View Full Version : Blowing Breakers
I read a lot of post on these and other boards where guys are talking about electrical breakers and such.
I heard guys setting up 40 amp and up breakers on there power boards to run single phase welders off of.
Here in Australia as far as single phase goes you have generally only 10 amp and 15 amp outlets - 240 volts 50Hz.
For 3 phase we have 10 amp and up - 440 50 Hz.
I've got a single phase TA 185 that I purchased from the US. When it arrived I just loped of the whooping great plug on the end and installed an Aussie 15 amp one - just as I'd seen done on the CIGweld badged ones they retail here. I took the liberty of installing the industrial style one as opposed to the whimpy one they use.
The TA 185 runs on a 15 amp loop in my factory and I've never blown a fuse once - even welding Aluminum.
On the same circuit I've used machines of up to 300 amps without a hitch.
Can someone explain what I'm missing here? Why do you guys in the US blow breakers all the time?
03-07-2004, 03:07 AM
As simply as I can explain it, your voltages are double what ours are, so your amperage draw is roughly half of what we normally experience. Another factor that comes into play is voltage drop from line loss.
Additionally, most of the people who are blowing breakers are probably using a fully magnetic breaker, witch by it's design cannot sustain high inrush currents.
In the US, our power system is normally 120/240 volt single phase, with an allowable variation of 10% on the voltage. We only have 3 phase available in industrial sitings, where the voltage will normally be 208, 240 or 480 phase to phase, 60hz.
The Canadians also have 575 volt 3 phase systems.
wasn't aware that these guys were using 110 volts?
The TA 185 is set up for a 208-230 input voltage.
When I lived in the US I noticed most homes had at least one 220 volt outlet in the laudry for washing machines etc. So I'm assuming to get this in a US home they are hooking up two lots of 110 volt, correct? That would explain it.
Wasn't aware that the actually delivery connection to the house was only 110 volt.
Another question if I may? I noticed that most appliances in the US have pretty whimpy plugs on them and don't have an earth. Why? I't funny the sparky who helped me with the 3 phase installation of my factory told me a funny strory of when he visited the US. In his hotel he phoned up the reception to report that someone had changed the plug an cord on the hair dryer in the bathroom! He just couldn't believe that they'd use such a dicky cord and no earth.
Seems ammusing too in the context of some of the other hard *** points of your electrical code.
03-07-2004, 04:22 AM
We have a split phase system. 220 or actually 240 comes into the house via 3 wires. The main breaker panel alternates the 120 loads between neutral and one side of the 220. 220 loads connect to the 220 line. I have seen older breakers that trip before their rating.
03-07-2004, 11:37 AM
Most houses in the US have a 240 volt 100 amp service, with the supply transformer centertapped to earth, called ground here, providing 120 volts from phase to earth.
The wire that is called "neutral" is also grounded.
There are still older houses, that only have a 120 volt 30 amp service, dating back to the time when residential electrification was beginning, around 1930. From around 1950 to 1960, most residential services were 240 volt 60 amp.
About the only 240 volt loads in a US home will be a laundry drier or an electric stove or oven, unless the house uses electric heat.
The majority of circuits, 120 volt, are 15 amp, with 2 20 amp circuits in the kitchen.
Cordage to devices has always been a matter of manufacturers using the minimum they can.
Most 120 volt cords and plugs are 2 wire, without the earth conductor, and the plugs are polarized, so the neutral is maintained in correct reference all the way to the appliance, at least over tha last 15 years.
Prior to 1964 our codes didn't even require the earth wire to be connected at the wall receptacle.
We have also fallen in love with a device called the Ground Fault Circuit Interruptor, witch theoreticly deenergiges the 120 volt circuit if a fault current of .005 amps occurrs between either the hot or neutral wire to earth.
03-07-2004, 02:22 PM
And those devices which use only 2 wire are double insulated or plastic cased. Also the dinky cords are short and used on devices that are generally intermitant. Many do have "earth",, which really isnt earth, its a ground fault return path back to the neutral bar,, or to the transformer really.
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