Warranty inspections

[Barry Adair]

Builder won't admit there is a problem with this house.

This was just one of many throughout this house.

[David P. Valley]

Hmmm, I would have been curious and accessed this outlet.

[Mike Whitt]

Originally Posted by badair

Builder won't admit there is a problem with this house.

This was just one of many throughout this house.

Why do you think there is a problem?

Could you explain what is happening a little more?

[Barry Adair]

Too long a cable run is what has been determined on these McMansions, in the past.
We'll see on this one.

[Barry Adair]

Originally Posted by Mike Whitt

Why do you think there is a problem?

Could you explain what is happening a little more?

Both vl and vd are deficient

Further info:
http://www.idealindustries.com/media...64_165_ins.pdf

[Robert J. OConnor]

Originally Posted by badair

Too long a cable run is what has been determined on these McMansions, in the past. We'll see on this one.

Possibly longer cable runs combined with use of the back stab push-in connectors on receptacles (which doesn't typically give as solid a connection as using the terminal screws ... but quicker to install).

[Marc D. Shunk]

Did the owners have something in their contract with the builder with respect to voltage drop? Lacking that, there's certainly nothing else that would bind the builder to "fix" anything.

[wsiegel]

Mark,

Is it true that they are addressing voltage drop in the 2008 NEC??

[William J. Decker]

I see this all the time, in McMansions, and have been told by builders and even code inspectors that it is not a problem. I have never seen it fixed.

I have, in these same houses, had reports from the buyer (during the warranty inspection) that the big screen digital TV or the computer in the room died or had to be replaced, multiple times, on two cases.

Digital deviced do not like voltage drops.

I have seen some (pretty common, around here) as high at 25% at 12 amp load.

It may be "code" (i.e., within local code), but it sure ain't right.

[Michael Larson]

Originally Posted by wdecker

......Digital deviced do not like voltage drops......

Since many digital devices are powered by switched mode power supplies that often have input ratings of 90-264 Vac., I find your statement surprising. Do you have a source of information on this?

Not to bust your chops Will, but I used to test this type of power supply as an engineer to verify it was capable of outputing the corect DC voltage under the range of voltage input ratings on the label. The standard for this type of power supply is UL 60950.

Output voltage — Linear power supplies regulate the output by using a higher voltage in the initial stages and then expending some of it as heat to produce a lower, regulated voltage. This voltage drop is necessary and cannot be eliminated by improving the design, even in theory. SMPSs can produce output voltages which are lower than the input voltage, higher than the input voltage and even negative to the input voltage, making them versatile and better suited for widely variable input voltages.

[cgoyette]

Items with a transformer like all the new printers these days hate low voltage. The transformer gets real hot. The drop that is shown in the picture has the voltage down to 96 VAC that seems excessive to me and it was a WARRANTY inspection. I think the 5% rule is a bit overrated but way beyond that on this one.

Curt

[Marc D. Shunk]

Originally Posted by cgoyette

Items with a transformer like all the new printers these days hate low voltage. The transformer gets real hot. The drop that is shown in the picture has the voltage down to 96 VAC that seems excessive to me ...

Yes, but consider that the voltage drop is entirely dependant on the connected load. Your printer example isn't that big of a load. Given the load diversity in a dwelling, voltage drop is rarely a legitimate concern.

[cgoyette]

Originally Posted by Marc D. Shunk

Yes, but consider that the voltage drop is entirely dependant on the connected load. Your printer example isn't that big of a load. Given the load diversity in a dwelling, voltage drop is rarely a legitimate concern.

Its not the load it, they seem to hate low voltage. The transformer itself gets real hot when the voltage is low. I read something in the instructions I'll try and find it and scan it.

Curt

Let me clarify the extenstion cord has a black box thats the transformer on the new printers and some copiers.

[Marc D. Shunk]

Originally Posted by cgoyette

Its not the load it, they seem to hate low voltage. The transformer itself gets real hot when the voltage is low.

You seem to not understand how voltage drop works, so I'll try to break it down for you.

You will have little to no voltage drop at low loads. The SureTest puts a 15 amp load on the circuit to measure that drop. At half that load, the voltage drop would be much, much less. At the load that a printer, for instance, puts on that circuit, the voltage drop wouldn't be anything to even talk about. The amount of voltage drop is directly proportional to the connected load.

Here's a little chart that shows how much #12 you can run various distances for various loads if you're interested in maintaining 3% vd.:


There is absolutely no way to know how a receptacle will be used in a home, so the application of a 15 amp load to calculate voltage drop is dubious at best.

[Mike Whitt]

Originally Posted by Marc D. Shunk

There is absolutely no way to know how a receptacle will be used in a home, so the application of a 15 amp load to calculate voltage drop is dubious at best.

Marc,
It took me a while to get someone in my area to understand that in a dwelling unit a load of 3 watts per square foot was all that was required to be installed.

Their argument was the receptacle was rated at 15 amps so it should be loaded to 15 amps when doing a voltage drop test.
I then ask if they knew what the required was to be used for a receptacle for commercial and industrial installations where the possibility of a large load to be connected was much higher.
When he said no I point him toward 220.14(I) and told him this was the load used to size the conductors and overcurrent device for this same receptacle that he was loading to a full 15 amp load and pointing out a voltage drop.

Originally Posted by NEC

220.14(I) Receptacle Outlets. Except as covered in 220.14(J) and (K), receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or for each multiple receptacle on one yoke. A single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles shall be calculated at not less than 90 volt-amperes per receptacle. This provision shall not be applicable to the receptacle outlets specified in 210.11(C)(1) and (C)(2).

Using this thinking a one and a half amp load at 120 volts would still have 110 volts on a 1000 foot run of #14.

If voltage drop was a life safety issue it would be mandated by the building codes but it is nothing more than a design issue therefore not regulated by the building codes.