Inverter plugs

Stewart · Senior Member

Inverter plugs

Peter_n_Margaret · Guru

Stewart, our inverter is hard wired and powers about 8 power points through the van. That power is protected by a hard wired RVD.
We can not connect to outside power at all.
Plugging a power board (or any multiple power points) into an inverter has some serious safety risks if you use anything except double insulated appliances. In the unlikely event of faults it is possible to be electrocuted by touching two appliances at the same time. Even a very small 240V inverter has enough power to kill.
Take great care.
Cheers,
Peter

Terryt · Veteran Member

I have a 300w and a 360w inverter. Both are connected all the time but normally switched off. One is near the batteries I have an extension cord running to a wall mounted socket. Also have the option to plug in a small 240v battery charger to charge start batteries. The other inverter is wall mounted and when I want to use it I just plug in whatever and turn it on. Use that one much more than the harder to get at one.

Tony Bev · Guru

Hi Stewart
I am not an electrician

I have a 300/600 watt (300 normal 600 peak), 12 volt DC to 240 volt AC Inverter

As I only use it to charge up my cordless drill, and cordless impact wrench batteries
(I have, just to make sure it can do so, charged my laptop, and phone, from this Inverter)
I just plug the Inverter into a ciggy type socket

The ciggy type socket, is connected direct to the house batteries, via a 10 amp fuse, at the battery

I keep the inverter, inside its original packing box, and packed away, in a cupboard, as I find that I seldom use it
I find that I can charge my laptop, phone, camera, rechargeable AA batteries, with the 12 volt ciggy socket system

My theory is, is that my Inverter would probably travel better, inside its packing box, than fixed to a wall/floor

Peter_n_Margaret · Guru

Tony Bev wrote:
Hi Stewart
I am not an electrician

I have a 300/600 watt (300 normal 600 peak), 12 volt DC to 240 volt AC Inverter

As I only use it to charge up my cordless drill, and cordless impact wrench batteries
(I have, just to make sure it can do so, charged my laptop, and phone, from this Inverter)
I just plug the Inverter into a ciggy type socket

The ciggy type socket, is connected direct to the house batteries, via a 10 amp fuse, at the battery

I keep the inverter, inside its original packing box, and packed away, in a cupboard, as I find that I seldom use it
I find that I can charge my laptop, phone, camera, rechargeable AA batteries, with the 12 volt ciggy socket system

My theory is, is that my Inverter would probably travel better, inside its packing box, than fixed to a wall/floor

A word of caution.

If you draw 300W from an inverter it will draw about 30A from the 12V system which is waaaaaay over the capacity of a cigarette lighter socket which is typically 10A.

Cheers,

Peter

Stewart · Senior Member

Hi Peter Good advice I did not know In future I will use a small lead and one appliance. Thanks Stew

Jaahn · Guru

Hi smile

A couple of comments ! I have found ciggy sockets are unsatisfactory for serious use, and you need good quality ones you can lockin the plug or it just works out. If you restrict them to just low currents they can be OK. BUT if they have a 10A fuse then that will limit them to 120W which is way less than 300W and indeed the startup current might blow the fuse turning it on. hmm

So hard wired close to the 12V battery will work best and if you need to move it a bit further then fit bigger heavier wires and some appropriate fuse for the max current and put it where you can access the switch easily.

As has been said an inverter produces 240V AC that will kill you just like at home, but it does not have any earth so not nearly as safe as at home if there is a faulty appliance! disbelief Remember that please. Double insulated items which are not fitted with an earth plug are safer. My advice is to just use a single shorter 240V lead to a convenient place for a single item to be plugged into.

Jaahn

I see there have been some posts while writing !

-- Edited by Jaahn on Thursday 16th of April 2020 01:41:24 PM

Tony Bev · Guru

Peter_n_Margaret wrote:
Tony Bev wrote:
Hi Stewart
I am not an electrician

I have a 300/600 watt (300 normal 600 peak), 12 volt DC to 240 volt AC Inverter

As I only use it to charge up my cordless drill, and cordless impact wrench batteries
(I have, just to make sure it can do so, charged my laptop, and phone, from this Inverter)
I just plug the Inverter into a ciggy type socket

The ciggy type socket, is connected direct to the house batteries, via a 10 amp fuse, at the battery

I keep the inverter, inside its original packing box, and packed away, in a cupboard, as I find that I seldom use it
I find that I can charge my laptop, phone, camera, rechargeable AA batteries, with the 12 volt ciggy socket system

My theory is, is that my Inverter would probably travel better, inside its packing box, than fixed to a wall/floor

A word of caution.
If you draw 300W from an inverter it will draw about 30A from the 12V system which is waaaaaay over the capacity of a cigarette lighter socket which is typically 10A.
Cheers,
Peter

Thanks for that info Peter, I appreciate it

And it is also good, that someone will come along, and show any reasons, why something should be done, in a particular way
In this case, hard wire verses a ciggy plug socket, on an inverter capable of 300/600 watts

Not sure how many watts are being used, to charge up my cordless drill and impact wrench, batteries
I placed my el-cheapo clamp meter, on one 12 volt wire going into the inverter, and it was showing (from memory), below 5 amps
This tells me (for my situation), I can safely use the ciggy plug, and not have to hard wire the inverter

The inverter I purchased (el-cheapo) from eBay) came with 3 cords
1 with a male giggy plug
1 with battery clamps
1 with lugs to be hard wired onto the battery

I am a little reluctant, to hard wire this inverter, in case the vibrations it will receive from travelling, damage the internals

Stewart · Senior Member

Thanks I really appreciate the advise. My inverter has very short leads close to the battery. So one appliance at a time in future. Stew

Peter_n_Margaret · Guru

One appliance at a time is certainly the only safe way unless the inverter is protected with an RVD.
The same applies to a generator, by the way.

I am not sure, but I also believe that power boards are not permitted in RVs. For one reason, they are not double pole switched which is a requirement.
Cheers,
Peter

Whenarewethere · Guru

Just a reminder plug a RCD in the 240 output of the inverter then plug your equipment into that. Don't want anybody being electrocuted for one reason or another!

Peter_n_Margaret · Guru

Whenarewethere wrote:
Just a reminder plug a RCD in the 240 output of the inverter then plug your equipment into that. Don't want anybody being electrocuted for one reason or another!

Sorry, but an RCD (Residual CURRENT Devise) will provide no protection for an inverter running more than one (non double earthed) appliance which (like a generator) is a floating supply without an effective earth.

For effective protection you need an RVD (Residual VOLTAGE Devise).

Cheers,

Peter

valiant81 · Guru

Hi all; I have had a pure sine wave inverter mounted under my bed and right next to the house battery and when i wanted to use the inverter, one would have to lift the bed and turn the inverter on at the built in switch. What i have now done is to install a small push on switch ( has a built in led to show it is in the "on" position. This switch controls a 12 volt 30 Amp relay and the relay switches the 12 volts to the inverter. No more lifting beds just to turn the inverter on or off. I only use the inverter for my electric shaver and the odd time when i need to use my laptop computer or charge the computer's battery.

Whenarewethere · Guru

Peter_n_Margaret wrote:
Whenarewethere wrote:
Just a reminder plug a RCD in the 240 output of the inverter then plug your equipment into that. Don't want anybody being electrocuted for one reason or another!
Sorry, but an RCD (Residual CURRENT Devise) will provide no protection for an inverter running more than one (non double earthed) appliance which (like a generator) is a floating supply without an effective earth.
For effective protection you need an RVD (Residual VOLTAGE Devise).
Cheers,
Peter

I see what you mean. My UPS being earthed, then in this situation a RCD works.

Stewart · Senior Member

Hi
So how to do people get on in the annex, when on a powered site

where i can have a power board and 2 appliances plugged in, a portable waeco fridge and maybe washing machine, or a cooker

Is this no good either, now im getting concerned

Thanks stew

Peter_n_Margaret · Guru

Stewart wrote:
Hi
So how to do people get on in the annex, when on a powered site

where i can have a power board and 2 appliances plugged in, a portable waeco fridge and maybe washing machine, or a cooker

Is this no good either, now im getting concerned

Thanks stew

I am not an electrician either Stew but my personal view is that what you suggest is probably reasonably safe, just not in accordance with all of the rules.

You do have protection via the RCD at the caravan inlet and that would be effective. You don't have double pole switching in the power board, but the power point that the power board is plugged into in the van is double pole.

Cheers,

Peter

Stewart · Senior Member

Thanks Peter a great help

erad · Guru

A RCD (residual Current Device) senses the current flowing into and out of an appliance, and if there is a difference of more than XX milliamps (from memory, 8 mA), the thing will trip because it will assume that there has been a leakage somewhere (probably via you). So, a RCD should protect you regardless of what is supplying the AC power.

Brenda and Alan · Guru

Erad that is not correct an RCD detects current flow to earth.

Alan

erad · Guru

My understanding or an RCD is that it senses the difference between Active and Neutral - the difference being earth leakage. An RCD device normally has no earth connection. The effect is the same.

Brenda and Alan · Guru

Erad I think you are correct . With a short through your body between active and neutral there is no difference in current so you are dead and the RCD won"t know. Hence an RVD is essential with inverters/generators plugged into your vans socket.

Alan

-- Edited by Brenda and Alan on Thursday 16th of April 2020 11:03:15 PM

KFT · Guru

G'day all

I am a licenced electrician with considerable experience in protection systems.

Erad you are entirely on the wrong track. Let me explain

An RCD does sense an imbalance in the Active/Neutral wiring but this imbalance can only occur if the fault current has somewhere to flow. This is what an earth connection does. The earth allows fault current to bypass the Core balance device and cause a trip when the imbalance reaches typically 30mA in domestic installations.

The issue here is that with an isolated supply such as a generator or an Inverter there is no earth reference. There is no Active/Neutral, only line 1/Line 2. With no earth connection there is no path for fault current to flow so no imbalance can be detected so an RCD will not trip.

An australian company designed and manufacture a new device called an RVD and this works on isolated supplies by sensing a voltage increase on the earthing conductor this then makes the RCD trip.

I hope I have written this in a way you can understand. If you still have trouble I am happy to explain further.

regards
Frank(KFT)

erad · Guru

Frank (KFT):
Thank you for your comment. I agree that if a person creates a fault between the high voltage (active) and low voltage (neutral), the RCD will not sense a fault and therefore will not trip. However, in nearly all cases the low voltage will not be very high (certainly not enough to be lethal). Certainly a fault could occur with a double insulated device when a person completes the circuit to the low voltage. But this would happen with a regular power supply anyway. If a person contacts a high voltage source and completes a circuit to earth (gets a shock), not all the current will return to the generator and therefore there will be a difference between the high and low voltage lines and the RCD should trip. What voltage does a RVD trip at?

-- Edited by erad on Friday 17th of April 2020 07:52:23 AM

-- Edited by erad on Friday 17th of April 2020 07:52:45 AM

Jaahn · Guru

Hi smile

Just a comment about the voltage of active and neutral. By design in our excellent house power distribution system, the neutral line is held to ground voltage by the link to ground at all meter boxes and transformers. That is the inbuilt safety of our power distribution system. So fair to say that the active voltage varies up and down from earth voltage (using one phase). aww

However an inverter (and generator) is a floating system and produces alternating voltage not linked to any earth (or neutral) to hold the voltages to normal limits. So there is no real neutral and active but just AC up and AC down, that voltage could be at any potential and probably drifts around up and down. That might give you some cause for thought about them and safety.

Jaahn

DMaxer · Guru

I remember when I first started off in my caravan that someone told me about inverters and their use when mains power was not available. I wandered off to an auto shop where the person there knew even less about them than I did. He sold me a 1000w inverter that had battery clips on the end of the leads. I asked him if I could use this in the 12 volt socket if I attached a lead with a socket plug on the end. "No worries" he assured me and off I went to charge up the laptop. I plugged the beast in to the socket and promptly blew the 10amp fuses to bits.

I called an auto electrician friend of mine who informed me that I was a complete idiot and that it should only ever be attached directly to the battery with the clips provided and that if it was to be attached to a socket, then that would have been provided. Well you live and learn and the inverter was then placed into a cupboard and has not been used since.

Undaunted by this minor mishap and after reading one of Chief Doug's enlightening posts, I went to a different place and purchased one of those small "coke can" type of inverter. This was plugged into the 12 volt socket and the lead attached to the computer whilst I stood well back waiting to see what disaster would unfold. Surprisingly, or at least to me, all went well. The battery hardly noticed the inverter bludging off it and the laptop kept charging as I was using it.

The moral of the story, less is best and listen to Chief Doug!

-- Edited by DMaxer on Friday 17th of April 2020 09:11:34 AM

Stewart · Senior Member

Hi Dimax what is the output of that one please sounds like a good idea thks Stew

Gundog · Guru

I have a very simple setup a manual changeover switch the load is Samsung 228ltr fridge, position 1 is 240v supply, position 2 is 350va Victron Inverter connected to a 120ah SLA battery which are located in the front boot.(this is a dedicated stand alone setup for the fridge only The current C/O switch switches both the active and neutral, the downside is when I switch to battery I have to go to the boot to turn on the inverter, the Victron has a facility to remote switch it on/off it would be great if I could get new C/O switch with an additional row to activate the inverter automatically.

DMaxer · Guru

Welcome to the forum Stewart. The inverter I purchased is about 150 watts from memory. It will charge the phone and the laptop easily. I turn the computer on and plug it into the inverter and can spend as much time as I like as it more than covers any drain on the battery. In fact, the battery is fully charged after about 30 mins even though I have been using the computer during all the charging time. The other good thing is that I can plug it into the cigarette lighter in the tug and charge up the laptop whilst driving along.

I haven't used it to operate anything else so don't really know what its limits are.

From memory it cost about $50 from an electrical store. It look like a coke can only smaller.

I hope that helps.

Stewart · Senior Member

Yes thanks I'll have look Cheers Stew

Warren-Pat_01 · Guru

I believe the amount of current to kill a person is 50mA. which not very much & I've had a number of close shaves at work & home. Luckily I have a high body resistance.

In the "good old days", Telstra & predecessors used powered coaxial fibre cable systems (carrying 960 channels of telephony, or TV). If a technician got across the feed, the constant current power supply sensed there was "another repeater" on the feed & wound up the current to match. Fortunately as far as I knew, no-one was killed on these systems.

Another thing to be wary of is that the cheaper inverters are modified sinewave type - they could damage a laptop. A good sinewave inverter is the safest to use on electronic equipment.