# LOW Voltage



## Wolf (Nov 15, 2009)

I wasn't sure where exactly to put this so if an admin feels it is better paced somewhere else please move it.

So my friend has a recording studio at his house and is that he is only getting 95v from his house hold outlet, and that his console freezes up along with some other issues. I haven't been over to see it but I was wondering if he is correct what could be causing this. Could he be trying to draw too much power? (im not sure that would make much sense....) Thanks for any advice.


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## Les (Nov 15, 2009)

I would think more along the lines of the utility company's distribution transformer or the neutral line in his service panel. Note that if it is the neutral line (either loose or undersized), it could be a huge fire hazard.


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## Anvilx (Nov 15, 2009)

Wolf said:


> he is only getting 95v from his house hold outlet, and that his console freezes up along with some other issues. I haven't been over to see it but I was wondering if he is correct what could be causing this. Could he be trying to draw too much power?



Regardless of the amount of power you are drawing your wall outlets should be giving off 120V (or 240V depending on your location). The load does not impact the voltage, it impacts resistance because I=V/R (Amps=Volts/Ohms) so as your resistance decreases (operating more stuff) your Amperes will increase and vise versa.

Now if he truly is only getting only 95V from the wall i would call a *qualified* electrician ASAP. Fooling around with electricity is dangerous but if there is a problem and you don't even know were to begin troubleshooting it is doubly dangerous.

On an sort of related note about 2 years ago I had a microwave and coffee pot burn out in my kitchen. The electrician who came out check it out and apparently the outlets were reading 240V, twice the norm. I don't remember what the cause was but it was simple to fix simply because he had seen it before, in houses of the same age as mine. Best leave this sort of stuff up to the guys who know exactly what the are doing when safety is on the line.


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## Chris15 (Nov 15, 2009)

Anvilx said:


> Regardless of the amount of power you are drawing your wall outlets should be giving off 120V (or 240V depending on your location). The load does not impact the voltage, it impacts resistance because I=V/R (Amps=Volts/Ohms) so as your resistance decreases (operating more stuff) your Amperes will increase and vise versa.



In an ideal situation this is true. For any practical system it's not. As load goes up, impedance goes down and amps go up. Your power is fed by wire. Wire has a resistance (and an inductance and capacitance we shall choose to neglect for now). So you get voltage drop across your wiring, the magnitude of which is entirely load dependent.

Resistance is proportional to temperature, length and material constant and inversely proportional to cross sectional area. This is why an undersized cable is a fire hazard - that voltage drop we talked about earlier is energy being dissipated as heat. Too much heat in close quarters and you get a fire...

If the volts are low, get a sparky in. It's entirely possible that the distribution transformer needs to be retapped. (More customers have been added on and so the available voltage is now lower...)

Digital or analogue console? Switchmode or linear supply?


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## photoatdv (Nov 15, 2009)

I may be barking up the wrong tree... but wouldn't it be worth a call to the power co? 95V is one heck of a drop from 120... so I'd guess he's not getting 120 at his house...


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## cdub260 (Nov 15, 2009)

Is the problem with the low voltage system wide? Or is it localized to the circuit(s) used for the recording studio?


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## n1ist (Nov 15, 2009)

It could also be the sign of an open neutral, in which case, there's probably a circuit with 145V on it waiting to kill some electonics or cause a fire. In any case, I'd get a licensed electrician to look at things right away.
/mike


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## museav (Nov 16, 2009)

cdub260 said:


> Is the problem with the low voltage system wide? Or is it localized to the circuit(s) used for the recording studio?


I agree, that could be important in assessing the cause. If it is just that line it could be a poor termination or something else related to just that circuit but it if is everywhere then it could be the incoming service. Knowing what the voltage is hot to ground, hot to neutral and neutral to ground might also shed some light.


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## photoatdv (Nov 16, 2009)

If, for example, H-N was 95V, H-G was 120V, would that mean loose neutral? If so would N-G be 25V? Totally just for curiosity .


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## cnote (Nov 16, 2009)

Checking Line-Neutral and Line-Ground on both phases would be a good first start. And easyest place for this is a 230 outlet at the stove or dryer outlets. For the Line Ground check both the outlet ground and to a physical ground. The Cover plate screw usually is grounded.

If you are in doubt about any of this a call to your utility with the symtoms is a good idea. Also ask them what the allowed supply voltage to your is. This should be a range specified by your PUC. Most that I have worked for usually have a 1 or 2 man crew they can dispatch (at no cost, but ask) to check the voltage levels into your home.

Possible causes of low voltage to a single or group of outlets
- The outlet itself is bad.
- Outlets are usually wired in a daisy chain fashion. One of them my have a bad connection
- Breaker bad connection. Either the lead out of the breaker or the actual stab connection the breaker makes with the electric panel

Typically each home outlet is rated for 15 amps and the breaker supplying them is a 20 amp. Nothing loading the line (provided the line have none of the above problems and it is wired per the NEC) could drop the voltage 20 volts (assuming 115 nominal) without tripping the breaker.

With that said I have seen one situaltion where an outlet exibited strange voltage flucuations. It turned out someone needed an extra outlet and tapped off one phase of their 230V dryer outlet to mount the new 115V outlet. 

Please remember that if there is a problem in the home causing this it could be a serious fire hazard.

Above all remember these are leathel voltages. please be safe.

Let use know what the outcome is.


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## tjrobb (Nov 16, 2009)

And then there's my parents' house. Breaker #5, panel #1 (remodel work...) is labeled "Dryer" and is standard 240V, 2-pole. HOWEVER, in the course of adding a dimmer switch I had to drop this (240V) breaker. Turns out it runs the dryer (240), _and 1/3 of a 3600 square foot house - both lighting and outlets._ Don't want to know why it's like this, I just want to fix it.

I won't go into more detail here (to avoid a hijack), but I can easily see how this could be similar to your situation - some bizarre wiring somewhere in the line.


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## SHARYNF (Nov 19, 2009)

As others have mentioned, you need to check to see if this is on all outlets in the house or just that specific outlet. It could be wiring issue in the house, poor connection corroded etc, aluminum wire in copper connection etc etc

If it is all over the house them the likelyhood is a power company problem theyre could be a service entrance problem or an outside transformer issue

sharyn


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## avkid (Nov 19, 2009)

How old is this house?


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## mjw56 (Nov 23, 2009)

anyone correct me if i'm wrong but i there should be 0 volts across the neutral to ground during normal proper operating conditions, and if there isn't, its a problem.

At my job every one in a while when its windy the power dies on one phase and half the office goes dead. we have a long run of overhead wires through woods and fields. the last time a pole mounted disconnect failed and the florescent lights and computers started going crazy because the voltage was flickering all over the place. u would likely see this in other places though as it effects an entire phase. 

opening Panels and disconnects and meter sockets is something ive done under the supervision of an licensed electrician i was working for but would never suggest anyone do it otherwise. alot of safety equipment can be necessary to do things safely. so call an electrician


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## n1ist (Nov 24, 2009)

Under load, you will have a difference between ground and neutral, depending on the load and distance from your service entrance. There's voltage drop in the neutral due to the load current, but there should be no drop in the ground, since there should be no current flowing there.
/mike


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## dramatech (Nov 24, 2009)

A few years ago, I had 90 volts on one hot and 120 on the other. It turned out to be a nick in the wire underground, feeding the house, and allowed the wire to galvanize and partially ground to the earth. The power company repaired the problem by splicing in a new section.
Now the crazy part of this incident, is that it happened to my neighbor about 8 months later and a friend that lived several miles away, another several months.
It seems that the people that buried the cable and the water lines coming from the road were careless, and nicked the cables with their shovels.
A few months later, the galvanizing effect ate through my water line, that was crossing the power line, and I had a geyser coming out of my lawn on halloween night.


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## Anvilx (Nov 24, 2009)

Chris15 said:


> In an ideal situation this is true. For any practical system it's not. As load goes up, impedance goes down and amps go up. Your power is fed by wire. Wire has a resistance (and an inductance and capacitance we shall choose to neglect for now). So you get voltage drop across your wiring, the magnitude of which is entirely load dependent.
> 
> Resistance is proportional to temperature, length and material constant and inversely proportional to cross sectional area. This is why an undersized cable is a fire hazard - that voltage drop we talked about earlier is energy being dissipated as heat. Too much heat in close quarters and you get a fire...
> 
> ...



Dang it! That's physics II I'm only in physics I. Curse You, Science curriculum!


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## Wolf (Nov 24, 2009)

Thanks all for your advice, and this has be interesting to read about so please keep discussing. I've talked to my friend and told him that he should probably call an electrician, I don't want him burning his house down . I'll let you know what the result is if I find out.


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