Current draw via the caravan power supply cord

greyhoundtom · Senior Member

Current draw via the caravan power supply cord

Baz421 · Guru

Hi Tom

It is a more common problem than is normally reported by vanners.

Great that you show/tell how easily it can happen.

Cheers Baz

Jaahn · Guru

Hi greyhoundtom,

Good to see you are keeping an eye on things and looking for the causes. smile

But it does beg the question of how effective the overload trip is. What is it's rating ? It should protect the system at its rated 15 amps. If it is working OK then the cable and the plug and socket are below standard.

jaahn

IMHO the voltage drop because of the undersize cable will not cause more current draw. disbelief

Baz421 · Guru

Jaahn wrote:
Hi greyhoundtom,
Good to see you are keeping an eye on things and looking for the causes.
But it does beg the question of how effective the overload trip is. What is it's rating ? It should protect the system at its rated 15 amps. If it is working OK then the cable and the plug and socket are below standard.
jaahn
IMHO the voltage drop because of the undersize cable will not cause more current draw.

I don't trust ANY overload protection in CP's. Have you seen the condition of some, barely able to move the switch.

oldtrack123 · Guru

Jaahn wrote:
Hi greyhoundtom,
Good to see you are keeping an eye on things and looking for the causes.
But it does beg the question of how effective the overload trip is. What is it's rating ? It should protect the system at its rated 15 amps. If it is working OK then the cable and the plug and socket are below standard.
jaahn
IMHO the voltage drop because of the undersize cable will not cause more current draw.

Hi Jaahn

You are correct voltage drop with most normal appliance does not lead to high current draw EXCEPT for:

Motors, especially if heavily loaded & devices that use switch mode operation

If it is the socket end that is getting & overheating, the van power inlet SHOULD BE REPLACED immediately

A fire could easily occur at that point!!!

All the components, if approved, are designed to carry a small over LOAD & THE 16A OVERLOAD CIRCUIT BREAKER SHOULD

ALLOW FOR THAT

IS the van fitted with an overload circuit breaker, if it has not got one, you should get one fitted NOW before you loose the lot or more to fire.

.

.if it does not have one, all that should not be running at the same time .

Other components ,wiring , main switch ,etc ,in the van could also be overheating, that can, has cause the van to catch fire.

Another frequent cause of plug & sockets overheating ,even far below the rated current is dirty contact faces ,does not take much tarnish to cause over heating

-- Edited by oldtrack123 on Saturday 14th of November 2015 11:33:55 PM

Aus-Kiwi · Guru

Have my steel caps on . To do maths . Lol Its your over 25amps .. The breakers in your van won't protect the extension cords ..
The breaker or fuse in house does.. Heavy duty is mainly the insulation.. The plug has the highest resistance often with some oxidation or crud on plug ..
In any case you know to limit the amount of utensils used at once ..

Delta18 · Guru

I would seriously doubt your fridge is 1500w.

More likely 2 - 300w I would say.

Probably advisable not to run Microwave, electric jug & toaster at the same time.

I have unthinkingly done this in a park and the rcd on the power stand has tripped out.

Cheers Neil

Tomcat · Senior Member

Not to mention how much a hairdryer or electric fan heater pulls.

oldtrack123 · Guru

HI

A 16A OLCB is a16A OLCB ,no matter where it is fitted!!

All vans should be fitted with a 16A OLCB to protect the van wiring & and APPROVED"15A extension lead from over heating

But nothing can protect from fires due to bad contacts!!

Localised heating is a sure indication of a bad connection & should receive immediate attention!

Aus-Kiwi · Guru

Yea seems he has each circuit in van protected only . I hope .. Nothing on sub wires ? Sheesh ..

oldtrack123 · Guru

Delta18 wrote:
I would seriously doubt your fridge is 1500w.
More likely 2 - 300w I would say.
Probably advisable not to run Microwave, electric jug & toaster at the same time.
I have unthinkingly done this in a park and the rcd on the power stand has tripped out.
Cheers Neil

Hi Neil

That would have been the OVERLOAD that tripped out smile

03_Troopy · Guru

oldtrack123 wrote:
Delta18 wrote:
I would seriously doubt your fridge is 1500w.
More likely 2 - 300w I would say.
Probably advisable not to run Microwave, electric jug & toaster at the same time.
I have unthinkingly done this in a park and the rcd on the power stand has tripped out.
Cheers Neil

Hi Neil
That would have been the OVERLOAD that tripped out

No, it was using the knife to get the stuck piece of toast out biggrin biggrin biggrin

Jaahn · Guru

03_Troopy wrote:
oldtrack123 wrote:
Delta18 wrote:
I would seriously doubt your fridge is 1500w.
More likely 2 - 300w I would say.
Probably advisable not to run Microwave, electric jug & toaster at the same time.
I have unthinkingly done this in a park and the rcd on the power stand has tripped out.
Cheers Neil
Hi Neil
That would have been the OVERLOAD that tripped out
No, it was using the knife to get the stuck piece of toast out

Hi smile

IMHO if toasters were invented today they would be banned as they are so potentially dangerous. But most people still stick the knife in to get the toast out without any worry. confuse What about the old ones with the fold down sides. Warm you hands direct on the elements

Jaahn

greyhoundtom · Senior Member

Thanks everyone for your comments, and yes I have some concern that the electrical system in the van is such that an overload switch isn't tripped before this type of thing can happen.
However I certainly do acknowledge that it is my fault in the first place for overloading the power supply cords.

There again it's not difficult to be plugged into a van park system, and have the aircon in the van on as well as unknowingly having the electric hot water system switch on to heating as well as the fridge switch on. Then have lunch in the microwave as well as deciding to have a cuppa with lunch and switch the electric kettle on as well.

The 15 amp lead simply is not able to cope with that sort of load all at once without doing damage somewhere if a safety switch in the van does not cut off the supply.

The van is a Jayco Sterling and the only thing fitted at the supply end of the 230 volt is RCDM -162 which is according to the Internet a 2 pole RCD/MCB 240 V - 30 MA 4.5 KA switch, however I have not been able to ascertain if it even has overload protection and at what current it actually functions.
I hope that someone on here can enlighten me and possibly provide some indication if it needs to be replaced.

greyhoundtom · Senior Member

Some photos of the result with the orange cable the one being I foolishly fitted 15 amp plugs to. The yellow cable is from a dedicated 15 amp lead and on the cut bit of cable it an be seen that the insulation started to deteriorate as it is much thinner on one side, and where the cable started to go brown.

dorian · Guru

www.switchesplus.com.au/detail/rcdm-162
www.switchesplus.com.au/assets/images/productimages/full/RCDM-162.jpg

2 Pole RCD/MCB 16A 30mA 4.5kA

What is the difference between MCB, MCCB, ELCB, and RCCB:
electrical-engineering-portal.com/what-is-the-difference-between-mcb-mccb-elcb-and-rccb

The MCB (Miniature Circuit Breaker) provides 16A overload protection.

The RCD (Residual Current Device) provides 30mA earth leakage protection.

mjt57 · Senior Member

What devices do caravan parks with power have fitted for each site? You'd think that if it sees an overload situation that it'd surely trip.

At a caravan and camping show in Sale (eastern Victoria) on Friday there were a variety of 15a leads, all heavy duty and costing around $65 for a 10m lead. Seemed to be reasonable quality.

03_Troopy · Guru

The pics of the plug on the orange lead look like high resistance joint heating at the the point where the wire connects to the plug pin, or possibly through contact resistance of the pin in a socket with loose contacts.

Roving-Dutchy · Guru

I agree with Troopy the most likely cause is a loose connection in the plug or poor tension in the contacts in the socket in the power pole in the park. Will probably be a loose wire in the plug rather than a the socket. Then again if this happened to two different plugs at the same van park the problem is very likely in the socket in the power pole.
Cheers
David

greyhoundtom · Senior Member

03_Troopy wrote:
The pics of the plug on the orange lead look like high resistance joint heating at the the point where the wire connects to the plug pin, or possibly through contact resistance of the pin in a socket with loose contacts.

I know for certain that the wire was firmly and correctly fitted into the plug, however there have been a couple of situations where I have stayed at showgrounds and the plugs have been a looser fit in the power board than I would have liked.

Its highly likely that the active pin would have heated up in that situation, something else for me to keep an eye on.

greyhoundtom · Senior Member

Thanks for those links Dorian, if the board in the van is supposed to trip when the current is 16 amps it seems to me that it requires replacing.
I simply can't see three plugs all over heating at the active pin at different van parks if the current draw had been limited to 16 amps.

Edited to correct spelling mistake.

-- Edited by greyhoundtom on Sunday 15th of November 2015 12:42:36 PM

Hylife · Guru

Visually "Greyhoundtom", based on the apparent cross-section size of the conductors I would not rate either of those two cords in your photos as safe 15 amp cords.

Whilst traditionally heavier duty cords may have an outer sheath of yellow or orange, there is no requirement as to colour. That is, a yellow or orange power cord does NOT indicate a heavy duty cord or specify a minimum safe current rating.

Worksafe Australia specifies that:-

a 10amp cord should have a minimum of 1 sq mm conductors up to 25 meters and 1.5 sq mm conductors up to 32 meters

a 15 amp cord should have a minimum of 1.5 sq mm conductors up to 25 meters and 2.5 sq mm conductors up to 42 meters

a 20 amp cord should have a minimum of 2.5 sq mm conductors up to 32 meters and 4 sq mm conductors up to 40 meters

Lots of thin strands versus a lesser amount to thick strands may make for a more flexible cord but reduces the maximum current capacities by approximately half.

Additionally, insulation colour or thickness is irrelevant. Insulation standards require 230V cords to have insulation that withstands the maximum wire current (based on cross-section size) up to 500 volts.

Increased abrasion resistance would dictate a thicker outer sheath but unless you know the properties of the material used it is unlikely to provide you with any meaningful insight as to its wear and tear capabilities.

03_Troopy · Guru

greyhoundtom wrote:
Thanks for those links Dorian, if the board in the van is supposed to trip when the current is 16 amps it seems to me that it requires replacing.
I simply can't see three plugs all over heating at the active pin at different van parks if the current draw had been limited to 16 amps.
Edited to correct spelling mistake.

-- Edited by greyhoundtom on Sunday 15th of November 2015 12:42:36 PM

Without knowing what the total current draw was, I would go with the reasoning of contact resistance heating causing the damage. Where the wire is discoloured in one of the pics, how far from the pin was that cross section, and how far down the cable did it extend? if it was caused by excessive current draw, I would expect it to be the same for the full length of cable.

Also, without a gauge/ruler beside the cable in the picture, it is very difficult for any of us to guess at wire sizes by looking at the pics.

greyhoundtom · Senior Member

Just another couple of photos the 15 amp cable that was also found wanting in regard to standing up to the current draw whatever it was that the MCB allowed through without triggering.

photo 2 shows the socket and a section of the wire as close to a tape measure as I could get.

photo 1 is a close up of the plug of the 15 amp cable showing the burn mark where the brown ire connects to the active pin.

While I now believe that the 15 amp power cord purchased as such from a caravan specialist is not up to the standard required, I also have no doubt that there must be other people out there unknowingly large currents through an inferior power supply cable.

-- Edited by greyhoundtom on Sunday 15th of November 2015 01:58:09 PM

oldtrack123 · Guru

Hi Tom

To an experienced eye, each of those pics indicate a loose/ bad connection between cable & the plug pin, At the SCREW joint

THAT is obviously the origin of the heat

or just one other possibility,

WHICH pin is that worst on? , I hope not the earth pin!!

Was the cable showing any indication of overheating along it's full length"

If no sign, then IT is not a cable problem

Re cable size, 15A carrying capacity extension cable must be able carry that current, or it would be against the law to sell it!

Such cable can be as small as 1.5mm Sq & be fully approved for RV/van use up to a max length off 25M

Heavy cables are simply used to minimise voltage drop over longer lengths

Of course ,you are no doubt aware that virtually all the states ban non licensed persons from making up /modifying extension leads etc ,FOR GOOD REASONS!!

-- Edited by oldtrack123 on Sunday 15th of November 2015 02:30:11 PM

-- Edited by oldtrack123 on Sunday 15th of November 2015 02:52:11 PM

oldtrack123 · Guru

greyhoundtom wrote:
03_Troopy wrote:
The pics of the plug on the orange lead look like high resistance joint heating at the the point where the wire connects to the plug pin, or possibly through contact resistance of the pin in a socket with loose contacts.
I know for certain that the wire was firmly and correctly fitted into the plug, however there have been a couple of situations where I have stayed at showgrounds and the plugs have been a looser fit in the power board than I would have liked.
Its highly likely that the active pin would have heated up in that situation, something else for me to keep an eye on.

Hi

If it was overload both or either pin would over heat, as both should be passing exactly the same current.

As previous post ,the origin of the heat appears to be at the cable to pin screwed joint

Suggest you BUY an APPROVED 15A extension lead!!

Remembering that "heavy duty ' may mean heavy duty insulation

Based on length, the cable size for heavy current duty[ to minimize voltage drop, motor starting, etc] is :

1.5mmSq is limited to 15M

2.5mmSqis limited to25M

The extension CABLE WILL have it's size marked at intervals along it's length.[ "x". "x'mmSq]

.

-- Edited by oldtrack123 on Sunday 15th of November 2015 02:57:04 PM

greyhoundtom · Senior Member

Thanks guys, however I realise that for a licensed electrician it is difficult to fathom that a non licensed person may be perfectly capable of modifying an extension cable and do it right every time. Legal or not. Lol

....... and it should be noted that it's clearly visible on the last two photos that a legal non modified 15 amp cable failed to handle the current drawn by the van ......... and it did NOT trigger the MCB fitted to the van.

So I'm still none the wiser in regard to the question "should the MCB be replaced?" as it did not in my honest opinion do the job it's supposed to do, and that is cut the load when excessive current is being drawn. In this case clearly in excess of 16 amp as shown by a legal 15 amp power cord at 15 metres in length starting to overheat at the active pin inside the moulded plug....... and just in case the question comes up the caravan park socket it was plugged into was a recently new installation and, again only in my opinion, a firm fit to the pins of the plug.

mjt57 · Senior Member

Tom, if you're not sure if your van's electrical system is up to the task wouldn't it be safer to have it tested and any components such as MCBs, etc. replaced?

Certainly, whoever modified that lead may not have firmly affixed the wires to the pins. Maybe not tight enough, not enough exposed conductors "wrapped around" the pin's connector, etc..

At work all appliances are PAT tested on a regular basis. We also have a device that we call a "ductor" which measures resistance in cables by pumping a lot of amps through it. Voltage drop is measured.

However, I'd opt for option 1, above. Then look at your leads.

oldtrack123 · Guru

greyhoundtom wrote:
Thanks guys, however I realise that for a licensed electrician it is difficult to fathom that a non licensed person may be perfectly capable of modifying an extension cable and do it right every time. Legal or not. Lol

....... and it should be noted that it's clearly visible on the last two photos that a legal non modified 15 amp cable failed to handle the current drawn by the van ......... and it did NOT trigger the MCB fitted to the van.

So I'm still none the wiser in regard to the question "should the MCB be replaced?" as it did not in my honest opinion do the job it's supposed to do, and that is cut the load when excessive current is being drawn. In this case clearly in excess of 16 amp as shown by a legal 15 amp power cord at 15 metres in length starting to overheat at the active pin inside the moulded plug....... and just in case the question comes up the caravan park socket it was plugged into was
a recently new installation and, again only in my opinion, a firm fit to the pins of the plug.

IF every connection is OK there is absolutely no reason why:

[a] just one connection would heat up .[since both active & neutral carry the same current]

[ b] why the "active??? "would be the only one that heats up excessively.

[c]Is this only occurring at the park supply socket??

Does the plug /socket connection into the van show any signs of overheating??

I just noted ,in your last post that you refer to it as a "moulded" plug, yet previously you said you fitted the plug!

Which exactly is it!!

If a "moulded" plug[ factory wired], it most likely was a faulty lead , with a bad connection, broken strands of cables, at THAT point

Often due to pulling the plug out by the cable, instead of pulling the actual PLUG

The cross sections of cable do not indicate excessive overheating of the core conductors!!

You are playing with fire, & worse

I SUGGEST YOU GET AN LECTRICIAN to check out the whole set including the operation of RCD/mcbo for trip time & current.

Also, if you still have them, show him the cables & plugs.

greyhoundtom · Senior Member

Oldtrack123,

Thanks for your post, unfortunately you obviously did not look at the last couple of photos I posted because you would not have made the comments you did if you had.

All the same I have all ready made up my mind to have the RCD/MBC replaced and to have an RCCB fitted as an added safety level for those times when the van will be plugged into a generator and be without a negative/earth system.

Thanks to all those who took an interest in this subject.

-- Edited by greyhoundtom on Sunday 15th of November 2015 04:38:06 PM