Arc welder question

Would it be easier to hire a 3 phase generator or a single phase welder for the job?

Mike

Unfortunately - not in this case - the connection is accross any two phases to get 415v single Phase I doubt if you could do much welding as the open circuit voltage will only be 240/415 of what it should be - 57% approx, making striking and sustaining an arc unlikely. If the max input short circuit current is rated at 109A, I would suspect that the current draw is a bit too high for a domestic suplyanyway as the power factor of this welder is likely to be very poor.

Dave

Check for connections to use it on 240v. Most of this type of welder usually are made that way. (Should be shown on connection cover or connection plate on welder)

I have owned a few welders that have a setup inside where you can change a couple of connections inside to swap from 415 to 240v.

It would be worth having a look inside the case. This is quite common.

Grames

Thanks for your replies everyone, much appreciated. This welder is a straight 415 volt unit, no taps. Normally I'd just do it properly and get 3 phase power connected but this is only for a smallish job. Theres actually 3 phase on the site, but its split up into single phase supplies to each individual unit. So theres no non-dodgy way of getting 415 volts :) Just be getting a genset and usign the three phase mig instead I think.

Just while talking about power stuff, does the *average* american house really have a 200 amp supply? Thats really huge compared to houses here and aircon is really common too as is electric hot water. Normal houses in the suburbs here have an 80 amp service fuse. We have a 3 phase supply to our house here as do a lot of houses in the immediate area, mainly for 3 phase bore pumps (semi rural area).

anyway, tahnks again

James

New stand alone homes and service upgrades (where an only fuse box is replaced) typically have a 200 amp panel.

The actual draw is almost always less than 100 amps. (We have had "emergency" service provided by a auto-transformer with a 100 breaker. We lived more or less as we always do and the breaker didn't trip.)

The BIG power consumers are the HVAC system (in cold weather, most new homes around here (Northern Neck of Virginia) use 100% resistance heating. The heat pump may be running but just can't put out much.) In a worse case with a heat pump in defrost and all the resistance heaters switched in, the HVAC system COULD draw about 100 amps by itself. Throw in the water heater (20 amps), water pump (10 amps), stove (40 amps), and some of the small stuff that draws about 10 amps (hair dryers, irons, whatever) and you can get close to 200 amps.

Well, if you have 3 phases, your 80 amps is equivalent to our 120 amps. (3 x 80 = 2 X 120).

I'm probably missing something, but isn't American power 110 volts, so to get as many watts power, they'd need twice the amps as our 240v system?

On a similar note, while I've been to the US a few times, I've never taken the time to look - do they have a MEN (Multiple Earth Neutral) system? Do they require RCD (Residual Current Device) breakers on new houses?

Inquiring minds and all that.

Russ.

What's the external temps where you still get useful heat pumping ?

I currently use 100% resistance heating and was considering a heat pump. I have gas as an available alternative.

Yes, and it would be single phase. 240/120 from a center tapped xfmr with the center (neutral) solidly grounded. (National electric code requires it) Household appliances commonly operate at 120volts. (exception: electric clothes dryer, electric cookstove) Typically a home is supplied by a 15Kw, pole mounted transformer.

I believe that 3 phase to a single family residence is a no-no, though three phase to an apartment building is quite common.

Three phase would be a vast improvement, but the experience level of electrical installers varies WIDELY here in the US and there are many "electricians" here who would not know how to install it and have it work properly.

I live in Kentucky and there are some superb electricians here....there are also some well-meaning individuals whose eyes roll back in their heads when you start talking about wiring a 3-way light switch.

As for aluminum wiring, the price difference with copper is so small anymore that we dont see much of it. Here in KY is it illegal in small sizes (branch wiring), though I believe that you could still use it in larger sizes for feeder circuits and it is very common on incoming service conductors. The power companies all use aluminum for their conductors unless they are very close to the ocean.

Feelings against aluminum runs high in Ky due to the fact that it was found to be a major contributor to a "supper club" fire several years ago that killed over 100 people.

AFAIK, the panel rating is at 240VAC. All the heavy loads (eg. aircon, water heater, clothes dryer, range, oven, heat pump, spa heater, etc.) in American and Canadian residences are wired across the 240V lines.

Best regards, Spehro Pefhany

Thanks - that pretty much covers it - it all seems identical to Oz (although I am thoroughly unqualified to comment), except for the dual feed trick. As others have said, the only variation here tends to be the option of three phase, but isn't very common in domestic situations, unless there's a specific requirement (like a 3-phase beer fridge for serious drinkers).

Russ.