Welding Tips and Tricks

Yes - watts is giving you the total amount of power carried which equates to necessary cable size due to heat created by the slight resistance of the cable hence ally cable carries less than copper - but there is no 1 answer on cable size without knowing distance & accepted voltage drop so it's slightly more complicated than saying so many amps equals 1 size cable - also regs vary from country to country - I will post back when we have an answer from the power company & the exact distance this supply will cover but for the time being I will just say this is in the UK & our power is nothing like yours - I appreciate all responses but to be honest most active members here are in the USA & while most aspects of welding are pretty much the same anywhere the power supply in you country is fairly unique & not applicable most anywhere else - but thanks again to all that pitched in.

Any updates on what happened here?

It so happens that I've got a 4 wire Delta three phase at work which is an older industrial standard seldom-used now. I've got a guy I hired to hook up power to a new grinder I've got and it's turning into a more complicated scenario than I had anticipated. I figured I was just going to have 2 boost (edit, boost not buck) Transformers on the main legs but it would appear there's more to it than that. I need 460 volts at 22 amps. Mine has a Hot Leg as the third phase so that's kind of throwing a wrench in the works.

Here's a decent link describing various power set ups.

https://ctlsys.com/support/electrical_s ... _voltages/

@BugHunter

Sorry on delayed replies - I'm not often anyplace with internet of late - there is no news yet from the power company - I believe they have made a date middle of next week to come out but it's unclear what this is for - it's never simple with them ! thanks for the power diagrams - I did not realize how many variations you guys have - it seems an over complicated system & very restrictive for a nation that uses so much power to be lumbered with that 120volt household power - the closest you have to us is the 4wire 3phase wye type shown except ours is 240volt from any of the 3 lines to neutral - sometimes earth can be bonded to neutral but not always & any line to to line is 415 though used to be 440 - ( RMS ) will let you know when I have any further news.

noddybrian wrote:@BugHunter

Sorry on delayed replies - I'm not often anyplace with internet of late - there is no news yet from the power company - I believe they have made a date middle of next week to come out but it's unclear what this is for - it's never simple with them ! thanks for the power diagrams - I did not realize how many variations you guys have - it seems an over complicated system & very restrictive for a nation that uses so much power to be lumbered with that 120volt household power - the closest you have to us is the 4wire 3phase wye type shown except ours is 240volt from any of the 3 lines to neutral - sometimes earth can be bonded to neutral but not always & any line to to line is 415 though used to be 440 - ( RMS ) will let you know when I have any further news.

The number of different systems here might have to do with the geography, the US is a LOT more spread out than the countries in Europe, and within it there's 50 states all of whom have regulatory jurisdiction over power companies, in addition to federal oversight. Then too, I have a favorite saying, "That's the great thing about standards... Everyone has their own!"

To make matters worse, different machine manufacturers build machines using motors and controls that require different input power. Just like I'm dealing with now, I've got a change in voltage I need to do and there's loads of different scenarios when I try to buy a transformer. Even calling electricians and electrical supply companies, they're lost when it comes to this stuff. Doesn't give me a great feeling dealing with em.

BugHunter wrote:Wire size is based on Watts, not amps. A wire will carry a certain amount of power. That is it. 100 volts at 2 amps is the same power as 50 volts at 4 amps.

I get what you're trying to say about watts, but while your scenario is equal wattage, the 100V/2A will heat up the wire ½ as much as the 50V/4A scenario. That is why conductors have an amperage rating on them in the first place; usually because of the thermal rating of the insulation.

Oscar wrote:

BugHunter wrote:Wire size is based on Watts, not amps. A wire will carry a certain amount of power. That is it. 100 volts at 2 amps is the same power as 50 volts at 4 amps.

I get what you're trying to say about watts, but while your scenario is equal wattage, the 100V/2A will heat up the wire ½ as much as the 50V/4A scenario. That is why conductors have an amperage rating on them in the first place; usually because of the thermal rating of the insulation.

It's actually worse than that.The losses increase with the square of the current, so if you double the current, the losses quadruple. So in this example, 100V/2A will heat the wire 1/4 as much as at 50V/4A.

That is why all of the high power transmission lines are at very high voltages, it keeps the losses due to the resistance of the lines manageable.

Update - last week 2guys in 2 vans arrived & dug the 3 feet from our duct to the power pole ( we were not allowed within 3feet of they're pole but could easily have dug it ! ) they put in a duct to the pole & filled in the little 10" wide trench - 2 days later another van & a cherry picker arrived & put a cable down the pole but can't connect it because it's now up to whoever you chose to buy your power from to install the meter so now we wait for them before proceeding ! - today a 32ton tipper lorry arrived loaded with soil to fill in the trench the first guys had already done ! - will update you when anything else happens - I wish I was making this up but I feel like I've gone back to the 70's on a union job !

I know what you mean...


For 2 years I tried to get the state to come fix the drain in the street outside my shop. I had called the city and they said it's a state road, not their issue. It was falling in due to being so neglected. The state does the maintenance on the road as well as plows the snow, not the town... The guy who mows my grass actually works for the state ON A ROAD CREW, even fixing this very street, and had gone to his boss multiple times asking for it to be fixed, to no avail. I finally stopped asking them to come fix it and gave up.

On day while sitting here, the city guys are parked out here walking around, across the street, down the street, I'm like ??? huh?? Pretty soon they come in and ask me, why didn't you call us about this drain, it's really bad... Uhh, I did and you said it's the state's issue. Oh no, no, if it drains down the street it's the state's responsibility, but if it drains across the street, that's ours.

??????

Good luck on the power hookup.

@ BugHunter.
sounds like things work about the same both sides of the pond where officialdom is involved ! - on the cable front I found an off cut end the linesman must have snipped off while up the pole & it measures 35mm which I think is in the middle between your 2 & 1 AWG - I had previously told our electrician based on our distance to install & voltage drop goals I thought we would need to go 50mm which I think is just a tad under your 0 AWG - being that the incoming supply is already about 2/3 of a mile from the transformer dropped down from 11kv overhead there seems little point using thicker than 35mm for the last 400 ( ish ) feet & their cable is of the ABC type which is aluminum ours will obviously be copper - maybe we just been over thinking it - as & when we get power on I'll update the thread & thanks to everyone that contributed.

BugHunter wrote:[Wire size is based on Watts, not amps. A wire will carry a certain amount of power. That is it. 100 volts at 2 amps is the same power as 50 volts at 4 amps.

Actually Oscar dispelled this recently, but it must have been in another thread. It has to do with the heat, and the heat is not the same for 100 volts at 2 amps as it is at 50 volts at 4 amps.

In addition it was suggested that this is the reason that power companies run high voltage on the power lines, to keep the heat down and that makes sense.

I am not an electrical engineer, but it made sense when I read it. So no, 100 volts at 2 amps is not the same as 50 volts at 4 amps as I now understand it and that is why Oscar was saying that wire size is determined by amps.

clavius wrote:

Oscar wrote:

BugHunter wrote:Wire size is based on Watts, not amps. A wire will carry a certain amount of power. That is it. 100 volts at 2 amps is the same power as 50 volts at 4 amps.

I get what you're trying to say about watts, but while your scenario is equal wattage, the 100V/2A will heat up the wire ½ as much as the 50V/4A scenario. That is why conductors have an amperage rating on them in the first place; usually because of the thermal rating of the insulation.

It's actually worse than that.The losses increase with the square of the current, so if you double the current, the losses quadruple. So in this example, 100V/2A will heat the wire 1/4 as much as at 50V/4A.

That is why all of the high power transmission lines are at very high voltages, it keeps the losses due to the resistance of the lines manageable.

Absolutely correct, I had a major brain fart there! P=I²R ! No idea how I missed it. This is utterly embarrassing!

TraditionalToolworks wrote:wire size is determined by amps.

and insulation properties, and typically other factors that electricians have a keen eye for. If simclardy was more regular on here, he'd jump in right now.

Oscar wrote:Absolutely correct, I had a major brain fart there! P=I²R ! No idea how I missed it. This is utterly embarrassing!

No worries Oscar, you proven to be twice as right!

Oscar wrote:

TraditionalToolworks wrote:wire size is determined by amps.

and insulation properties, and typically other factors that electricians have a keen eye for. If simclardy was more regular on here, he'd jump in right now.

Would be good to hear what he has to say if he sees this. I agree, too bad it's not more regular on this forum. He's a wealth of electrical knowledge. Most of the charts I've seen are in amps for wire size.

Did you know there’s less resistance when there’s more strands of copper in a given size?

Poland308 wrote:Did you know there’s less resistance when there’s more strands of copper in a given size?

Do tell.

(Unless it has to do with the old-wives tale of skin-effect which plays no part in 60Hz systems. I've actually calculated it, the skin-depth, previously )

Just had to throw it out there.

But I meant less resistance when you drag it across the floor and around your bench legs.

All jokes aside I was of the understanding that a solid single conductor per given size was the best - stranding only coming into play with regards to flexibility in use / less likely to fatigue crack when exposed to vibration & the effect briefly mentioned previously if used on high frequencies.

Yep high freq is better on multi strands. Solid is only better because it hold up to heat better. And it makes connections that are less prone to issues.