Measuring total house current

Reply

  #1  
Old 07-17-14, 01:26 PM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 1
Measuring total house current

To determine what size generator I need, I want to know how to determine the total current draw when I have both 110 and 220 devices running. I have an AC/DC Fluke clamp adapter but I'm not sure if I measure each hot leg of the 220 entrance and add them to get the total draw?
 
Sponsored Links
  #2  
Old 07-17-14, 01:55 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,484
Welcome to the forums.

You could measure both legs of the service to compute current draw but usually you add up the wattages of the connected loads. During a power failure you need to conserve power and not everything needs to run.
 
  #3  
Old 07-17-14, 02:10 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 20,859
I agree...you'd have to turn on every appliance, A/C, fan, lamps, etc, to get an accurate representation. That can be hard to do when some loads are intermittent (fridge, A/C, etc).

Better to just read the nameplate data on essential items such as fridge, freezer, A/C or heat, lights, computers, TV, and such. Adjustments can always be made when Mama/Daughter absolutely needs her blow dryer when the power is out.

Most people could easily live almost normal life with an 8KW steady load standby genset. If you want every modern amenity with no lifestyle impact, then it could shoot up to 20KW pretty easily.

If you really want a whole house standby gennie...then it will probably need Pro install and they will do any load calcs needed.
 
  #4  
Old 07-17-14, 02:51 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
Unless you have money to burn sizing a generator to supply the entire load of your house is extreme overkill. A kitchen range all by itself could use between 8 and 12 kilowatts, a water heater is generally 4.8 kilowatts. Air conditioning could be a minimum of 6 kilowatts and the A/C would also have a starting load that could be three times the running load.

A 200 ampere (at 240 volts) service is 48 kilowatts. A 100 ampere service is 24 kilowatts.

I have a 200 ampere service but I have a 2.8 kilowatt generator (3 kilowatts surge for 20 minutes) and I have no problem living with this when the power goes out. It handles my furnace, refrigerator, microwave oven (or table top convection oven or hot plate) along with my TV and video equipment pr Internet connection and a few lights. The smaller the generator the less it costs to purchase and the less it costs to operate.
 
  #5  
Old 07-17-14, 05:24 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,484
WHAT ?!!?!?!? No blow dryer Furd

I consider myself lucky in that all my appliances are natural gas. I use a 5K Honda and run the entire house. Washer and dryer same time. Microwave no problem. No central air.... just ceiling fans. I used about 5-6 gallons of gasoline a day.

So what your appliances run on is important in your calculations.
 
  #6  
Old 07-17-14, 05:27 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,359
There are demand load calculations for generators available online.
 
  #7  
Old 07-17-14, 09:44 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,374
WHAT ?!!?!?!? No blow dryer Furd
Nope, no women have lived here for quite some time. I think it has been eight years or more since one even spent the night.
 
  #8  
Old 07-18-14, 04:15 AM
bigboypete's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2013
Posts: 218
Nope, no women have lived here for quite some time. I think it has been eight years or more since one even spent the night.
Too much information Bro... what you do with your amp probe in your spare time is your own business.

To the OP, google generator load calculator and you should be able to find a handy tool to calculate your load. However, if this is a whole house standbye generator, don't sweat it, the electrician you hire for the install will do the appropriate load calculation to assure you have an efficient sysystem installed... all you have to worry about is signing the check.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'