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dfc888
Premium Member
join:2003-07-22
San Bruno, CA

dfc888

Premium Member

[Electrical] Dimmer - blue load wire

I just bought a new z-wave dimmer switch. There is a black (hot), white, blue (load), and green (ground) wire. I thought dimmer switches only have hot, load, and ground.

Why is there a 4th wire?

And what will happen if I reverse the wires (load wire supposed to go to light bulb, but what happens if I accidentally reverse it)? Will I fry the switch???
bbear2
Premium Member
join:2003-10-06
dot.earth

bbear2

Premium Member

[Electrical] Re: Dimmer - blue load wire

For those who are not familiar with the z-wave dimmer switch, it would be helpful if you post the product number or link to spec pages so that they can look it up and respond. A quick look on amazon shows may products with this name.

InsteonFan
@69.245.244.x

InsteonFan to dfc888

Anon

to dfc888
The Zwave, and other smart switches, have computers in them that need to be powered to function.

dfc888
Premium Member
join:2003-07-22
San Bruno, CA

dfc888 to bbear2

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said by bbear2:

For those who are not familiar with the z-wave dimmer switch, it would be helpful if you post the product number or link to spec pages so that they can look it up and respond. A quick look on amazon shows may products with this name.

It is a Linear WD500Z. I am new to these smart switches. Thanks.

Based on the manual, »www.linearcorp.com/pdf/m ··· nual.pdf it seems I can tie in the white and blue wire so as long as I find the correct load wire...?

tschmidt
MVM
join:2000-11-12
Milford, NH
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tschmidt

MVM

said by dfc888:

I can tie in the white and blue wire so as long as I find the correct load wire...?

How did you determine that?

Black (Hot) and White (Neutral) - power the switch. As has been posted they have an embedded microcontroller so need a source of power.

Blue (hot) and White (neutral) provide power to the controlled device.

Green is Safety ground.

If you connect White and Blue together you have created a short and will probably destroy the switch, or at least trip the breaker.

/tom

leibold
MVM
join:2002-07-09
Sunnyvale, CA

leibold to dfc888

MVM

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I don't see that in the manual you linked to.

White must be connected to Neutral to power the dimmer switch.

If you reverse line and load you probably lose the ability to control the dimmer since it no longer gets any power.

Bubba
GIT-R-DONE
MVM
join:2002-08-19
St. Andrews

Bubba to dfc888

MVM

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your existing switch should have two blacks, one is the line(always hot), the other is the load(goes to light)....your new switch black goes to black(line), blue goes to black(load), white to white(nuetral), green to gnd

LazMan
Premium Member
join:2003-03-26
Beverly Hills, CA

LazMan to dfc888

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Another possible wrench in the works...

If the existing dimmer is connect via a switch-leg, you may be SOL... I don't think using the safety ground as a neutral return for 'parasitic' loads is allowed anymore.

Camelot One
MVM
join:2001-11-21
Bloomington, IN

Camelot One to dfc888

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said by dfc888:

There is a black (hot), white, blue (load), and green (ground) wire.

As others have stated, Zwave dimmers are actually devices that require power. Normal switches/dimmers are just interrupter switches, so they only need the line, load, and ground (for safety) It doesn't matter which post the line and load are connected to, because you are just interrupting the electrical path.

ZWave requires power to the switch itself, like any other plug in electrical device, which is why it requires the neutral wire (white). And because it draws its power from the line (black), it DOES matter that you connect the LINE black to the black wire on the switch, and the load (blue) to the black wire running to the light.

Then you just tie all the wire wires in the box together, and tie all of the ground wires together.

I don't know what will happen if you reverse the line and load wires. Best case, the switch just won't work at all. Or the switch itself might turn the lights on and off, but not respond to zwave control. Or it might fry it. Best bet is to figure out which is the line and which is the load, and hook it up right the first time.
Mr Matt
join:2008-01-29
Eustis, FL

Mr Matt to dfc888

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said by dfc888:

I thought dimmer switches only have hot, load, and ground.

Get one of these testers:

»www.lowes.com/pd_464300- ··· cetInfo=

Available at Lowes. You can test for the hot wire with the existing switch off and the circuit breaker on. Probe each terminal on the switch with one probe from the tester while the other probe is connected to ground. When the hot terminal on the switch is contacted by the probe, it causes the tester to illuminate. Use care because the test must be done with the circuit energized. I always wear dry rubber sole shoes when testing live circuits. Make sure you turn off the circuit breaker before you proceed with replacing the switch.

Camelot One
MVM
join:2001-11-21
Bloomington, IN

Camelot One

MVM

I keep one of these around. You don't have to touch the bare wire or mess with a ground. Just get the tip close to the wire (anywhere on the wire) and it will light and beep if there is power.
»www.homedepot.com/p/Klei ··· 03391692

Cheaper AC only version: »www.homedepot.com/p/Klei ··· 00661787

Also very helpful to make sure every wire in the box you are working on is completely off. I have a couple of 3 gangs that get power from different circuits.

dfc888
Premium Member
join:2003-07-22
San Bruno, CA

dfc888 to Camelot One

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I didn't have a dimmer to begin with. It was actually a flip switch that led to an outlet for a light. I just realized this is the old side of the house which still has knob and tube wiring! Great!

Anyway, I might return this zwave dimmer switch and just purchase a plug in AC outlet instead... Less to mess with, and I don't "really" need a dimmer here, anyway...

djrobx
Premium Member
join:2000-05-31
Reno, NV

1 recommendation

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Re: [Electrical] Dimmer - blue load wire

White is neutral. Green or bare wire is safety ground.

There are Z-wave dimmers that don't need neutral, but they usually specify that they only work with incandescent bulbs. I have one and it seems to work fine with both dimmable LED and dimmable CFL.

»www.amazon.com/GE-Z-Wave ··· 06LQFHN2