Need help..Load computations

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  #1  
Old 05-10-06, 09:33 PM
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Need help..Load computations

hi guys, need help on how to compute the load capacity of a household circuit... in my case, i have 10 industrial sewing equipment... the markings on the motor says: 220v : 250w : 1.8-2.4amps, all those sewing machines are connected in a circuit with a 30amp circuit breaker... can you help me if the circuit breaker is capable of taking all the load... also connected within the circuit is 2 flat iron rated at 1000watts..
thanks in advance
 
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  #2  
Old 05-11-06, 09:26 AM
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There are no general purpose 30A household circuits in the U.S. or Canada; where are you located? Are all 10 machines in continuous use? Is the circuit wired entirely with 10 gauge wire and a 30A double-pole breaker? What are the plugs and receptacles on the circuit? Check this chart for reference:

http://www.leviton.com/sections/techsupp/nema.htm

In terms of load, you have 10 machines at 250W = 2500W. Also, add the two irons 2 * 1000W = 2000W for a total load on the circuit of 4500W.

The circuit capacity is 30A * 240V = 7200W. In terms of capacity, you are okay.

However, you may still have a problem here. You cannot attach the sewing machines to a 30A circuit unless the manufacturer of the machine has specified that a 30A circuit is safe. It will be listed as Max OCPD in the installation or owner's manual. The same goes for your irons. I suspect that you should break this into two or three 15A or 20A circuits.
 
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Old 05-11-06, 08:36 PM
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i live in the philippines, and yup all 10 machines are in continues use as well as the 2 1000w flat iron... as for the wiring, we used a #12 awg wire... is it too small? as for the breaker, yup it is double pole breaker... for the plug we use 2-30P...

hmmm based on what said i guess we have alot of changing to do, i already suspected that our current circuit is hazzardous, i was not consulted by my partners when they had the electrical wiring was done... they said not to worry because it was done by a "certified electrician".. i guess that electrical technician was just out to make a quick buck...

anyways thanks alot.. you've been a great help, and gave me a peace of mind, and know now what to do...

thanks again my friend..
 

Last edited by D-MAN; 05-18-06 at 06:02 AM.
  #4  
Old 05-12-06, 09:23 AM
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Since you're in the Philippines, most of what you learn on this forum is probably not useful. I really have no idea what your electrical system is like over there, but it may be very, very different than what we have in North America or possibly what is in Europe.

For example, your circuit would be allowed in the U.K., but would not be allowed in the U.S. or Canada; I can't say anything with regard to Asian standards as I simply don't know. If you follow the European standards locally, you may be just fine. The fact that the machines are 240V suggests that you might follow European standards. Typical voltage in North America is 120V. However, things like that get fuzzy when dealing with industrial grade equipment.

If running this in the States, I probably would have run a 20A circuit using #12 wire for the sewing machines, and a second 15A or 20A circuit for the irons using #12 wire. I don't think what you have is hazardous; it may be somewhat overloaded for #12 wire, but the North American standard is very strict with the 20A limit for #12. The actual rated ampacity of #12 is 30A, we just have a rule that forbids more than 20A on #12 as a safety margin.
 
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Old 05-18-06, 06:12 AM
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Actually, I learned alot from this forum... the standards we follow here are somewhat similar to north american standards rather than european... the only difference is the voltage which is 240v, we also follow NTSC standard for our television.. similar to U.S. even our driving configuration (left hand drive) is similar to u.s.
 
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