Thread: 15amp welders on 10amp circuits

Originally Posted by Geoff Dean

You mean, after reading this whole thread, you can make heads or tails out of it?

No, he's getting the Sparky in to translate it for him!

Originally Posted by JillB

I think it it time for the Moderator to close this thread. It has become circular and getting nowhere. The message has been made loud and clear by several contributors - don't use 10A GPO's or 10A circuits for 15A appliances, the consequences can be horrendous

Perhaps, instead of pleading for the discussion to be terminated, you could explain exactly what the "horrendous" consequences are, and also explain, fully, how they come about?

For example, perhaps compare and contrast the risks between plugging two 2400 watt heaters into a double 10A GPO as against plugging a welder with a 15A plug into the same socket?

Originally Posted by RustyArc

For example, perhaps compare and contrast the risks between plugging two 2400 watt heaters into a double 10A GPO as against plugging a welder with a 15A plug into the same socket?

The only commonality between the 2 sides of a 10 amp GPO are the connection terminals (at the back) - the switches and outlet sockets are separate. So plugging 2400W into each outlet would cause 10 amps to flow through each outlet and switch (not 20 amps). Plugging a 15 amp load into one of these sockets would cause a 15 amps to flow through and outlet and switch (which remember are designed for 10 amps).

So you are running the outlet and switch at 150% of their rated capacity. Maybe it's just me, but that seems pretty logical and not all that difficult to understand.

If we're going to get into the esoterics of the thing, the heaters don't pull 10 amps continuously. They will until the thermostat setting is reached and then they'll shut off until it cools down again. A welder will draw a continuous current whilst it's in operation, so I suppose it depends on how long you use it for at a time as to whether there's any heat build up. If you are welding constantly for an hour, then you will have up to 15A running through the cable for an hour. So presumably the size of the conductor and the installation parameters will determine how much heat builds up in the cable and therefore whether or not there is any risk of melting insulation or fire.

Originally Posted by Vernonv

So you are running the outlet and switch at 150% of their rated capacity. Maybe it's just me, but that seems pretty logical and not all that difficult to understand.

Certainly - in terms of ratings stamped on the packet, no argument there. But evidence has shown that at least one of the two major manufacturers of sockets in Australia uses identically-sized internal conductors for both 10A and 15A sockets. Furthermore, the conducting pin size of a 10A plug is identical to a 15A plug. One has to ask, where does the difference really lie?

Originally Posted by RustyArc

But evidence has shown that

... 1 example is hardly conclusive .

Unless you are SURE that the 10 amp GPO socket you are plugging a 15 amp appliance into is EXACTLY the same as a normal 15 amp socket, then you are taking a risk.
Now are you sure that everyone else out there who is convinced by your presentation of the "evidence" also has a 10 amp gpo capable of handling 15 amps (for all you know they could be using 1950's gpo's or some cheap chinese one) ... the answer is obvious and a much as you wish it to be true, it doesn't make it so.

Originally Posted by silentC

If you are welding constantly for an hour, then you will have up to 15A running through the cable for an hour. So presumably the size of the conductor and the installation parameters will determine how much heat builds up in the cable and therefore whether or not there is any risk of melting insulation or fire.

I'm going to guess you're not a welder?

There is absolutly no way to predict the duty cycle upon which a heater operates - it could be a poorly-insulated, freezing room, it could be outside, it could be a radiant heater that typically doesn't have a thermostat.

A welder, by comparison, has a specific duty cycle. It's on the compliance plate - it tells you the duty cycle for specific welding current over a specific time - and it's not an hour.

For example, a welder with a 15A plug is likely to be a "light-industrial" unit - at it's absolute maximum capacity (which can well be argued is very rarely used) a typical such welder will spec a 30% duty cycle over 10 minutes. That's weld constantly for 3 minutes, cool for 7 minutes.

Silent I am on the same page as you regards the OP's question and the current legality of DIY work in Oz. I have no argument with that so I have nothing to disprove. But you did take someone to task that they could not use low fatalities in OS countries to support a DIY system here. Maybe so, but it is quite valid to say that DIY electrical OS does not correlate with a higher fatality rate. I'm sure those people are arguing the same thing as you they're just not saying it the way you want. So I ask you, you say the OS statistics cannot be used to imply a safer system and promote a similar system here, then you go on to say that you support a DIY system in Australia - On what basis? Clearly it cannot be on a safety basis since you've already said the OS results are meaningless and the high Australian rate indicates tighter restrictions are required. So why do you support appropriately controlled DIY?

Cheers
Michael

Originally Posted by silentC

The thing is Michael, I am not relying upon it to make my point. All I am saying, and all I have ever said, is that currently in Australia it is not legal to DIY. I've also said that some of the suggestions made are irresponsible because they either void the warranty of the appliance; or may not comply with the wiring standard and the person giving the advice has not taken any steps to investigate whether or not they would comply by visiting the site and inspecting the existing installation.

These are facts. If you can disprove any of them, I'd like to hear it.

The debate about whether or not DIY should be allowed in Australia is a separate issue and I've already said I'm more or less in favour of it with appropriate controls. But it's not. So when someone asks a question, the answer, I believe, should be framed along those lines.

Originally Posted by Vernonv

... 1 example is hardly conclusive .

Certainly, but given it's one of the two major suppliers of sockets, it does give pause to wonder about the design and manufacturing decisons made for 10A and 15A sockets. Add to that the identically-sized pins on both - surely if there was a significant issue in socket capacity, the pins would be of a significantly different size?

Now are you sure that everyone else out there who is convinced by your presentation of the "evidence" also has a 10 amp gpo capable of handling 15 amps (for all you know they could be using 1950's gpo's or some cheap chinese one) ... the answer is obvious and a much as you wish it to be true, it doesn't make it so.

I think it's been made abundantly clear in this thread that putting a 15A plug into a 10A socket contravenes the wiring rules. I'm simply trying to drill down past the rules and regulations to ascertain what are the actual risks.

As for the presence of 1950's GPOs or cheap Chinese ones, I'm not entirely sure they are necessarily of inferior design, nor am I sure that if they are inferior, they are not just as likely to fail when presented with a load close to their design limit over a sustained period.

Since we are talking decades here, there's a thing called a "double-adaptor". They were very common in the past, and enabled people to put a 20A load on a single 10A socket. If they were feeling creative, they could stack a couple and really make that socket work. Hence lamenting a 150% of design loading may be trivial in comparison to the real-world loads a socket manufacturer had to deal with.

There was a test done on our sister forum (Renovate Forums - Powered by vBulletin) on the Clipsal and HPM 15 Amp GPO's and the 10 Amp GPO's from both Manufacturers.
Apart from the larger earth pin aperture on both manufacturers' 15 AMP GPO's the size of the connecting "springs"/screws/Cable holes/ was exactly the same as the 10 Amp GPO's.

Just putting that out here.

you could explain exactly what the "horrendous" consequences are, and also explain, fully, how they come about?

hi RustyArc, have a look at my post no 58 on this thread where I explained exactly what you want to know

Originally Posted by RustyArc

..... As for the presence of 1950's GPOs or cheap Chinese ones, I'm not entirely sure they are necessarily of inferior design, nor am I sure that if they are inferior, they are not just as likely to fail when presented with a load close to their design limit over a sustained period....

OK so based on one example and a hunch you are willing to take the risk ... good for you. I would rather base my decisions on the following FACTS:

1. ALL 10 amp gpo's are rated to handle 10 amps.
2. ALL 15 amp gpo's are rated to handle 15 amps.

Over and above that we are guessing.

Now I will say again - unless you are SURE that the 10 amp GPO you are using can handle 15 amps, then you are taking a risk. Suggesting it is ok for everyone else to do such a thing based on the "evidence" you have presented (1 example and some assumptions/hunches) is irresponsible.

There is absolutly no way to predict the duty cycle upon which a heater operates - it could be a poorly-insulated, freezing room, it could be outside, it could be a radiant heater that typically doesn't have a thermostat.

OK it's a poor argument. So I will defer to the wiring standard. What you're proposing does not comply

it is quite valid to say that DIY electrical OS does not correlate with a higher fatality rate

The whole use of the electrical death stats in this argument is false correlation. The stats show the number of people who died from electrocution. You cannot argue that the absence or presence of DIY has any effect on them because it ignores other explanations.

The reason I support DIY is because, quite simply I would like to do my own wiring around the place. It has nothing to do with statistics or anything else.

The "if anything it strengthens it" comment is a non-core argument. I am not using the stats to make any point. I am arguing against the stats being used to make the DIY point.