To avoid these ads, REGISTER NOW!

Switch wiring code question

M

MatBirch

Well-known member
Joined
Oct 10, 2013
Messages
419
Location
Filer, Idaho
I’m about to start pulling new wire into the attic for my knob and tube removal.
I was told that code now requires the home run to go to the switch?? I can’t daisy chain in the attic and just drop a switch leg down to the switch boxes?
I won’t be inspected, but I want to do it right...

Thanks
 
To avoid these ads, REGISTER NOW!
R

rlitman

Well-known member
Joined
Oct 18, 2010
Messages
24,678
Location
Long Island
Code doesn't require the home run begin at the switch. It just requires a neutral in the switch box. So just use 12/3 or 14/3 for your switch legs and you'll be fine.
 
W

wyliesdiesels

Well-known member
Joined
Aug 14, 2012
Messages
20,074
Location
Modesto, CA
MatBirch said:
Ok. Thanks! Then 14/4 for 3way switches?

Should I worry about it in a 115 year old house?
Click to expand...

I haven't looked if it specifically requires neutrals for every switch in multi-switch circuits but i doubt they are excluded. So i would just run it to them. And you can get 14-2-2 NM-b....
 
Last edited:
B

Bert_

Well-known member
Joined
Dec 24, 2016
Messages
9,778
Location
NW Iowa
(2) 14-2's is cheaper than 14-2-2. You're only required to have a neutral at one location for 3 or 4 way switches as I remember.
 
C

cybrdyke

Well-known member
Joined
Sep 9, 2014
Messages
3,449
Location
USA
Connect power to one smart switch and then the others can be wireless. To hell with running wires for 3w and 4w switches.
CD
 
To avoid these ads, REGISTER NOW!
N

n8n

Well-known member
Joined
Mar 11, 2014
Messages
3,607
Location
Curtis Bay, MD
AntonLargiader said:
Interesting. I have to assume the ECG current isn't enough to trip a GFCI. Maybe that's why there's a per-circuit limit.
Click to expand...

Personally I'd put the neutral in for just this reason.

Current code ALSO requires AFCI breakers pretty much everywhere, and those include a GFCI capability. I discovered at my old house that they really work! long story...

Edit: I saw in another thread that someone was saying that their AFCI breakers and those of their neighbors in the same development were giving problems, and others were chiming in saying that theirs worked fine with no issues... my experiences put me in the latter camp, BUT, the house I was living in had no grounds on the 2nd floor except for one room, and no electronic controls - I wonder if maybe fancy lighted or electronic switches were the culprit in that other thread?
 
Last edited:
T

Terry D

Well-known member
Joined
Mar 25, 2015
Messages
2,202
Location
St. Louis, MO.
n8n said:
Right, but the assumption is that the circuit is protected by an AFCI breaker or recep upstream which is also a GFCI.
Click to expand...

I believe what they are talking about in the NEC, at least my understanding, is the amount of current they will allow on the EGC put out by the newer electronic switches, that is why there is a limit on how many can be on a single branch circuit. These newer switches must be designed to not introduce any current on the EGC during normal operation.

As far as GFCI and AFCI protected circuits, they have no reference to ground, nor do they need a ground to operate properly
 
A

AntonLargiader

Well-known member
Joined
Nov 20, 2016
Messages
1,372
Location
Charlottesville, VA
The EGC current represents the current imbalance that will trip a GFCI. It's not that the current is on the EGC, it's that that same current isn't on the grounded conductor. I assumed people would make that connection but maybe not. However, the linked article describes it very well.

To my reading, it looks like it's not about devices manufactured after 2020, it's about installations. After the cut-off date, there will be enough neutral-using devices on the market so you have to wire them to the neutral.

Years ago - like ten years ago - I wired a Lutron Maestro timer or dimmer switch and it didn't work because of the missing neutral. I called Lutron and the guy told me to pull a neutral because I wasn't allowed to send current on the ground. From what I can see on the linked page, this was actually OK until now.
 
Last edited:
T

Terry D

Well-known member
Joined
Mar 25, 2015
Messages
2,202
Location
St. Louis, MO.
AntonLargiader said:
The ECG current represents the current imbalance that will trip a GFCI. It's not that the current is on the ECG, it's that that same current isn't on the grounding conductor. I assumed people would make that connection but maybe not. However, the linked article describes it very well.

To my reading, it looks like it's not about devices manufactured after 2020, it's about installations. After the cut-off date, there will be enough neutral-using devices on the market so you have to wire them to the neutral.

Years ago - like ten years ago - I wired a Lutron Maestro timer or dimmer switch and it didn't work because of the missing neutral. I called Lutron and the guy told me to pull a neutral because I wasn't allowed to send current on the ground. From what I can see on the linked page, this was actually OK until now.
Click to expand...

GFCI's do not care about the EGC, it doesnt need one to work. That is why, by code, you are allowed to put that 3-prong GFCI on a 2-wire system. A GFCI kind of takes the place of a ground, it monitors the current between your ungrounded and your grounded conductors. If the is a 3 to 5 ma difference, it will trip. It doesnt know where it is going, it could be going through a person.

You are confusing grounded ( Neutral ) and grounding ( EGC ) conductors.

I believe neutrals have been required in switch boxes since the 2011 code
 
Last edited:
A

AntonLargiader

Well-known member
Joined
Nov 20, 2016
Messages
1,372
Location
Charlottesville, VA
I am not saying it cares about the EGC. I doubt I actually have to explain this to you but there seems to be some confusion.

Your light is drawing exactly an amp. The GFCI breaker sees that as 1.000A on both the hot and neutral. No problem. Now you put in a smart dimmer that consumes 5mA from the hot and dumps it to the EGC. 1.005A on the hot and only 1.000A on the neutral. GFCI trips. No, it doesn't look at the EGC. But it trips because the 5mA that is on the EGC comes out of the current balance on the conductors that it does see.

EDIT: or to address the discussion better, the dimmer takes 1mA off the hot and puts it on the EGC. One dimmer, no problem. Seven dimmers, the GFCI trips.

That is what I mean. That is what the linked article is talking about.
 
Last edited:
S

sparky 1971

Well-known member
Joined
Oct 9, 2018
Messages
8,018
Location
Central Iowa
A neutral was not required to be installed at a switch if it was possible to fish one in later. This may have changed pre 2020, I have a hard time paying attention in the code update classes after a couple of hours. And since, with new residential construction I have always had a neutral in the switch box, it didn't effect my way of doing things.
 
T

theoldwizard1

Well-known member
Joined
Feb 22, 2011
Messages
43,305
Location
SE MI
IANAE, but I thought the point of the code change was to insure both a "hot at all times" AND a neutral in every box.
 
W

wyliesdiesels

Well-known member
Joined
Aug 14, 2012
Messages
20,074
Location
Modesto, CA
AntonLargiader said:
The EGC current represents the current imbalance that will trip a GFCI. It's not that the current is on the EGC, it's that that same current isn't on the groundED conductor. I assumed people would make that connection but maybe not. However, the linked article describes it very well.

To my reading, it looks like it's not about devices manufactured after 2020, it's about installations. After the cut-off date, there will be enough neutral-using devices on the market so you have to wire them to the neutral.

Years ago - like ten years ago - I wired a Lutron Maestro timer or dimmer switch and it didn't work because of the missing neutral. I called Lutron and the guy told me to pull a neutral because I wasn't allowed to send current on the ground. From what I can see on the linked page, this was actually OK until now.
Click to expand...

Fixed it for ya! :thumbup:
 
You must log in or register to reply here.
To avoid these ads, REGISTER NOW!
Top Bottom