a fuse attached dirrectly to the fuse holder. I need to make the part that fits into the breaker bigger so so a 4 mm wire flattened and soldered onto the fuse holder will make agood contact in the breaker and offer the fault level protection.