Watt-Meters??

We have a potential client (large industrial) who is considering moving to LED technology. They do however, want to explore actual delta in kwh and watts to get some kind of confirmation on our estimated savings. Is there a a device we can temporarily install to measure a circuit for a week and then change out the fixtures on that circuit and then re-measure? I've seen watt-meters for residential applications but nothing for commercial.

Any help is appreciated.
 

GoldDigger

Moderator
Staff member
We have a potential client (large industrial) who is considering moving to LED technology. They do however, want to explore actual delta in kwh and watts to get some kind of confirmation on our estimated savings. Is there a a device we can temporarily install to measure a circuit for a week and then change out the fixtures on that circuit and then re-measure? I've seen watt-meters for residential applications but nothing for commercial.

Any help is appreciated.
The first thing you need to ask is whether you really want a watt meter, which could be used at any time to measure the current lighting load on the circuit(s) or a watt-hour meter that you would leave in place for, say, 7 days to find the average usage over both working and non-working days.
IMHO the watt-hour meter will give you a more useful number. Especially if it also offers the instantaneous watt reading.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
You have to make sure time is left out of the equation. Either assure simultaneous operation or on 24/7.
 
The first thing you need to ask is whether you really want a watt meter, which could be used at any time to measure the current lighting load on the circuit(s) or a watt-hour meter that you would leave in place for, say, 7 days to find the average usage over both working and non-working days.
IMHO the watt-hour meter will give you a more useful number. Especially if it also offers the instantaneous watt reading.
so sounds like a watt hour meeting would be best. Any mfg recommendations?
 

MrJLH

Senior Member
Location
CO
so sounds like a watt hour meeting would be best. Any mfg recommendations?
I have used these in the past to perform load analysis on electrical panels in the past. These are tricky to setup the first time, but once you get the hang of it after a few times, you can do it with no problem. Just make sure the panel is de-energized. If you want a true loading on the panel you will need to folow NEC guidelines.

http://www.dranetz.com/power-quality-analyzers/

I used the PX-5
 

kwired

Electron manager
Location
NE Nebraska
What i mean is, if you're comparing the cost of operation of different load types, you have to make sure the hours of operation are identical.
so sounds like a watt hour meeting would be best. Any mfg recommendations?
But consider what Larry mentioned. If one load runs for 10 hours, make sure an replacement load is compared for same 10 hours. Otherwise an instantaneous watt reading of each load (presuming a steady load) should tell you one is XX% different than the other regardless of how many hours it may have ran.

Rather inexpensive "kill-o-watt" meter can tell you instantaneous watts, VA, power factor, etc. May not be extremely accurate, but should be accurate enough to be convincing that a certain item is pretty efficient compared to another item.
 

gar

Senior Member
190515-1507 EDT

thewiseguy31:

I agree with kwired that a Kill-A-Watt EZ (about $30 at Home Depot), and additionally a light meter might be all you need.

The Kill-A-Watt is limited to nominal 120 V and 15 A. These are relatively accurate and have 0.1 V resolution at 120 V. To demonstrate what you want only requires a wattmeter. You don't need to measure watt-hours.

You probably only need to demonstrate the difference between two single fixtures. This may be in the capability of the Kill-A-Watt EZ.

The experiment needs to be structured so the number of fixtures for each type of source covers the same surface area, and at the same light level. One fixture of each type might be sufficient. Then you simply show the differences in power input, and power factor. An LED vs fluorescent might show 50% less power input, and PF of LED might approach 1.

As an aside you should evaluate the RFI (radio frequency interference) of your LED.

.
 

drktmplr12

Senior Member
Location
South Florida
190515-1507 EDT
The experiment needs to be structured so the number of fixtures for each type of source covers the same surface area, and at the same light level. One fixture of each type might be sufficient.
.
to expand on this, a one-for-one replacement with LED technology may not always be practical. pay very close attention to the light temperature and lumen output of the replacement fixture to be sure you are comparing apples to apples.
 
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