Switched receptacle neutral bleed

[Mike Schulz]

I believe this was posted before but could not find it on a search. Hopefully the wording in this title will make it easier in the future.

Inspected a home with several rooms with switched wall outlets. New construction. The top is switched and the bottom stays hot. With my cheap 3 bulb tester the neutral bulb would light slightly like current was bleeding over to it when the switch is off. Now all the rooms where not like this, only a few.

What causes this. I know by speaking with the electrician that the tab was not cut on the neutral side of the receptacle. He claims it's not a problem and it happens all the time.

My question is, why does this happen when the switch is off ?
Since the bulb lights and it's current flowing over to the neutral is it using more power then if its not, by means of higher utility bills. What adverse affects can this have?

Thanks

[Jerry Peck]

With my cheap 3 bulb tester ...

Therein lies some of your problems. ;) (but also not kidding - being truthful)


the neutral bulb would light slightly like current was bleeding over to it when the switch is off.

Current is no bleeding over. I am presuming that you have your night light (your 3 bulb tester ;) ) plugged into the top part which is 'off'.


What causes this. I know by speaking with the electrician that the tab was not cut on the neutral side of the receptacle. He claims it's not a problem and it happens all the time.

Typically, you have 120 volts hot-to-neutral, 120 volts hot-to-ground, and maybe as much as a couple of volts neutral-to-ground (which is nothing to worry about, it is basically just voltage drop across the conductors not quite being exactly the same).

That neutral-to-ground voltage 'could' be lighting it. Those work off sensing static voltage, kind of like a voltage sniffer does. If you take a neon lamp, plug one lead into the hot slot and the neon light will light, even when the other end is in 'free air'.

[Gunnar Alquist]

Mike & Jerry,

I have run into this as well and while I don't know what the cause is, I feel that it is a problem. On a couple of occasions, I have used my volt meter and it registered a significant voltage. Around 60 volts on the one occasion that I can recall. I don't remember if I checked "hot" to ground or just "hot" to neutral, but I know that I did not check neutral to ground. Next time that I run into that, I will try all of the possibilities.

[Eric Barker]

Three light testers are problematic. $2.00 wiggys are better and a good volt meter is better yet. A dim light on my 3-light tester always indicates a problem.

[Gunnar Alquist]

Robert,

I use the "night lights" all the time. However, as has been pointed out on this forum, they can be easily fooled. The (much) more expensive circuit analyzers/testers can test for things like false (bootleg) ground and voltage drop. However, they are not perfect.

[Matthew Barnicle]

I have also run into this phenomenon. After observing a dim light on one of the 3 bulb testers, I put a voltage meter on it and it came up as 20V. I wasn't exactly sure what to call it at the time, I listed it as "phantom voltage" on my report, and referred to sparky. Until I see some documentation that is more definitive, that's what I will continue to do.

[David Banks]

InspectorTools (http://inspectortools.com/surciran1.html)

[Jerry Peck]

Gunnar, Matthew,

What type of volt meter?

If of the digital type, they can read a false voltage from things like that because they have virtually no current draw, however, the old analog meters have enough current draw to draw down a 'static voltage' like that and give a proper reading.

I am *assuming* that there really is nothing wrong ... but Gunnar's 60 volts is a bit high, enough to make me suspect 'something' is wrong someplace.

If you have a SureTest digital, one thing it does is measure voltage and neutral-to-ground voltage, and, being it is performing other tests and drawing current for those tests, I would give its neutral-to-ground voltage reading more credence than a regular digital voltmeter.

[Gunnar Alquist]

Jerry,

Yes, it was digital. Probably Micronta, but I'm not sure. The next time I find a similar reading from my "night light", I will check hot-neutral, hot-ground and neutral-ground with my meter and report what I get.

[John Steinke]

Was the switch of recent manufacture, and did it have "OFF" permanently molded into the handle?

Unless BOTH of those conditions are met, it is very possible that the switch is allowed to let a minor amount of power 'leak' through. This is allowed, so that other things may work - such as illuminated switches.

[Mike Schulz]

New home, typical construction grade (cheap) 3-way switches

[Jerry Peck]

Was the switch of recent manufacture, and did it have "OFF" permanently molded into the handle?

Unless BOTH of those conditions are met, it is very possible that the switch is allowed to let a minor amount of power 'leak' through. This is allowed, so that other things may work - such as illuminated switches.


Switches are fully opened when 'off', no leakage is intended.

Illuminated switches basically have a little neon light in the handle which lights when the switch is off (power is across the switch).

The old illuminated switches were not 'illuminated switches' but rather had a small lamp in the yoke, then, when neon lights came out, those were phased out with the neon lighted handles. Those old switches were also fully opened when 'off', however, the little pilot lamps did draw some current through that circuit, but the older ones were connected to neutral (for the other side of the lamp) and to the hot (like all switches) which was the power to the lamp, still no current flow on the switch leg, though.

At least that is my understanding of how they all worked 'back then' when I was working with them. If anyone has a different understanding, please explain it, I'm always seeking to learn new (and old) things.

[Jerry Peck]

New home, typical construction grade (cheap) 3-way switches

Mike,

You've added a new component to the discussion - "3-way switches" instead of single pole switches.

I can see how a 3-way switch could do that as you have two travelers running from switch to switch, and the voltage on one traveler might ('might') be able to statically charge the other traveler enough to make a neon lamp glow dimly.

[Mike Schulz]

Ohhhhhhhhhh my goodness I spoke to fast with out thinking..........hanging 50,000 christmas lights wears me out.

I'm sorry It was a single pole switch for each room receptacle. Duh

[Joseph P. Hagarty]

New home, typical construction grade (cheap) 3-way switches

I have seen 3-Way switches on Lighting Fixtures. I do not recall ever seeing a receptacle controlled by a 3-Way switch.

[Mike Schulz]

By the way I added a 2-100 amp panels to my existing panels. All exterior outlets with one 20 amp breaker for each receptacle. Guess who wired it............:rolleyes:

[James Duffin]

I would say you have a loose neutral somewhere when you get a voltage reading on a neutral anywhere in a circuit. A neutral should read 0 volts because it is grounded. If the cheap night light works in a properly wired receptacle then goes awry in a faulty receptacle then it has done it's job.

[Jerry Peck]

I would say you have a loose neutral somewhere when you get a voltage reading on a neutral anywhere in a circuit. A neutral should read 0 volts because it is grounded.

James,

Depends on if you are talking about voltage between neutral and hot or voltage between neutral and ground.

Making an assumption that both have similar electrical characteristics, the neutral will have current on it and the ground will not (hopefully will not, anyway), thus, there will be a slight voltage drop across the neutral as compared to the ground, making a slight voltage difference between neutral and ground. A SureTest Digital reads this as one of its tests. I've also made a couple of receptacle outlet tester using three meters, reading the voltage hot-to-neutral, ground-to-neutral, and ground-to-hot at the same time, and with my meters I can also see that ground-to-neutral voltage. On my analog setup it the needle moves just a little, on my digital setup I can actually read the voltage (which is usually in mV instead of V, but I have gotten some readings with a couple of volts, but usually it is very low, i.e., in milli-volts).

Likewise, the neutral-to-hot voltage will be slightly different (lower) than the ground-to-hot voltage for the same reason, that voltage drop across the neutral affects the neutral-to-hot reading by dropping some voltage across the resistor (neutral conductor), the greater the current flow on the neutral, the higher the voltage drop read (not referring to meter current, but to circuit current - say you are checking a small appliance circuit and a toaster is on versus checking the same circuit with a small night light on - it makes a difference in the voltage drop on the neutral.