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Post Info TOPIC: Maximum power which can be drawn from the extension lead.


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Maximum power which can be drawn from the extension lead.


Hi guys, just wondering what type of incoming circuit breaker protects the 15A extension lead on your vans? in other words if i run kettle plus aircon plus oven all at once, will the circuit breaker trip first or will i melt the incoming 15A extension cord from the site outlet to the van?  



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The breaker should trip .

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some have told me that they have a 20 A breaker installed but i dont know what most vans have installed, anyone?



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Good Evening Hot Water.

Caravan Parks are 15 Amp. You should be able to run all you're devices at once, however if you do go into overload your van will trip first.

Regards.

Hetho.



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*Ensure* the extension lead is not coiled on a drum or similar - any excess length should be scattered under the van in order to allow heat to dissipate.

Caravan park feeds are fused at 15A so if you exceed that level the breaker will, eventually, trip.

NB. Circuit breakers and fuses do not trip at 0.001% over-current they have a time/overload curve but any more than a few percent overload should see them trip in a reasonable time frame to protect the wiring.



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thanks. so the site circuit breaker will normally protect the extension lead on overload?



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Hot Water wrote:

thanks. so the site circuit breaker will normally protect the extension lead on overload?


 Yes but with the modern and correctly wired and fused van the circuit breaker in the van will normally trip before the park circuit breaker.



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so does the incoming extension cable normally feed into 1 dedicated main circuit breaker of 16A or 20A at the van?



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This link shows that circuit breaker (CB) trip time could be a while
testguy.net/content/197-Characteristics-of-Circuit-Breaker-Trip-Curves-and-Coordination

It seems to show that current at double/triple the CB rating would take several seconds to trip.

If that is the case, I can certainly see how fires start from hot cables etc .

I expected the CB would trip quickly if the CB rated current was exceeded by a small amount say 20%

Other interest , is I found this 10 am 15 amp convert device mentioned ...

www.campsmart.net.au/buying/safe-caravan-power-supply-rcd-units/


About the original question
A kettle can take 10 amps by itself.



-- Edited by PeterX on Saturday 1st of December 2018 10:00:53 PM

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Looking at the photo in the link the socket has a 15 amp earth. Then the that power board is plugged into 10 amps.

To make it clear you do not get 15 amps out of a 10 amp circuit, also with the possibility of putting a 10 amp extension cable between the 15 amp power board & a wall socket (power supply).

So they have stuck a 10 amp circuit breaker in the 15 amp power board so you will only have 10 amps available through your 15 amp circuit in the caravan.



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If the lead is an approved one ? It will take 15 amp with ease . If cable is 2.5mm sq., Plugs and sockets deteriate over time . These are what will fail .

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The reason they put a 10 amp circuit breaker in it, is if some idiot puts a 10 amp extension lead between it and the wall, the extension lead won't be overloaded.



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Hetho wrote:

Good Evening Hot Water.

Caravan Parks are 15 Amp. You should be able to run all you're devices at once, however if you do go into overload your van will trip first.

Regards.

Hetho.





I have no professional knowledge but I would have thought the aircon (1600 watts + kettle 2500 watts ?) without oven on together would trip a 15 amp breaker I maybe wrong so stand to be corrected

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CB trip time would depend if devices are drawing full rated power all, at the same time.

Example A small kettle may be 1KW. Or the kettle may just be drawing power for 2 minutes.

It also depends on the type of CB, as to how quickly the trip when rated trip current is exceeded.

The "simplified" CB trip (log graph) curve shows that double the rated trip current could be drawn for 10 seconds or a bit longer.

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Hot Water wrote:

Hi guys, just wondering what type of incoming circuit breaker protects the 15A extension lead on your vans? in other words if i run kettle plus aircon plus oven all at once, will the circuit breaker trip first or will i melt the incoming 15A extension cord from the site outlet to the van? 


I can assure you that leads that are constructed to meet the regulations are robust enough to stand more current than that that will activate a 15/16 A breaker. There has been some talk above about breakers being a little slow to trip under certain circumstances but if you have connected your van properly the leads will stand this bit of overload. In some parks, a couple of outlets may be protected by a 25 or 30 A breaker. If there is a problem in your van that does not activate your breaker the lead will still survive until that 30 A breaker trips.

The reason that the leads will survive severe overloading is that the fusing current of the cable used in our leads is many times the rated operating current. The standards specify cable for each size lead such that a lead that is the maximum length for that particular cable will not have more than 5% volts drop when operated at its maximum current. If say a 25 metre 15 A lead was constructed with cable that had a fusing current of 30 A then many large current items that you tried to operate in your van would not work properly because the voltage drop would be too high to provide sufficient power for that item. - You can rest easy.

When I said "if you have connected your van properly" above, that means rolling the leads out so the complete length is in free air. If you have your lead coiled up then it is possible for the insulation to melt with a current of less than the rated current flowing through it. All leads drop a little voltage with the current flowing through them. That causes a little power loss and thus a little bit of heat heat. That power loss is enough to heat and melt the insulation if the heat cannot escape from the cable. The outer layers of the cable prevent the heat from escaping.



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thank you for your reply. what incoming breaker or combined value do most vans have which might trip on overload?



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Keep in mind but dont depend on it . The house or supply will have protection too . Breakers work faster than old fashioned fuses . Your thinking tho ! Try telling my Mrs you cannot run toaster,electric jug, airconditioner at the same time !

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Your thinking tho ! Try telling my Mrs you cannot run toaster,electric jug, airconditioner at the same time ! 

you are right, thats what will happen at my place.



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Hot Water wrote:

thank you for your reply. what incoming breaker or combined value do most vans have which might trip on overload?


 All vans have a 15 A input. Most parks can supply that 15 A to you. The power available from a 15 A supply is 3.6 kW or in other terms 3,600 W. Gather the appliances you intend to operate at the same time. You just add the power ratings that are listed on the devices information plates together. If the power ratings exceed 3.6 kW then you rethink your intentions.

If you are wishing to use a heater or air conditioner whilst preparing a meal you may have to reconsider and turn it off for a while whilst you are using all the other appliances. If you are using a heater with a few power settings you may just have to switch the heater down to its lowest level to be able to operate it.

When I say most parks can supply you a full 15 A of current there are some that can not whilst you are sharing the power between two sites. There are quite a few parks that were built;t with 10 A outlets. They have had to refit the power outlets with 15 A power points. The rules allow them to supply 2 or more power points from one breaker in the power control box. Two 10 A power points may have been supplied via a 20 or 25 A breaker. When the higher rated power points were fitted the cable may not have been heavy enough to allow a higher rated breaker to be fitted so the old one has been retained. If you encounter this situation you just have to liaise with your neighbour to cook your meals at different times. Also if you both are using 2.4 kW heaters (10 A pwer draw) and you both wish to use them on high power, then if you are sharing a 20 A breaker your fridges may be enough extra power that will trip the breaker. This is one of the reasons we only purchase 1.8 kW (1800 W) heaters for use in the van.

The rules allow for that situation. There is no good winging about the situation. All you can do is to move on if you can not live with the situation.



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thanks Peter for your informative post. So it seems all vans have a 16A main input Breaker, as i dont think 15A MCBs are commercially available?



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No, 15 A breakers were available. If they are no longer available I am not sure if the number of vans with 16 A ones would be in the majority yet.

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Yep 3.600 div 240 = 15 .

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PeterD wrote:

No, 15 A breakers were available. If they are no longer available I am not sure if the number of vans with 16 A ones would be in the majority yet.


 so as per the aussie regs is the van controlled by just 1 x 15 or 16A breaker on the main incoming fixed wiring so that the extension cord is protected in worst case overload? 



-- Edited by Hot Water on Monday 3rd of December 2018 07:54:48 PM

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Aus-Kiwi wrote:

Yep 3.600 div 240 = 15 .


 To come up to date with your regs 3,600 div 230 = 15.6217 - hence the 16 A breakers.



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PeterD wrote:

 


 All vans have a 15 A input. 


Can we say "most" instead of "all" please? :)

It is not so long ago that 15A was required and prior to that 10A was a legitimate choice and the change was not retrospective, so there will be some vans with 10A about.

Much more sensible IMHO to have 10A if you don't need 15A.

Cheers,

Peter



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PeterD wrote:
Aus-Kiwi wrote:

Yep 3.600 div 240 = 15 .


 To come up to date with your regs 3,600 div 230 = 15.6217 - hence the 16 A breakers.


"Standard" voltage is now 230, not 240V and allowable voltage variations can take that quite a bit lower than that, so 16A may be quite a bit less that 3,500W.

Cheers,

Peter



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the 3600W rating of this 15A extension cord is called its "Nominal Rating Value" as it is approximate in nature. In reality it can take quite a bit of abuse and should run all day comfortably at 20A if not sitting in direct sun.

so does anyones van have a single 16A breaker used for a main switch to isolate all power coming in to the van?

 



-- Edited by Hot Water on Monday 3rd of December 2018 08:08:24 PM



-- Edited by Hot Water on Monday 3rd of December 2018 10:20:52 PM

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My voltage is way over 230v but why argue for the sake of it . Everyone knows what 240 means . Dividing = amps . Whatever voltage . Ok your decks bigger . Sheesh

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We are usually around 245 to 247 volts according to my true RMS meter. Drops to 244 during peak evening load.



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Aus-Kiwi wrote:

My voltage is way over 230v but why argue for the sake of it . Everyone knows what 240 means . Dividing = amps . Whatever voltage . Ok your decks bigger . Sheesh


 http://www.ewh.ieee.org/r10/nsw/subpages/history/Australian-AC-Line-Voltages.pdf

The point is that your 16A might only give you about 3,300W, so if you unexpectedly pop your circuit breaker this could explain why.

Just keep your personal comments to yourself please.

Cheers,

Peter



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