DYI'er Trying to Confirm kWh

[SKalkbrenner]

Hello everyone. After searching online for help, I finally gave up and decided to register here.

Background: I recently finished renovating a commercial property into living space for our family. The old service had a 100A standard service as well as a 100A 3 phase supply.

I added 2 new sub panels (1 for both). Regarding the 3 phase supply, I am using 2 of 3 legs to supply my 240 appliances.

One reason for this move was because we have a ton more space. I totally expected a higher utility bill. But not at the level I'm seeing for sure.

I have tested a few appliances with my clamp meter, but my main question involves measuring at the panels.

Can I use my clamp meter on all incoming service feeds to determine amperage - then calculate kWh from those? My question is how does the calculation change on the individual 3 phase lines?

I'm not sure if I do the standard V x I across the board? Hopefully I have explained things properly. Please let me know if you need more details in order to offer insight.

Thanks,
Steve

 

[plugsandsparks]

Depends what you are trying to understand. First thing is to check the bill against your meter readings. With all meters it is possible to calculate KWh by noting the readings and measuring over time with a stop watch. You can use a clamp meter for instantaneous current readings but these readings will include "reactive" power as well as "real" power if you simply multiply the current by 240V - so will read higher than actuakl KWh.
In terms of 3 phase, if you only have single phase loads, then just measure the current at each live terminal leaving the supplying breaker, rather than the tails as this will at least tell you where the power is going.
In terms of what appliance is using the power. Lighting , this time of year can be a good load. Any electrical heating of space or water. Things like kettles and cooking usually carries over from normal life, however induction hobs do use much more than gas.

 

[SKalkbrenner]

Thank you so much for your quick response.

My meter actually displays kWh so I am just trying to verify those numbers.

My ignorance may shine through with my upcoming comments, but here goes ...

If I wanted to check my dryer- at the breaker - I would use my clamp meter on 1 of the 2 hot lines from the 2 pole breaker, then multiply by 240, correct?

But, if I back things up to each service line (not the 3 phase), both come in at 120V. So could I make 2 separate calculations on the 2 lines to get overall usage for the standard supply?

Thanks again.

 

[plugsandsparks]

eeeekkk, did not spot USA , forget my advice about clamping and X by 240, can only advise to use the meter and a stop watch. Sorry all this international stuff can catch us oldies out, lol

 

[telectrix]

eeeekkk, did not spot USA , forget my advice about clamping and X by 240, can only advise to use the meter and a stop watch. Sorry all this international stuff can catch us oldies out, lol

write out 100 times... " I must check the flag on the poster's avatar". and don't sellotape 4 pens together like we used to do at school.

 

[plugsandsparks]

Flag ? doh

 

[Megawatt]

Hello everyone. After searching online for help, I finally gave up and decided to register here.

Background: I recently finished renovating a commercial property into living space for our family. The old service had a 100A standard service as well as a 100A 3 phase supply.

I added 2 new sub panels (1 for both). Regarding the 3 phase supply, I am using 2 of 3 legs to supply my 240 appliances.

One reason for this move was because we have a ton more space. I totally expected a higher utility bill. But not at the level I'm seeing for sure.

I have tested a few appliances with my clamp meter, but my main question involves measuring at the panels.

Can I use my clamp meter on all incoming service feeds to determine amperage - then calculate kWh from those? My question is how does the calculation change on the individual 3 phase lines?

I'm not sure if I do the standard V x I across the board? Hopefully I have explained things properly. Please let me know if you need more details in order to offer insight.

Thanks,
Steve

Steve that is a tough question but I’m assuming that you know KWH means and especially on 3 phase panels. They make CT’s that you could install on your panels or get or borrow an amperage recorder and check it every 24 hours to give you a more accurate reading on how much power you are actually using. Other than that I don’t know what to tell you. These guys on this forum are pretty sharp and should be online shortly. Good luck