Thread: 15amp welders on 10amp circuits

A fan heater can draw 2400watts. An oil column heater can draw 1800 to 2400 watts. A hair dryer can draw 1500 watts. Any combination of these could easily be plugged into the same double GPO.

Yes and if the circuit breaker was 16A it would trip. That's the point. The circuits are not designed to provide a constant 10A at every socket. They are designed to handle the expected load, with a suitable overhead. It's not a matter of 10 + 10 = 20 as was expressed in the question. A typical circuit with say 5 double GPOs would need a 100A circuit breaker to protect it if that was the way things were done.

I don't see how you can cater for a worst case scenario without taking into account load aggregation. Do you just think of a number and double it? Whenever I want a point added, the first question my sparky asks me is "what are you going to plug into it?" You can't just add points without consideration of the existing load.

The suggestion being made was that every 10A outlet in a circuit could be loaded up to 10A. This is clearly not the case. Simple maths proves that. The 10A refers to the maximum rating of that outlet. It does not mean you can plug a 2400W heater into every socket on a circuit.

There are several factors that determine what you'll get away with. Some of them include how old the house is, how many other things are plugged in, what their duty cycle is. There are too many variables for someone to just make the blanket assertion that there is no increased risk as some of you seem to do.

Do you deny that house fires are frequently caused by electrical faults? What do you consider causes those faults to occur?

Your point about 15A plugs is speculation. Nuisance tripping is a symptom of a circuit running at close to it's designed capacity. If you are constantly tripping the circuit, then whatever you are running is peaking above the maximum current draw. My take on the 15A plug is to make sure ample overhead exists on the circuit so that it is operating well within it's design parameters.

Some people like to sail close to the wind, others prefer a margin for error. Hence the drawn out debate in these threads I suppose.

I reckon it's time for a laugh on this thread, Anyway, when I worked the then Telecom as a Tech, we were changing towns over to automatic from the old manual system and also fix whatever faults they reported. We got a fault in one time where it was reported by the Sub that he couldn't hear the phone ringin anymore, so out we went to see what the problem was. It was normal for the liney's to dig in a DL (direct line) instead of whatever the old stuff consisted of, anyway as we went up the drive we looked out for issues with the DL but couldn't see any. So once we got to the Sub we asked what the problem was and he said, Hey? I'm mostly deaf and now since you guys put in the new line I cant hear the phone any more! Oh we said and looked around to find all the new installation to be fine! He had a 6" bell outside that when it rang, all the neighborhood knew he had a call! (he was bell deaf) So we asked him, how did you hear the phone before? His answer floored us! Well whenever the phone rings the dog runs up and down on his long run barking and yelping, that is how I knew the bloody phone was ringin alright! We looked around and sure enough the old guy had set up the dog run on the old earth return phone line and since we had put the DL underground the dog wasn't getting the 110V of ring through the chain and himself to ground that caused him to be crying out in pain no doubt. Bloody hell! We installed a tone ringer that has a wide range so he was happy then cause he could hear the phone now and so was the dog!

And that's the truth...Oddjob1

Poor dog must've developed a nervous tick whenever he heard a phone ring after that! Classic

Nearly wet myself laughing.

Originally Posted by Oddjob1

I reckon it's time for a laugh on this thread, Anyway, when I worked the then Telecom as a Tech, we were changing towns over to automatic from the old manual system and also fix whatever faults they reported. We got a fault in one time where it was reported by the Sub that he couldn't hear the phone ringin anymore, so out we went to see what the problem was. It was normal for the liney's to dig in a DL (direct line) instead of whatever the old stuff consisted of, anyway as we went up the drive we looked out for issues with the DL but couldn't see any. So once we got to the Sub we asked what the problem was and he said, Hey? I'm mostly deaf and now since you guys put in the new line I cant hear the phone any more! Oh we said and looked around to find all the new installation to be fine! He had a 6" bell outside that when it rang, all the neighborhood knew he had a call! (he was bell deaf) So we asked him, how did you hear the phone before? His answer floored us! Well whenever the phone rings the dog runs up and down on his long run barking and yelping, that is how I knew the bloody phone was ringin alright! We looked around and sure enough the old guy had set up the dog run on the old earth return phone line and since we had put the DL underground the dog wasn't getting the 110V of ring through the chain and himself to ground that caused him to be crying out in pain no doubt. Bloody hell! We installed a tone ringer that has a wide range so he was happy then cause he could hear the phone now and so was the dog!

And that's the truth...Oddjob1

Originally Posted by silentC

No, but suggesting it is would be part of clutching at straws to justify your argument. It's certainly not illegal to operate a table saw without a power feed or a saw stop. Doing your own wiring is.

I'm pointing it out from a safety perspective. Everyone makes their own choices regardless of weather or not it is legal and that is not the issue here; we all know that we are not allowed to do it.

If un-saw-stopped saws were made illegal tomorrow, would you throw yours out, or keep using it?

Can you point to the section of the Electricity (Consumer Safety) Act (the relevant act in NSW) where it makes undoing the screws fastening a power point to the wall illegal?

In this discussion that you were part of here:
https://www.woodworkforums.com/f28/il...tml#post532620

Electrical Safety Act 1945. It's part of a fixed installation, therefore it can't be worked on by unqualified people. There does not seem to be any exemption for 'covering plates or attachments', and since undoing the screws exposes live connectors I would have to say that it most definitely is covered. At the very least you would need a connect/disconnect licence. (note that the similar legislation for plumbing does have exemptions letting people work on their own tap washers).

Interestingly, it seems that people are allowed to work on 240 volt systems that are supplied by wind or solar power and are not connected to the electricity grid. The NSW Fair Trading office did a review in 2003 and found no safety issues with non-grid connected DIY mains-voltage wiring.


Even if it was, it does not strengthen your argument one iota. Me being wrong about that does not make you right about suggesting a home owner put a 15A point on a 10A circuit.

Its not a 10 amp circuit. It is a 16 amp circuit as that is the minimum rating a power circuit can have (generally).

Your arguments are getting a little bit hard to follow but are you saying that the home owner should remove all of the existing 10A points on the circuit before fitting the 15A one? Or just that they should also unplug everything that's on that circuit?

We are talking about replacing a single GPO (with either one or two 10 amp socket outlets) on a 16 amp circuit with a single GPO (with a 15 amp socket outlet) as being the safer alternative to connecting a 15 amp appliance to the very same fixed wiring via a modified plug that would allow the appliance to potentially be connected via a 7.5 or 10 amp extension cord.

In the 'changed wall socket' scenario, there is a circuit breaker (correctly rated for the in-wall wiring), a socket-outlet (correctly rated for the plug) and an appliance lead (correctly rated for the load).

In the 'modified plug' scenario, you would be able to connect the (correctly rated) appliance lead (via a modified plug) to an undersized (7.5 or 10 amp) extension cord before plugging it into the very same (but not modified with a 15 amp socket outlet) GPO, leaving you with a section of cable that is not correctly protected by a circuit breaker and is under-rated for the load. It is therefore a less safe approach.

.

Originally Posted by murray44

Can someone point out where this hypothetical situation fails here.

I have a single 10A GPO (in the kitchen for instance) OK

I (or my sparky) replace the single GPO with a double GPO (I assume the cabling does not need to be changed) OK (no, it generally would not need to be changed unless old and crappy)

As a single GPO, the cabling would need to supply up to 10A
Yes, that would be the minimum, however AS3000 sets down minimum sizes for power circuits and they are (generally) 2.5mm which is rated to 16 amps when totally surrounded in thermal insulation.

As a double GPO, the cabling would need to supply up to 20A
Yes, if you plugged in two 2,400 watt loads the draw would be 20 amps, however the circuit breaker would be rated according to the thermal dissipation capacity of the cable. For 2.5mm cable, fully surrounded by pink batts, this figure is 16 amps; blowin' free in the breeze its 25 amps, and if it's underground, 32 amps. (table C5)

What's the big deal with running a 15A welder on the circuit?
It places a larger than expected load on the circuit which will lead to frequent nuisance tripping because it is likely that other appliances (TV, kettle, computer, microwave, aluminium smelter...) will pull the load over the (16 amp minimum) rating of the circuit. If, of course, these are not in use, then no tripping will occur as the only draw will be 15 amps from the welder. For this reason, the standard specifies that 15 amp sockets shall be on their own circuit.

Is a 15A GPO built any differently to a 10A outlet (aside from the obvious larger earth pin). No. See the thread I linked to a page or so ago. In fact, I'd be guessing that the design is actually rated for 20 amps so that 10, 15 and 20 amp GPOs share the same bits. If anyone has a copy of AS3100 (??), this might shed some light.

What is going to cause my house to burst into flames as some would sugest?

YOU HAVE DARED CHALLENGE THE INTERPRETATION OF THE HOLY BOOK!!! ONLY THE ANOINTED WHO HAVE SERVED THEIR FOUR YEAR APPRENTICESHIP SHALL HAVE KNOWLEDGE OF THE HOLY BOOK!!!!!! ALL OTHERS HAVE NO KNOWLEDGE OR REASON etc etc etc.

.(apologies if this dupe-posts)

Originally Posted by Master Splinter

Is a 15A GPO built any differently to a 10A outlet (aside from the obvious larger earth pin). No. See the thread I linked to a page or so ago.

Sorry but you are just guessing here. One example does not necessarily mean that is the same for all.

This is the sticking point for me - people make assumptions (very dangerous) that ALL 10amp gpo's are capable of running 15 amps for possibly sustained periods. The argument that a double gpo is running 20 amps is also a furphy, as apart from the connection terminals, all other parts are separate (ie switch and outlet).

The bottom line is that the standard says that 15amp equipment must be connected to a proper 15amp circuit. Rather than trying to get someone to do a substandard job, wouldn't it be better to show them how to do it properly? Crappy DIY electrical work (which is what you are suggesting he do) is just ammunition to those who wish to keep all electrical work out of the DIY realm.

Master Splinter, you can argue and try to pick holes in my words until the cows come home, it will not change the facts. This is a question that has a correct answer and that answer is:

1. The welder has a 15A plug to prevent the user from plugging it into a 10A GPO
2. The design of a 15A circuit is different to that of a 10A circuit
3. The design is specified in the Wiring Standard
4. The Wiring Standard is enforced by various acts of legislation

Your argument that a 10A socket can be replaced with a 15A socket because there is a minimum of a 16A circuit breaker completely ignores whatever else might be hanging off that circuit. It's the kind of flawed logic that does cause people to do silly things.

It also leaves a trap for future owners and it's the kind of thing that can wind up in court.

In short: irresponsible suggestion.

I strongly agree with SilentC. Standards are critical and should be observed and you should not interpret your own ideas as been safe. Don't ignore many years of R&D, improvements for the safe use of electricity and cabling. Everything has its limitations and therefore dont over load an outlet that was intended to deliver a certain power supply. If people want to run their own race thats fine but dont argue with them when good and correct advise is given. When you have a sparky do some work for you make sure you tell them what you intend to do so the the correct size wiring and other components are fitted to accommodate the intended use. They will do the right job with the purpose you have in mind and therefor dont understate the use to save a few dollars and then complain to them after you have melted it back and caused a fire.

This seems to be going on ad-nauseum, so in the spirit of only a few of us sick-os are still following it.

Master splinter
What's your take on 7.5 amp extension leads with 10 amp plugs sold in K Mart etc.?

silentC
You are pulling your punches, I said criminally irrisposable and that is what it is.

The poor zapped doggy.
There is a Telstra looping bolard near my place that has sent both my dogs reeling at different times when they have sniffed it.
Animals are more sensitive to electricity than us. I have heard of a horse electrocuted by the difference in potential (voltage) of where he put his front and back feet due to a near by earth fault.
May be he should have had safety boots instead of iron shoes.

I am sick of as well. No further comment from me on this thread.

Jeez you guys, this one has only gone on for 5 pages!!

The poor original poster has headed for the hills with his head in his hands long ago!

Crappy DIY electrical work (which is what you are suggesting he do) is just ammunition to those who wish to keep all electrical work out of the DIY realm.

Hey Vernon, I'm sure there's a contradiction in there somewhere. One thing's for sure, I wouldn't want to buy any house that blokes like Master Splinter have ever lived in

Originally Posted by silentC

Jeez you guys, this one has only gone on for 5 pages!!

I'm only on page 2.

Originally Posted by silentC

One thing's for sure, I wouldn't want to buy any house that blokes like Master Splinter have ever lived in

Amen to that.

You must have a different "posts per page" setting to me, Geoff. I can only handle it in small doses