series & parallel

[Patto]

I'm on second year of my 2330 at college on a night course but Im just wanting a bit of help understanding were these circuits would be used and why they would whats the benifits of either, I can do the calcs, I like to be able to visualise things in the real world not just be told about it in a lesson, can anybody shed some light ( no pun)

Thanks in advance

 

[MDJ]

tell us what you think series and parallel are concerning circuits, what are christmas tree lights wired in?

 

[Silly Sausage]

... what are christmas tree lights wired in?

That crappy green twisted stuff that turns into a rats nest.

 

[Patto]

Xmas is series hence one goes they a'll go

 

[MDJ]

okay good start, now explain how they are wired

 

[Patto]

What I mean is I would wire up say a garage with fluros from my switch then to the next light and so on I would say there then in series? But how would you wire in parallel

 

[Patto]

Xmas lights I would think it's a case of the cable goes to a lamp through the lamp on to the next lamp and so on so if the first one goes down the circuit cannot be completed hence lights out.

 

[MDJ]

No you would never wire fluorescents in series, they would never work, think about it, think about how christmas tree lights are wired and where the cores connect then think about your garage light circuit and where the cores connect there? you will get there.

 

[Patto]

The cores are connected to the bottom of the lamp? So therefore it needs to be intact for the circuit to be complete so if one element is broken its an open circuit?

 

[Patto]

Fluros that are "daisy chained" I'm thinking by taking a feed to the first light then out to the other one and so on would be paralell due to it not using the light as its path to the next one?

 

[dim_bulb]

What about the workshop with emergency stop buttons?

 

[Patto]

Not sure I would think they would be in series so that the emergency stop would isolate every think connected

 

[MDJ]

well your wording may not be perfect but you are getting there and pretty much correct, if you imagine a circle and cut into the circle several times and add a lamp into the cut you have a series circuit, if one lamp blows there is a break, and basically that is a christmas tree circuit and a series circuit, as for parallel, if you took a live wire and neutral and looped several lights in a row, even if one stopped working the others would still work because the lives would be joined one side of the lamp and the neutral joined together the other side of the lamp, the circuit would still be intact as the conections would still be made even if the lamp was blown, the wires would still have continuity as they are joined together and not joined via a lamp.

 

[Patto]

That's great thanks for that, so final rings and radials are in parallel then I'm thinking

 

[MDJ]

definately not in series

 

[Patto]

Again thanks for that, good way to get my mind thinking as opposed to giving me the answer, it's good to be able to chew it over with someone that actually knows if what I'm thinking is right or wrong

 

[PRR]

> wire up say a garage with fluros from my switch then to the next light and so on I would say there then in series? But how would you wire in parallel

Slit the cable/conduit, pull all the individual wires out, spread them around the floor so you can see what's really happening.

(I have a picture but I'm too new, maybe you can find it? i.Upload the image directly to the thread.com {slash} 5H4yb.gif )

Switch and lamp(s) are in Series.

All switch+lamps strings are in Parallel across the power source.

In general you "never" have loads (lamps, heaters, toasters) in series. You buy a load to suit your local voltage. 230V lamps in 230V districts.

A special-case may illustrate. Say you have 230V supply but somehow you got a big box of 115V lamps. You could wire two 115V lamps in Series across the 230V supply and (if identical) they work fine. (Until one blows, of course, and you have to find which it is.) "Fine" electrically-- the wire between the two series lamps is a gray-area in building wiring rules because you just never do things this way.

> 2330 at college

School work must cover many more things than are found in a garage. Obviously you do have Series in the form of switch & lamp, though mainly everything comes out Parallel. However in Electronics we sometimes have long strings of series resistors (or other parts) to sub-divide an available voltage into smaller voltages. You need to do all those problems in the book to get foundation for further study.

Special Case: Voltage Dividers. Nearly everything can be reduced to a voltage divider and some insight gained. The switch plus lamp series string has two conditions. Lamp is (say) 100 ohms. Switch can be 0.1 ohms "on" or 500Meg (million) ohms "off". When "on", the division ratio is 0.9999... the lamp gets 229.8V and the switch gets 0.23V. The lamp runs bright. When "off" the division ratio is 0.000,000,2.... lamp gets 0.000,05V and switch is blocking 229.999,95V. While this example is near-enough "on/off", 100 and 220 ohms divider makes more interesting results and (with different numbers) is found everywhere in electronics.

> Xmas is series

Many are. Series uses less wire. Low-power high-voltage lamps are tricky. Series-stacking 12V lamps up to line voltage is cheaper. Also: one failure forces repair. If the string is both dead and tangled, many users will ---- it aside "for later" (never) and go buy another string. A very merry Xmas for the stores and factories.

There are parallel strings but they cost more and are going out of style.

> would never wire fluorescents in series

There is a special case for huge installations. Many tubes wired in series on one ballast from a HIGH voltage line. It is certainly not common; because of danger and also because other light sources compete better in huge jobs. It's the kind of thing Patto *might* run into in a textbook.