Electrical distribution box?

In summary: GFI receptacle near the light switch, you may find that the GFI starts cutting power to the light even when the switch is off. This is because the GFI looks for an open circuit at the receptacle, and since the light's plug is connected to the live side of the GFI, it sees the open circuit and cuts power.Looking down a branch circuit from the breaker's end, the same assumption should hold true, current in = current out.However there's distributed capacitance in the wiring that bypasses a little bit of current around the breaker's current differencing transformer, so with long lines or electrically "
  • #1
Pain.BH
3
0
In my country, the Electrical distribution box has two sections
lighting section 300 mA
and power section 30 mA

why the lighting section taking more current than the power ?? Shouldn't the power take more ??
 
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  • #2
Hi and welcome.
Those figures don't make a lot of sense to me. Where did you read them? Were they on the RCD (Earth leakage safety circuit breakers?)
 
  • #3
i didnt read them anywhere
all i know that they are using 30 mA for power and 300 mA for lighting and am wondering why 300 mA for lighting ?? isn't that too much ?
 
  • #4
Bearing in mind that 30mA at 240V represents 7.2W, this is very unlikely to be true for any 'Power system'. So when you say that you "know" this fact, I have to ask where you read / heard this and what was the context?
 
  • #5
30/300 mA looks like typical RCD ratings. Why select different ones for different purposes ? Less sensitive ones (higher rated residual current) are cheaper. It also depends on regulations.. in some places highly sensitive protection devices are not needed.
 
  • #6
gerbi said:
30/300 mA looks like typical RCD ratings. Why select different ones for different purposes ? Less sensitive ones (higher rated residual current) are cheaper. It also depends on regulations.. in some places highly sensitive protection devices are not needed.

so in other words they are using 30 ma for power because its more sensitive because power is more dangerous, and 300 ma for lighting because its less sensitive because lighting is less dangerous ??
 
  • #7
Pain.BH said:
so in other words they are using 30 ma for power because its more sensitive because power is more dangerous, and 300 ma for lighting because its less sensitive because lighting is less dangerous ??

Yeah.. sure. LOL. You do not have any EE background, do you ?
30 mA are used for circuits where you (more often) can put your fingers and get hurt.
 
  • #8
gerbi said:
Yeah.. sure. LOL. You do not have any EE background, do you ?
30 mA are used for circuits where you (more often) can put your fingers and get hurt.

I reckon that the standards for lighting circuits (in the UK at least) is so low ( spaghetti of wires, daisy chained all over the place) that 30mA would be quite common for general leakage, in amongst the sawdust, mouse droppings and discarded cigarette stubs. Not to mention the apparent lack of regs about light fittings in general. The build quality of the power fittings is so much better and tighter. To be more charitable, the lifetime of lamps is poor and they frequently take out fuses when they go. This could also cause a hair trigger RCD to cut out, too. (Despite the 'balance' of Live and Neutral currents).
Also, the routing of lighting circuits contains loops of Live conductor to switches and back. Perhaps the unequal Z of some such circuits could be producing a phase imbalance which a 30mA RCD could react to.
 
  • #9
sophiecentaur said:
I reckon that the standards for lighting circuits (in the UK at least) is so low ( spaghetti of wires, daisy chained all over the place) that 30mA would be quite common for general leakage, in amongst the sawdust, mouse droppings and discarded cigarette stubs. Not to mention the apparent lack of regs about light fittings in general. The build quality of the power fittings is so much better and tighter. To be more charitable, the lifetime of lamps is poor and they frequently take out fuses when they go. This could also cause a hair trigger RCD to cut out, too. (Despite the 'balance' of Live and Neutral currents).
Also, the routing of lighting circuits contains loops of Live conductor to switches and back. Perhaps the unequal Z of some such circuits could be producing a phase imbalance which a 30mA RCD could react to.

Well said, +1 from me.
 
  • #10
In theory, all current that enters a healthy device by its supply wire should exit by its return wire. That's the underlying assumption of Ground Fault Interrupters, which i think is what you guys call a Residual Current Device. They operate on the difference between current sent into and current received from their branch circuit.

Looking down a branch circuit from the breaker's end, the same assumption should hold true, current in = current out.
However there's distributed capacitance in the wiring that bypasses a little bit of current around the breaker's current differencing transformer,
so with long lines or electrically "noisy" loads(brushed motor for example) you can get nuisance trips.

I own an ordinary fluorescent shop light with electronic ballast that trips its GFI branch breaker when it tries to startT12 bulbs but with T8's works just fine. I think it generates noise at the same frequency as the GFI's internal electronic IC.

If a well meaning but inattentive handyman messes up your house wiring so that current going out one branch's "hot" returns via another branch's "neutral", well, a RCD simply won't work in either of those two spots.

30 ma probably won't kill a person, hence that choice for residential where tiny fingers may be exploring.
 
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  • #11
http://www.neweysonline.co.uk/RCD/Static.raction

To be effective enough to prevent accidents an RCD should have a tripping current of 10mA or 30mA. An RCD with a trip range of 30mA greatly reduces the risk of heart fibrillation and death. Higher tripping currents are used to protect against fire, in which case the RCD would have an operating current of 100mA or 300mA
.
 

1. What is an electrical distribution box?

An electrical distribution box, also known as a breaker box or electrical panel, is a metal box that contains electrical components to distribute and control electricity throughout a building or structure.

2. How does an electrical distribution box work?

An electrical distribution box works by receiving electricity from the main power source and then distributing it to different circuits and outlets throughout a building. The box contains circuit breakers or fuses that protect the circuits from overloading and causing damage.

3. What are the different types of electrical distribution boxes?

There are several types of electrical distribution boxes, including main breaker panels, subpanels, and fuse boxes. Main breaker panels are typically found in residential homes and have a main breaker that controls all the circuits. Subpanels are additional panels that are connected to the main panel and are used to supply power to specific areas or appliances. Fuse boxes are older versions of distribution boxes that use fuses instead of circuit breakers.

4. How do I know if my electrical distribution box needs to be upgraded?

If your electrical distribution box is old or outdated, it may need to be upgraded. Signs that your box needs an upgrade include frequent tripping of breakers, flickering lights, burning smells, or hot spots on the panel. It is important to have a licensed electrician inspect the box and make any necessary upgrades to ensure the safety of your electrical system.

5. Can I replace my electrical distribution box myself?

It is not recommended to replace your electrical distribution box yourself unless you are a licensed electrician. Working with electricity can be dangerous and should only be done by trained professionals. A licensed electrician will ensure that the box is installed correctly and up to code, reducing the risk of electrical hazards in your home or building.

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