Is excessive Voltage Drop a safety issue?

[StevenSmart2]

I have an installation where existing feeders have been installed without regard to Voltage Drop. In some cases the voltage drop is so bad that a 120V single phase circuit will measure 80V when loaded. The circuits have correctly sized circuit breakers on them.

There are a few permanently installed motors (for door openers), the other loads consist of:
- Incandescent lighting.
- Fluorescent lighting.
- Plug in power tools (drills, air-compressors).

I can see that motors will be prone to burning out.

Are there other risks?

And the final piece of the puzzle- this is a non-profit group whom I would like to help, and they have no funds to upgrade the existing installation.

The Electrical Inspections department seem to be suggesting that they will not require the existing installation to be upgraded.

Thanks.

 

[DanDel]

I would imagine the lighting issues at least would be a safety hazard.
I'm curious how the feeders were installed to cause such a voltage drop, just from extremely long runs? Undersized transformers?

 

[ykee]

What size are the feeders? Are the terminations good? Are all circuit having the same voltage drop?

If you have a voltage drop, something is heating up somewhere, which could be a problem.

 

[magoo2]

Sounds like a lot of small secondary wire to me.

 

[StevenSmart2]

To answer the questions, the problem is undersized secondary wiring with respect to voltage drop (Circuit breaker is adequately matched to the wire).

Basically whatever could be found was utilized to provide electrical between buildings. Initially this was not a big deal since the load was primarily lighting with a large diversification. As things have grown it's becoming more of a problem.

Thanks for the input.

 

[ykee]

If you've got lots of incandescent lights, maybe you could replace them with fluorescent, it might reduce the load a bit.....I know you said they have no money, but some local gov't & power corps have subsidies for this.

 

[StevenSmart2]

Fluorescent would be nice, but in Manitoba, Canada where it's -40C/F a lot we would need low temperature ballasts (the buildings are uninsulated and unheated).

I don't suspect there are any termination problems, purely voltage drop problems.

 

[CJCPE]

You should check for situations where excessive motor current caused by reduced voltage could trip branch circuit breakers and put out lights that are illuminating the use of power tools. That could be a safety issue.

 

[itsmoked]

That is such a large voltage drop!
120-80 = 40V

If you have this while drawing 10A you have:
40 x 10 = 400W of unintended losses. Is this not detrimental to their operating costs? Is not the eventual loss of all the motors a problem?

But to me the biggest question is where are these 400Ws showing up? If any of it is bottled up in a space somewhere you could have a fire. Ever grab a 7-1/2W night light bulb?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Yeah, but if it is because it is a long stretched out run, not that big of a deal I wouldn't think. A lot of overall watts loss spread out over a long wire is not much heat risk in any one spot, especially in Manitoba! They don't call it "The Great White North" for nothing...

Another remotely possible safety hazard may be anything that uses relays or contactors for on-off control, for instance your door controls and compressor. You are approaching the limits of "pull-in" voltage in most cases (typically 80% for relay coils), so it may be that something important may not turn on at the right time. Then if you have even a slight drop from the utility source, you are also approaching the typical 70% "drop-out" voltage of coils, meaning that something that is SUPPOSED to be running may turn off when you can't have that happen. Think of someone driving out of a roll-up door as it open, anticipating that it will finish the job, but the voltage drops and the controller stops it mid way. On the compressor, if it uses a contactor to turn it on and off, it may chatter and start a fire.

I would go talk to a big hardware chain store (do you have Home Despot up there?) or maybe an electrical wholesaler to see if they would be willing to donate some wire of proper size. Or enough smaller wire to make a new run and remove some of the loading from the existing circuits.

Then tell them to quit expanding without the funds to do it right. I know it seems harsh, but I work with several charities and sometimes I see the same thing. They get lots of volunteers who are willing to work, but there are no proper facilities for them so they want to start doing things like converting closets and garages. I suggest putting them to work on raising more funds right away while they are eager, THEN expand facilities in a safe and sane manner. Housing them in unsafe work areas is not going to do anyone any good if someone gets hurt.

 

[StevenSmart2]

Itsmoked, thanks for reminding me that the "400W" of losses is going somewhere. The runs are burried so it's going straight into heating the ground.

Jraef, your point about door controls not working correctly is a valid one. There is such high diversification on the site that it's only when the next building over also had their door running that the voltage really sags down to the 80V level.

Last night we discovered other issues on the site such as using service conductors, which don't have a bonding wire, for some of their long runs (USEI). I believe they we will now start moving forward with replacing the underground wiring and doing it right.

It's going to be a shock to their culture changing from "doing everything under the wire" (no pun intended) to "doing everything above board".

Thanks for the suggestions.

 

[RRaghunath]

If you have any motors related to fire safety such as fire water pump drives etc.
you need to look at the torque availability withat reduced voltage to start and accelerate the motor in case of eventuality.
Similarly, operation of fire dampers (in Air conditioning ducts etc.)also can be an issue.

 

[7anoter4]

hi StevenSmart2
First of all I think that you have to check your measurements, as fluorescent lamp does not work at all at such a voltage drop.
If it is really so, the local utility is in a serious trouble .For 10 A required by your facility, such a drop is scandalous and no customer could tolerate this.
There are some measures to reduce the consume:
Compact fluorescent will save 60-70% energy per same luminous flux [lighting effect].
If you can substitute the tools for others at 110 V rated [or less] it would be some improvement.
You may reduce a little also the total current by compensated cosfi with capacitors.
Best Regards