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Help wiring DPST Switch

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Chris Bargman

Mar 22, 2015
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I have this switch: http://www.mouser.com/ProductDetail/Marquardt-Switches/15553108/?qs=4EOvy6wCNnuMsLtaOnPuvA==

I've looked at the datasheet and I just can't seem to figure out how to wire it so that the LED will light up when the switch is in the on position. Most illuminated switched I have used have 3 terminals but this one has four and they seem to only control the devices that are plugged into it.

I have tried every combination of terminals I can think of.

I am wiring it to a 12V DC Source in a car.
 

TeslaCoil

Mar 1, 2016
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This is not the switch you want if you expect it to light up.
I think you'll find it's not an LED but an neon.
The switch is rated at 250v. The light will have a resistor related to that voltage.

Although you could still use the switch for 12v. It will not operate the light.
 
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davenn

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@TeslaCoil is correct in his comments

it will be wired like this .....
as in the Live and Neutral will both be switched

switch.GIF


Dave
 

davenn

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Nice sketch Dave.
But It should be noted that switching the "grounded" conductor (neutral) is prohibited per NEC 404.2(b)

That must be a USA thing
It's pretty standard practice on lots of equip in this part of the world
 

TeslaCoil

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I think what it says is that you shouldn't use the neutral alone to turn off a circuit, however if switching the neutral is combined with switching the live then that is ok. In this case a double pole switch would be fine.

Also, the original request Is about 12v dc, so the NEC 404.2(b) rule does not really apply - although it is still good practice to a switch the live.
 

dorke

Jun 20, 2015
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Nice sketch Dave.
But It should be noted that switching the "grounded" conductor (neutral) is prohibited per NEC 404.2(b)

We shouldn't confuse the Neutral with the Ground.

Ground switching isn't allowed anywhere on earth!
Ground should be permanently connected for safety reasons.

Neutral switching for power applications like electric water boilers etc. is a good practice for safety reasons,
in some places it is mandatory.

Neutral switching for lighting uses is allowed but not always necessary .

and here is the link to that switch datasheet,it clearly shows the electric diagram (mid-right)
 

Bluejets

Oct 5, 2014
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Double pole switching primarily for portable mains powered equipment and things like caravans.
 

Tha fios agaibh

Aug 11, 2014
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We shouldn't confuse the Neutral with the Ground.

Ground switching isn't allowed anywhere on earth!
Ground should be permanently connected for safety reasons.

Neutral switching for power applications like electric water boilers etc. is a good practice for safety reasons,
in some places it is mandatory.

Neutral switching for lighting uses is allowed but not always necessary .

and here is the link to that switch datasheet,it clearly shows the electric diagram (mid-right)

No one said ground. I said:"grounded conductor" referring to Dave's sketch.
Technically it's not a neutral at all. It's a grounded conductor. But many slangly call it a neutral.
Yes, there is an exception to 404.2(b) for disconnecting supply power but I disagree with your assertion that it is a good practice or safer. If the "neutral" were to get disconnected while the hot doesn't (contact fails) it may cause a situation where fault currents will take rogue paths back to its source without tripping a breaker. Also in a multiphase applications loosing the neutral will cause the circuit voltage to change erratically because it lost its reference point. So it is a better and safer in most situations to keep the neutral connected throughout the circuit.
Other than the exception alowing disconnecting a neutral simultaneously or after the ungrounded (hot) for main power purposes, 404.2(b) is, and has been a rule for many years, and for very good reasons.
Btw, the German diagram shows 1 an 2, not L and N

Of course this is not relevant to the op if he is wiring up a car.
But it someone was to want to wire the light switch in their house, it would definitely be a violation.

John
 

dorke

Jun 20, 2015
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John,
Are you talking about a 2 prong power connection?
I'm referring to 3 ,the 3rd being the dedicated ground.

Where do you see ground or anything grounded in Dave's diagram?

Yes the switch uses "terminals 1 and 2" because you can connect it anyway you like.
 

73's de Edd

Aug 21, 2015
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Sir Chris Bargman . . . . . . .


"Although you could still use the switch for 12v. It will not operate the light."


Leaving the . . . . . . illimination at a 12VDC level . . . . . . still withstanding

Thereby:

1 . . . . . Needing to return and get the PROPER unit with its design incorporating an internal LED and its dropping resistor for 12 VDC operation .
2 . . . . .Using the switch that you might now be "stuck with" and the additional mounting of an external LED and its dropping resistor, external of the switch and having the LED "peep" thru a hole just aside to the switch near the rockers "on" position.
3 . . . . .Experiment in the possibility of the drilling of an approximate 1/8 inch hole within the rear backplate of the switch and let the tip of a small, HI intensity LED, dump its illumination into that recess to
flood the inside of the switch in order to illuminate in a power on state.


73's de Edd
 
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davenn

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No one said ground. I said:"grounded conductor" referring to Dave's sketch.

there is no stated ground in my sketch ;)
just live and neutral

anyway Dorke covered the rules which also apply in Oz and NZ
 

Tha fios agaibh

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John,
Are you talking about a 2 prong power connection?
I'm referring to 3 ,the 3rd being the dedicated ground.

Where do you see ground or anything grounded in Dave's diagram?

Yes the switch uses "terminals 1 and 2" because you can connect it anyway you like.
No, I'm talking about the practice of switching a neutral (grounded) thru a switch. Not a 2 or three prong plug.

Ok, your talking about the dedicated ground. And....? (Btw, North America we refer to it as an equipment ground.)

In Dave's diagram he labeled one pole of the switch "N" which refers to neutral. This "N" is an intentionally grounded system conductor (white wire) over here, similar to your (blue wire) common on your side of the pond. It is not the same as an equipment or chassis ground.

I was merely pointing out that in NA (home of op who asked how to wire the switch) It is illegal to switch off the grounded neutral in most instances.

The only reason I mentioned the sketch you posted, is because you said "it clearly shows diagram.." which I interpreted as claiming: switching "N" is alowed as shown in diagram.

Disconnecting or switching a "N" can be just as dangerous as disconnecting an eq.gound. that's why its not allowed per 404.2(b) of the NEC.
 

Tha fios agaibh

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there is no stated ground in my sketch ;)
just live and neutral

anyway Dorke covered the rules which also apply in Oz and NZ
Yes there is. The "N" is a grounded conductor!

Also, it's not a neutral.
A neutral is a grounded reference point between two or more ungrounded (hot) phase conductors.
 

dorke

Jun 20, 2015
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Yes there is. The "N" is a grounded conductor!

Also, it's not a neutral.
A neutral is a grounded reference point between two or more ungrounded (hot) phase conductors.

Like Dave said before,it must be a US thing.
It is invisible to the earthlings on the other side of the pond,sort of a blind spot I guess;)
 

davenn

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Yes there is. The "N" is a grounded conductor!

Also, it's not a neutral.
A neutral is a grounded reference point between two or more ungrounded (hot) phase conductors.

its only grounded at the fuse panel at the house entry

and in most of the English speaking world, its called neutral


please stop arguing !!


Thread closed before it sidetracks further
 
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