Mains Tester

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trevskoda said:
Just a thought,one of my houses has the earth rod under the stairs where it is dry,should i then connect a second earth wire to neg mains in to be sure. :unsure:
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The starting point for your decision is how did the DNO (power supply company, district network operator) supply the house ?
Was it TNS, TT or TN-C-S, etc
I guess its TT with a RCD but it really should be tested because you won't know how good the existing or the new rod (Z) will be, time to ask the experts.
 
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r4dent said:
View attachment 74672

This is based on Pascal's wager. An argument in presented by the French philosopher, mathematician and physicist, Blaise Pascal (1623–1662).
He used it to decide if Man should believe in God. (did I mention that I read "Maths & Philosophy" at University?)

The technique can also be used to evaluate decisions like whether to fit a corrective device for reversed polarity or not.
Clever because electricity wasn't discovered until over 100 years after he died.

Given that you can get a tester and a correction device for under £20, this is a no brainer for me.
You must make your own decision.
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Good to see you are being philosophically sound and staying alive :)
 
Fisherman said:
I was an electrician. Qualified 1976. I would never advise anyone to reverse polarity when connecting to AC mains. People have died due to reverse polarity wiring.
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More people have died due to faulty or No earth. More important to use a socket tester to prove the earth connection is good.

Alf
 
Fisherman said:
it’s vital that the positive is fused or protected with a residual current protector like an MCB (micro circuit breaker). If you reverse the polarity you have fused the negative, this means that the positive which will electrocute you remains connected if your MCB device switches or a fuse is blown due to low insulation (short circuit). Any metal surfaces that may not be earthed properly could then remain live after your safety fuse or MCB have actuated.
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Oh, where to start lol. If you want people to take your advice, you need to get the basics right.

It's live and neutral, not positive and negative.

MCB - miniature, not micro.

It is vital that the circuit is protected with a residual current device (RCD). An MCB will not provide this.

In a reverse polarity situation, with an appliance having a short live to earth, the MCB in the (now) neutral line won't trip. However, the one in the site power supply point will.

For reverse polarity to be an issue you need to have two things go wrong - no earth to the metal case of an appliance, and the appliance have an internal fault that means the case is connected to the mains.

And on top of that, to mean you are at risk of a dangerous shock, there needs to be no RCD present anywhere in the supply. There would normally be one in your van, and in the site power supply socket.

So it's a low risk. That said, is it worth checking the polarity? Yes, because it's easy and makes it even safer.
 
trevskoda said:
Very dangerous,pos wire is live neg is same as earth with no current,if you reverse live/neutral then the shell of a faulty unit like a toaster etc could give a nasty shock,remember only the live is switched and neg or eth is the frame,many folk get mixed up about ac current,ask any dead person.:eek:
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There is some confusion in your reply!

The Neutral conductor (a live conductor) should never be connected to the earth of the toaster, kettle, oven etc this is effectively p.m.e or T-N-C-S which should not be used ouside of the supply network, unless a T-N-S system. Assuming and RCD is fitted (and working) if the pos and neg of the supply to the appliance in your example is reversed and and the rest of the circuit is healthy (ie earth and neg seperate) the appliance will work fine. If the the neg and the earth were connected and the supply pos and neg are reversed then the RCD should trip immediately - indeed it should also trip if the pos and neg are correct due to earth leakage from the neg.
 
st3v3 said:
Oh, where to start lol. If you want people to take your advice, you need to get the basics right.

It's live and neutral, not positive and negative.

MCB - miniature, not micro.

It is vital that the circuit is protected with a residual current device (RCD). An MCB will not provide this.

In a reverse polarity situation, with an appliance having a short live to earth, the MCB in the (now) neutral line won't trip. However, the one in the site power supply point will.

For reverse polarity to be an issue you need to have two things go wrong - no earth to the metal case of an appliance, and the appliance have an internal fault that means the case is connected to the mains.

And on top of that, to mean you are at risk of a dangerous shock, there needs to be no RCD present anywhere in the supply. There would normally be one in your van, and in the site power supply socket.

So it's a low risk. That said, is it worth checking the polarity? Yes, because it's easy and makes it even safer.
Click to expand...

If my memory serves me correctly A point to remember from 16th edition IEE Regulations all MCB or Circuit breakers in motor caravans and caravans should be double pole MCB.
Alf
 
www.screwfix.com

LAP MS6860D 16A Socket Tester 230V AC

Order online at Screwfix.com. Pocket-sized, mains socket tester with LED indicators to show condition of circuit sockets. FREE next day delivery available, free collection in 5 minutes.
www.screwfix.com
£7.99. should be an essential tool for all campervans.

This cheap tool not only checks for reverse polarity, it also confirms that you have an earth. Plus several other checks.

It should be a no brainer
 
At last posting from somebody that understands reversed polarity. I will repeat my initial posting which was not understood .

In a healthy electrical circuit reversed polarity presents no dangers unless you wish to dabble inside the electrics whilst still connected to the EHU.
 
st3v3 said:
Oh, where to start lol. If you want people to take your advice, you need to get the basics right.

It's live and neutral, not positive and negative.

MCB - miniature, not micro.

It is vital that the circuit is protected with a residual current device (RCD). An MCB will not provide this.

In a reverse polarity situation, with an appliance having a short live to earth, the MCB in the (now) neutral line won't trip. However, the one in the site power supply point will.

For reverse polarity to be an issue you need to have two things go wrong - no earth to the metal case of an appliance, and the appliance have an internal fault that means the case is connected to the mains.

And on top of that, to mean you are at risk of a dangerous shock, there needs to be no RCD present anywhere in the supply. There would normally be one in your van, and in the site power supply socket.

So it's a low risk. That said, is it worth checking the polarity? Yes, because it's easy and makes it even safer.
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what’s your middle name pedantic.
if you want people to take your advice then try changing your attitude.
positive, negative, live and neutral I reckon we all know what was meant including you. Micro miniature you are having a laugh.
As for informing me that a metal surface that is not earthed is a hazard, thst was pointed out to me in 1976.
All I have tried to do is to ensure that folk on here don’t do as was advised yesterday and run with reversed polarity. But quite frankly after reading your post I wish I had not bothered.
 
Alf said:
More people have died due to faulty or No earth. More important to use a socket tester to prove the earth connection is good.

Alf
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of course it is more important I have never stated otherwise.
but the original post was about reverse polarity not earthing which is critical for safety. You have just liked a post stating that reverse polarity “poses no risk”
I am astounded that you think so.
 
In in

harrow said:
The starting point for your decision is how did the DNO (power supply company, district network operator) supply the house ?
Was it TNS, TT or TN-C-S, etc
I guess its TT with a RCD but it really should be tested because you won't know how good the existing or the new rod (Z) will be, time to ask the experts.
Click to expand...
It was tested when I finished the house and was ok,I will look at it again to be sure,many thanks
 
trevskoda said:
In in


It was tested when I finished the house and was ok,I will look at it again to be sure,many thanks
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I seem to remember our firm had to use bentonite or marconite or mat to get a good low Z earth reading. In not just a case of banging in a earth spike, it has to be tested.
 
Fisherman said:
of course it is more important I have never stated otherwise.
but the original post was about reverse polarity not earthing which is critical for safety. You have just liked a post stating that reverse polarity “poses no risk”
I am astounded that you think so.
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Read the post again if the installation is good and you don’t interfere or start to open equipment there is no danger.
In my youth When Current Operated Earth Leakage first came out a trick to prove their safety was to connect a trip up and prove it would work by holding live in one hand and touching earth with the other if all was ok you got a tingle before the trip worked and this was in the day of neutral operated earth loop testers.
 
I have a W4 mains tester permanently plugged into a socket in the van. When it shows anything other than the correct sequence of lights I fit my reverse polarity lead.

However I do not understand some of the sequences of lights. I don’t have an instruction sheet to explain the meanings. I really would be grateful if some of you ‘sparks’ could in a simple way explain what each means and what action is required to stay safe.


Thanks,

Davy
 
shortcircuit said:
In a healthy electrical circuit reversed polarity presents no dangers unless you wish to dabble inside the electrics whilst still connected to the EHU. Buy a tester but use it to ensure you have a good earth and forget about reversed polarity.
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What if a device plugged into your healthy circuit is defective?
 
TeamRienza said:
I have a W4 mains tester permanently plugged into a socket in the van. When it shows anything other than the correct sequence of lights I fit my reverse polarity lead.

However I do not understand some of the sequences of lights. I don’t have an instruction sheet to explain the meanings. I really would be grateful if some of you ‘sparks’ could in a simple way explain what each means and what action is required to stay safe.


Thanks,

Davy
Click to expand...

Just read the instructions for the led lights on the link you have given

Alf
 
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