So like me you thought it was OK to plug a 10amp device into a 15amp outlet.

[aussiblue]

Like most people you probably all know you should not try to plug a 15amp device into a 10amp outlet or modify the cord or worse the plug so you could. But you also probably assumed like many, including me until today, that it was OK to plug a 10amp plug or device into a 15amp socket as they normally fit and appear to work fine. But I learnt today this is actually not the case.


I have a double 15amp outlet in my shed I had installed some years ago (when I bought my car lift) by an electrician with both separately fused so I could use both the car lift and a mig welder in my shed. I recently bought a Jamec Penn Wal Mounted tyre inflater to use with my Woodstar CP16 wall mounted compressor and decided that the most convenient place to hang this in terms of using it to fill tyres and to avoid having to use long extension cords or long hose lines was alongside the 15amp twin outlet and utilise that outlet with these two 10amp devices. However, when I came to plug them in I found that these 15 amp outlets were safety shuttered so that unless a 15 amp earth was in the earth pin socket access to active and neutral were blocked. Enquires to the Bunnings Workshop site about if suitable adapters existed initially resulted in advice that “I've spoken with HPM, and their HPM 15A Double Powerpoint will accept a 10A plug. Alternatively, it might be worth installing a 10A outlet next to your 15A” but subsequently the revised advice: “However, speaking with Deta, they have strongly advised that you do not force a 10A plug into their 15A socket as the shutters have been introduced to exclude 10A plugs; the reason is as follows: A circuit designed for 15A devices has suitable overload protection designed for them. It's best to run 10A devices on a circuit designed for them so the overload protection trips immediately if something goes wrong. A failing 10A device on a 15A circuit might not trip it immediately. If, for some reason, the overload is not triggered and the 10A cable or device overheats, it could be a fire risk.” On reflection this makes sense and so I guess it’s actually not really OK after all to plug 10amp devices into 15 amp outlets and I will be re-siting my wall mounted devices near one of the 10 amp outlets on the other side of the workshop.

Adding some more 10 amp outlets would be an expensive exercise for me as my existing switchboard is full so the last electrician I used said that if I wanted to add anything more it would have to be completely replaced or an additional sub- board added and, having been through that once to replace the original asbestos backed board, I know that gets to be a very expensive exercise that I cannot justify. I don’t really want 15amp cords or plugs on the inflator and compressor as that would prevent their use with normal 10amp outlets and void the warranty. For safety reason I also don’t want to suspend cords or air hoses over the top of my car lift. What I really need is a plug in safety switch that has both RCD and overcurrent protection; something like this but with 15amp pins: https://www.bunnings.com.au/arlec-si...witch_p7050029

In any event, I though other members would like to know about this little known safety issue. Most websites when I searched, wrongly it now seems, advise it is fine to plug a 10amp device into a 15 amp outlet.

[Charliewool]

Ground down plenty of 15amp earth pins, but never thought you’d need to “add metal” to a 10amp for it to work in a 15 outlet…

[Franco Cozzo]

Originally Posted by Charliewool

Ground down plenty of 15amp earth pins, but never thought you’d need to “add metal” to a 10amp for it to work in a 15 outlet…

Just cut it off completely, the earth is only there for the safety devices anyway

[pottery beige]

Originally Posted by Franco Cozzo

Just cut it off completely, the earth is only there for the safety devices anyway

electrical safety is over rated

[aussiblue]

Ground down plenty of 15amp earth pins, but never thought you’d need to “add metal” to a 10amp for it to work in a 15 outlet…

I now have this picture in my head of Charliewool wrapping layers of foil around the earth pin on a 10amp plug and...

[Citroënbender]

So it really just requires the reverse of ye olde “15 into 10” short extension lead.

[redxm]

If your that concerned about electrical safety dont by Deta junk from Bunnos

Whats the breaker rated at? 16A is fine for a 10A outlet, just swap the outlet

[foxtrot3]

Originally Posted by aussiblue

Like most people you probably all know you should not try to plug a 15amp device into a 10amp outlet or modify the cord or worse the plug so you could. But you also probably assumed like many, including me until today, that it was OK to plug a 10amp plug or device into a 15amp socket as they normally fit and appear to work fine. But I learnt today this is actually not the case.


I have a double 15amp outlet in my shed I had installed some years ago (when I bought my car lift) by an electrician with both separately fused so I could use both the car lift and a mig welder in my shed. I recently bought a Jamec Penn Wal Mounted tyre inflater to use with my Woodstar CP16 wall mounted compressor and decided that the most convenient place to hang this in terms of using it to fill tyres and to avoid having to use long extension cords or long hose lines was alongside the 15amp twin outlet and utilise that outlet with these two 10amp devices. However, when I came to plug them in I found that these 15 amp outlets were safety shuttered so that unless a 15 amp earth was in the earth pin socket access to active and neutral were blocked. Enquires to the Bunnings Workshop site about if suitable adapters existed initially resulted in advice that “I've spoken with HPM, and their HPM 15A Double Powerpoint will accept a 10A plug. Alternatively, it might be worth installing a 10A outlet next to your 15A” but subsequently the revised advice: “However, speaking with Deta, they have strongly advised that you do not force a 10A plug into their 15A socket as the shutters have been introduced to exclude 10A plugs; the reason is as follows: A circuit designed for 15A devices has suitable overload protection designed for them. It's best to run 10A devices on a circuit designed for them so the overload protection trips immediately if something goes wrong. A failing 10A device on a 15A circuit might not trip it immediately. If, for some reason, the overload is not triggered and the 10A cable or device overheats, it could be a fire risk.” On reflection this makes sense and so I guess it’s actually not really OK after all to plug 10amp devices into 15 amp outlets and I will be re-siting my wall mounted devices near one of the 10 amp outlets on the other side of the workshop.

Adding some more 10 amp outlets would be an expensive exercise for me as my existing switchboard is full so the last electrician I used said that if I wanted to add anything more it would have to be completely replaced or an additional sub- board added and, having been through that once to replace the original asbestos backed board, I know that gets to be a very expensive exercise that I cannot justify. I don’t really want 15amp cords or plugs on the inflator and compressor as that would prevent their use with normal 10amp outlets and void the warranty. For safety reason I also don’t want to suspend cords or air hoses over the top of my car lift. What I really need is a plug in safety switch that has both RCD and overcurrent protection; something like this but with 15amp pins: https://www.bunnings.com.au/arlec-si...witch_p7050029

In any event, I though other members would like to know about this little known safety issue. Most websites when I searched, wrongly it now seems, advise it is fine to plug a 10amp device into a 15 amp outlet.

Hi. Check the circuit breakers in the main board, you may find they are all 20amp rated for the power circuits. If so a sparky may be able to put a sub board in the shed using the existing wiring to the shed. Cheers MD

[aussiblue]

So it really just requires the reverse of ye olde “15 into 10” short extension lead.

But prefaced by the words "equally illegal and likely nearly as dangerous..."

Having known several people and knowing of other people that have been fatally electrocuted i have a more than healthy respect for electricity. But I also accept a professional electrical may not always be the answer noting:

a) There was an article and ongoing discussion over some months in Electronics Australia magazine about the issue some years ago noting the in those countries (or some States in some countries like USA) that either allowed home owners to do their own wiring or had schemes that gave limited licences after training to home owners the rate (not just the number) of electrocution accidents was lower in the home owner amateur electricians than in professional electricians;
b) many of the recorded mortalities from electrocution involve professional electricians or their apprentices working on live wires where their co-worker or boss has tuned the power back on or they had been through the routine so many times the though they had turned power off at the main switchboard but had not (and similar "familiarity builds contempt issues");
c) when I checked the power points in my then newly built home in the early eighties with a simple three LED Clipsal tester, I found that my than half my power points were not earthed as the electrician or whoever he had install them had not stripped any insulation off the earth wire and had seemingly wrongly assumed that screwing down the earth terminal scree hard would piece the wire but this had not happened; I do wonder how many other homes built by what was then WA's largest home builder still have such faulty unearthed sockets in them; and
d) the electrician that installed the 15 amp outlets in my shed had his wife call me back a few days later to see if he had reinstalled the screws holding the board onto the wall; he had not screwed the board in again but at least he had a sudden subconscious reminder though I wonder how often similar things happen that aren't remembered at all.

[aussiblue]

Check the circuit breakers in the main board, you may find they are all 20amp rated for the power circuits. If so a sparky may be able to put a sub board in the shed using the existing wiring to the shed. Cheers

They can, but so far not at a price that equates to the marginal additional convenience of using the slightly closer and more easily accessible from that side of the shed power points. If it becomes an annoying inconvenience I will reconsider this option or perhaps more likely re-site the inflator and compressor to the power points in the carport under the house roof.

[Warrenk]

Never had an issue plugging a 10amp plug in a 15a GPO. I am a licensed electrician and never heard it is illegal to do so. The earth pin on a 10amp plug should be able to open the shutter on a 15a GPO.

[BENT_8]

2 pin plugs?

I see online pics show the Woodster with a 2 pin plug.

[whynot]

Originally Posted by Warrenk

Never had an issue plugging a 10amp plug in a 15a GPO. I am a licensed electrician and never heard it is illegal to do so. The earth pin on a 10amp plug should be able to open the shutter on a 15a GPO.

Yup, I agree with Warrenk. I too am a licenced electrician.

The design of the 10 amp, 15 amp, 20 amp, 25 amp, and 32 amp single phase outlets is that the small can go into the bigger, but not the other way around. The physical interlock is the size and shape of the earth pin that increases with size. The 10 amp plug can go into (and open the shutters) of the 15 amp.

See https://en.wikipedia.org/wiki/AS/NZS_3112 for pictures.

Not sure why DETA decided to depart from a very long standing practice.

Those arguing about the upstream protection size are barking up the wrong tree here as well. Most domestic power circuit are either protected by a 16 amp fuse or a 20 amp circuit breaker. (And, these days, hopefully everything is also covered by an RCD.) If one looks at the operating characteristic of both, in the overload part of the curve, they are about the same. The 20A circuit breaker is much, much, better in clearing short circuits than the 16 amp fuse.

When putting a 10A plug into a 15A socket, thermal overload is not a problem as the device is limited to under 10A. The only concern is having sufficient low impedance as to clear a fault using the overcurrent part of the protective curve. Given the size of the conductor in the appliance, this is not a concern either as the cable fault rating for 1mm2 flexible is 1.2x104 A²s

There are a few options ...

1) Depending on the size of the wiring and the selected circuit protection to the existing 15A outlets (e.g. 4mm cable protected by a 20A CB per 15A outlet) it is permissible under Table C9 (page 484 of AS3000) to have up to eight additional 10A socket-outlets in that circuit (under certain circumstances).

2) There are legit 15A socket-outlet to 10A plug adapters that incorporate a miniature 10A CB. This might be a cheaper option than getting a sparkie out to fix the existing 15A outlet or installing a 10A beside it.

[X-AHH]

Originally Posted by whynot

Yup, I agree with Warrenk. I too am a licenced electrician.

The design of the 10 amp, 15 amp, 20 amp, 25 amp, and 32 amp single phase outlets is that the small can go into the bigger, but not the other way around. The physical interlock is the size and shape of the earth pin that increases with size. The 10 amp plug can go into (and open the shutters) of the 15 amp.

See https://en.wikipedia.org/wiki/AS/NZS_3112 for pictures.

Not sure why DETA decided to depart from a very long standing practice.

Those arguing about the upstream protection size are barking up the wrong tree here as well. Most domestic power circuit are either protected by a 16 amp fuse or a 20 amp circuit breaker. (And, these days, hopefully everything is also covered by an RCD.) If one looks at the operating characteristic of both, in the overload part of the curve, they are about the same. The 20A circuit breaker is much, much, better in clearing short circuits than the 16 amp fuse.

When putting a 10A plug into a 15A socket, thermal overload is not a problem as the device is limited to under 10A. The only concern is having sufficient low impedance as to clear a fault using the overcurrent part of the protective curve. Given the size of the conductor in the appliance, this is not a concern either as the cable fault rating for 1mm2 flexible is 1.2x104 A²s

There are a few options ...

1) Depending on the size of the wiring and the selected circuit protection to the existing 15A outlets (e.g. 4mm cable protected by a 20A CB per 15A outlet) it is permissible under Table C9 (page 484 of AS3000) to have up to eight additional 10A socket-outlets in that circuit (under certain circumstances).

2) There are legit 15A socket-outlet to 10A plug adapters that incorporate a miniature 10A CB. This might be a cheaper option than getting a sparkie out to fix the existing 15A outlet or installing a 10A beside it.

I understood everything that you posted and we all understand that you are a sparky (Great achievement by the way) but too much information will confuse people who aren't.

[FoxtrotGolfXray 5.0]

Originally Posted by whynot

.
Those arguing about the upstream protection size are barking up the wrong tree here as well. Most domestic power circuit are either protected by a 16 amp fuse or a 20 amp circuit breaker. (And, these days, hopefully everything is also covered by an RCD.) If one looks at the operating characteristic of both, in the overload part of the curve, they are about the same. The 20A circuit breaker is much, much, better in clearing short circuits than the 16 amp fuse.

I take it that the bold comment was directed at me. At least you're clued in to my concern being about fault current and not normal operating draw (that answers b0son's question). Appreciate the explanation you've offered, wn.

I'll admit that this is not my area of expertise. But I do have some knowledge of the subject. I'm an electrical engineer (I can hear all you sparkies groaning right now ) although I haven't really practiced in that space for a few years now, anf I have undertaken electrical inspectors training (for those who don't know, these are the folks that check on the work licenced sparkies complete), although, for full disclosure, that was done years ago and in never sat the exam, so my competency wasn't assessed. One thing I did learn though, is that even the soarkies on our course had a lot of different views on some of the trickier elements of as300 and a lot held incorrect views according to our trainer. A bit like asking people on these forums questions about some of our road rules

And I also did a stack of research when I was setting up my 240v system for my camper trailer, and I specifically recall reading (perhaps as3001? ) that you can't plug in a 10a plug and lead into a 15a socket outlet at a caravan park so I ended up getting one of these

https://www.discounttrader.com.au/pr...wer-block-box/. (that might help blue, but he probs won't need the ip54 rating)

Perhaps that is what I'm thinking of. I don't have access to the standards at the moment, so I'll bug out until I get a chance to look at them, and chat to our electrical compliance officer next week. I'm not above admitting I've got it wrong, if that turns out to be the case, and I'll retract my previous posts if so.

[whynot]

Originally Posted by FoxtrotGolfXray 5.0

I take it that the bold comment was directed at me.

Never, ever, let the opportunity to ruffle the feathers of an electrical engineer go by ... (with a really big nudge and a wink).

Originally Posted by FoxtrotGolfXray 5.0

although I haven't really practiced in that space for a few years now

Yeah, me too. But I still have my ticket and occasionally dabble with the tools.

Originally Posted by FoxtrotGolfXray 5.0

... that you can't plug in a 10a plug and lead into a 15a socket outlet at a caravan park

That surprised me. I can clearly recall being taught by the TAFE instructors that the design of a 15A outlet was specifically done to allow the acceptance of a 10A plug. When this topic came up, my first impression was that there had been a standard change recently that I had missed. Unfortunately (and this really makes me grind my teeth), access to AS3112 requires a payment of $250. After quite a bit of digging around, I am reasonably sure that this hasn't changed for this use case. But, if I am wrong, I will get an admin to edit my post.

Originally Posted by FoxtrotGolfXray 5.0

At least you're clued in to my concern being about fault current

I am struggling to understand why you would be concerned about the potential change to the loop and Z-loop impedance characteristics. Most domestic circuits are protected by a 20A circuit breaker. Most dedicated 15A socket-outlets are also protected by a 20A circuit breaker as well. The chief difference is the permissible number of outlets per circuit under Table C9. A 1mm2 conductor inside an appliance has to withstand the same I2/T curve in both examples.

This AS3008 on-line calculator is a handy way to check. Tick the boxes for short-circuit current rating and loop impedance.

https://www.jcalc.net/cable-sizing-calculator-as3008

While we are at it, there is also a legitimate way to connect a 15A plug into a 10A socket - provided - there is a 10A circuit breaker between the plug and socket. This limits the maximum draw to 10A, and so can be legally installed in the 10A outlet. A use case for this is when a caravan is parked at home and it just needs trickle supply for the fridge and maybe a few lights.

As an aside, I started to write up a technique on how to correctly apply lubrication to a 15A outlet. But it started to read like a novel found at the back of the shop, and I though better of it.

[FoxtrotGolfXray 5.0]

Yes, people don't appreciate that a circuit breaker is really there for the protection of the wiring. If the device, and therefore wiring, is designed to take 10 amps, but the circuit protection is designed to trip at a nominal 15 amp, then the 10 amp wiring is not protected at the rating it is designed for.

Naturally, there is always margin in the design so you may be able to get away with it most if the time, but it won't work all the time.

[aussiblue]

I see the Clipsal ones as with many other brands except perhaps HPM also now have this safety shutter that inhibits the insertion of a 10amp plug into their 15 amp socket so I am guessing there may been a recent change to AS/NZS 3112. the standard for AC power plugs (male) and sockets (female) requiring it.

[aussiblue]

I see online pics show the Woodster with a 2 pin plug.

Nah; my, BiG W I think originally sourced, Woodstar came with and has a 10 amp three pin plug. Perhaps the ones sold in their home country Germany or elsewhere had a two pin plug. If I could find another brand of compact wall mounted compressor with and 15 amp I might buy it, I already have several larger floor and trolley tank mounted compressors but this is great to leave on the wall not tripping you over or invading significant head room or floor space where you park the cars for tyre inflation.

[simon varley]

sounds like a 'theoretical risk' that legislation has 'fixed'

[FoxtrotGolfXray 5.0]

Originally Posted by simon varley

sounds like a 'theoretical risk' that legislation has 'fixed'

Hardly a theoretical risk. Think of it like pairing a drive shaft rated at 200nm (figures picked for illustrative purposes only) with an engine that can output 300nm (the drive shaft is the cable, the engine is the circuit breaker in this comparison). The drive shaft will have margin built into its design so some shafts may handle the 300nm if the operator demands it from the engine, which may not ever happen) but there is also the possibility that the drive shaft may not handle the torque of demanded, in which case all sorts of undesirable implications could occur.

It's a safety issue first and foremost. That's also why it's a requirement of as3000 and has been for quite some time, IIRC.

[roKWiz]

They've been selling approved 15amp to 10amp leads for the RV industry for years.

[Warrenk]

Originally Posted by roKWiz

They've been selling approved 15amp to 10amp leads for the RV industry for years.

The adaptors are so you can plug a 15a lead into a 10a GPO. Won't have any effect on what the subject is about.

[roKWiz]

Originally Posted by Warrenk

The adaptors are so you can plug a 15a lead into a 10a GPO. Won't have any effect on what the subject is about.

and the subject is about running 10amp appliance from 15amp power point or did I miss something.

[b0son]

Originally Posted by FoxtrotGolfXray 5.0

The drive shaft will have margin built into its design so some shafts may handle the 300nm if the operator demands it from the engine, which may not ever happen) but there is also the possibility that the drive shaft may not handle the torque of demanded, in which case all sorts of undesirable implications could occur.

So there are 10amp devices that if they see a 15A source, will accept that 15A and burn out? I'm no sparkie, but I thought a device is designed to take what it needs, not what's available?

[X-AHH]

Originally Posted by b0son

So there are 10amp devices that if they see a 15A source, will accept that 15A and burn out? I'm no sparkie, but I thought a device is designed to take what it needs, not what's available?

The current rating of the power point is irrelevant as they have no current limitations apart from their internal components ability to safely pass the current through to the appliances. The protection device at the switchboard dictates how much current can be delivered through the cable and power point. For this reason, 10 and 15 Amp power points can share the same circuit and protecting device. As previously mentioned by another sparky here, the fuse, circuit breaker etc are intended to protect the cable, nothing else.

[Interceptor]

1: your average bunnings counter jumper is hardly a reliable source.
2: DETA arent exactly a credible source either
3: safety shutters were introduced to save little johnny from sticking a fork into a GPO (power point)
4: get a licensed electrician to install a double 15a GPO that doesnt have the idiotic safety shutters, they exist.

[aussiblue]

1: your average bunnings counter jumper is hardly a reliable source.
2: DETA arent exactly a credible source either
3: safety shutters were introduced to save little johnny from sticking a fork into a GPO (power point)
4: get a licensed electrician to install a double 15a GPO that doesnt have the idiotic safety shutters, they exist.

1. It wasn't a counter jocky it was the one of the staff that run the Hardware Forum now called Bunnings Workshop and he consulted HPM and DEETA and I assume Bunnings own technical staff.
2. DETA and HPM both make 15 AMP outlets so at least they would have the AS/NZS 3112 and all technical manufacturing and safety knowledge required at their fingertips.
3. But in this case also to prevent 10 amo plugs being inserted into 15 amp sockets.
4. Perhaps, but I will see where all this goes first.

[X-AHH]

Normally the shutters should move out of the way with a 10 Amp plug but if a bit sticky, they might need some help. With the circuit breaker off, spray the 3 holes where the plug gets inserted with silicone dry lubricant and wait for it to dry properly. Insert a 15 Amp plug several times to get the shutters moving easily again. Try the 10 Amp plug. Switch the circuit breaker back on.

Hope this works, good luck mate.

[Interceptor]

Originally Posted by aussiblue

1. It wasn't a counter jocky it was the one of the staff that run the Hardware Forum now called Bunnings Workshop and he consulted HPM and DEETA and I assume Bunnings own technical staff.

Whats the bet they dont know AS300 chapter and verse, that theyre not licensed electricians, and are only regurgitating what their computer says?

Originally Posted by aussiblue

2. DETA and HPM both make 15 AMP outlets so at least they would have the AS/NZS 3112 and all technical manufacturing and safety knowledge required at their fingertips.

Reading something, and being able to understand and apply it are two different things.

Originally Posted by aussiblue

3. But in this case also to prevent 10 amo plugs being inserted into 15 amp sockets.

Which has no practical or required purpose.

Originally Posted by Warrenk

The adaptors are so you can plug a 15a lead into a 10a GPO. Won't have any effect on what the subject is about.

Originally Posted by roKWiz

and the subject is about running 10amp appliance from 15amp power point or did I miss something.

10A plug *should* plug into a 15A socket quite happily, but a 15A plug is physically incapable of being inserted into a 10a socket because of the oversized earth pin.

Originally Posted by b0son

So there are 10amp devices that if they see a 15A source, will accept that 15A and burn out? I'm no sparkie, but I thought a device is designed to take what it needs, not what's available?

Nope, a device will only draw as much current as its rated at regardless of the supply.
The source will supply as much current is demanded of it up to the capacity of the fuse or circuit breaker.

Originally Posted by whynot

2) There are legit 15A socket-outlet to 10A plug adapters that incorporate a miniature 10A CB. This might be a cheaper option than getting a sparkie out to fix the existing 15A outlet or installing a 10A beside it.

Wrong way around, OP needs a 15A plug and 10A socket.

Originally Posted by whynot

https://www.safetyquip.com.au/produc...screened-lead/
https://www.auselectronicsdirect.com...nd-up-reel-15a

Both of which are really expensive ways of having a simple, short 15A extension lead that will happily accept a 10a plug

speaking of which...

Originally Posted by FoxtrotGolfXray 5.0

Note several considerations of these Rules:
1) You are permitted to use a flexible cable to supply "transportable structures" which includes motor vehicles being used for accomodation.
2) This cable is required to be rated at 15A, be of "heavy duty" and not less than 10m long.

I wouldve thought that the requirement would specify a maximum cable length, not minimum. I know my local mitre 10 sells HPM branded 15a extension leads specifically labelled for caravan connection.

Originally Posted by gkhn

I always used this on a 10amp power outlet while testing faulty devices. That way the building's curcuit/fuse/breaker is isolated and protected in case the device pulled more than 10amps.

The buildings 15a circuit will happily supply a faulty device with up to 15 amps of current without problem and will do so with an appropriate safety margin.
The faulty device, however, may not cope so well.

Originally Posted by aussiblue

The also said that they were puzzled as to why DETA would produce a 15amp socket that could not take a 10amp plug. So this certainly raises questions about the advice from DETA or even perhaps to what extent their products meets Australian standards.

Goes back to what I said about DETA not being a credible source, and my rebuttal to your comment.
Theres a reason no reputable electrical wholesaler stocks DETA.

Ultimately, the quickest, easiest and most affordable answer to your question would be to use the shortest 15 amp extension lead you can find as an adapter.