UK DIY Shocker!!!

[DIYer Gaz]

Hi guys,

I hope everyone is well.

So to detail my experience, I had a loose wire behind my electric cooker mains plug, so I tested the plug after sorting the wire forgot to turn off the mains at the box and yes as you can guess as I went to push the socket into the wall to screw in, two fingers on eight hand touches the metal box behind the socket all whilst being barefoot standing on the kitchen floor. Never felt anything like it, straight up my eight arm fuzzy head and all that. This was late last night about 10.30pm. Should I be worried? It is fair to say I will be staying away from electrics from now on.

 

[pc1966]

Thanks for the info, I will give the test button a push! It has tripped in the past when we have had the oven and the 4 rings on the hob on. So I assumed it was working. But I have not tested it recently.

They can trip for two very different reasons:

• Overload
• Leakage

Both are possible reasons with a cooker/oven circuit.

If it tripped due to all loads being on it suggests the circuit is not adequate for the cooker. It is unusual to see only 16A for that, but not exceptional (my own flat, for example, has a 32A circuit which is more traditional, though the oven only takes 13A or so max). Do you know the rating of the appliance? Or the make & model to look it up?

Also oven heating elements have a tendency to absorb moisture so can be leaky if not used for some time. That can trip the RCD side, but usually after reset and heating up they dry out internally and all is well for ages.

 

[radiohead]

That's interesting can you explain why?

Whilst labouring as a kid I was on the third rung of a step ladder and chasing a horizontal chase in a travel agency.

I'd have been 15-16 at the time and most of the details are those I was told as my recollection is very limited.

Anyway, one minute I'm chasing away the next I'm ten feet away, on my arse, covered in travel brochures, bleeding from my head with (bizarrely the only thing I vividly remember) a cracking view up the skirt of the travel agent lass who had come over to help.

I was told I had gone through a "415V armoured".

I saw the bolster that had a two pence sized semicircular chunk missing.

The lass in the travel agent said there was a flash and bang and I "flew backward and up, hitting the shelves on the wall (10ft)behind me"

Their was blood and hair on the top shelf, which was highr than I was initially working.

It may be possible I jumped backwards and up??

Would like to know why being thrown is not a possibility though.

In the case of a non fatal electric shock contact with live parts must be very brief or it would be fatal, in your case you must have jumped away violently, a natural reaction. Fatal electric shocks usually occur when the victims muscles contract causing a hand to tighten onto the contact and being unable to release.
The energy required to physically hurl a person through the air would be considerable, in effect being in contact with an explosion, and undoubtedly fatal.
It's very common for people to tell me their story of getting a shock and they invariably claim to have been 'thrown across the room', it's standard procedure to dramatize the tale. Sorry, but if they had been they would be dead.

 

[DIYer Gaz]

They can trip for two very different reasons:

• Overload
• Leakage

Both are possible reasons with a cooker/oven circuit.

If it tripped due to all loads being on it suggests the circuit is not adequate for the cooker. It is unusual to see only 16A for that, but not exceptional (my own flat, for example, has a 32A circuit which is more traditional, though the oven only takes 13A or so max). Do you know the rating of the appliance? Or the make & model to look it up?

Also oven heating elements have a tendency to absorb moisture so can be leaky if not used for some time. That can trip the RCD side, but usually after reset and heating up they dry out internally and all is well for ages.

Hello, I just tested the trip button and the power did trip to the cooker. So an after thought given the further information. Would the circuit trip if by some chance I managed to touch the neutral and livewire at the same time?

 

[pc1966]

Hello, I just tested the trip button and the power did trip to the cooker. So an after thought given the further information. Would the circuit trip if by some chance I managed to touch the neutral and livewire at the same time?

No, if you were unlucky enough to touch live and neutral (instead of earth) it would simply see you as a "normal load". It only notices if the current going out of the live wire is not balanced by the same current returning on the neutral (to within the 30mA trip level).

That is the most common sort of danger, for example, if there is a fault and you touch a live wire (or metal case that has become live) while also touching earth (actual ground, or something connected to it like a water pipe or radiator, etc).

It is unusual to get a L-N shock unless poking inside stuff, which is not uncommon on this forum!

Hopefully you also tested the other RCBO trip buttons? They are more complex than a MCB so it is really a good idea to check periodically.

 

[DIYer Gaz]

They can trip for two very different reasons:

• Overload
• Leakage

Both are possible reasons with a cooker/oven circuit.

If it tripped due to all loads being on it suggests the circuit is not adequate for the cooker. It is unusual to see only 16A for that, but not exceptional (my own flat, for example, has a 32A circuit which is more traditional, though the oven only takes 13A or so max). Do you know the rating of the appliance? Or the make & model to look it up?

Also oven heating elements have a tendency to absorb moisture so can be leaky if not used for some time. That can trip the RCD side, but usually after reset and heating up they dry out internally and all is well for ages.

The oven is a Diplomat Select 620 electric oven, it has a power supply of 230v - 50hz, power max usage is 4.07kW and fuse rating is 20amp. There is a separate electric hob too.
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No, if you were unlucky enough to touch live and neutral (instead of earth) it would simply see you as a "normal load". It only notices if the current going out of the live wire is not balanced by the same current returning on the neutral (to within the 30mA trip level).

That is the most common sort of danger, for example, if there is a fault and you touch a live wire (or metal case that has become live) while also touching earth (actual ground, or something connected to it like a water pipe or radiator, etc).

It is unusual to get a L-N shock unless poking inside stuff, which is not uncommon on this forum!

Hopefully you also tested the other RCBO trip buttons? They are more complex than a MCB so it is really a good idea to check periodically.

So for me to have received the shock I did, I must have just touched the live wire? However, would it be safe to say the current did not exceed the 30mA if the trip switch did not activate? I just don't understand why it never tripped if it is working. Would footwear, ring on opposite hand etc, have a bearing on the circuit not tripping?

 

[ipf]

So for me to have received the shock I did, I must have just touched the live wire? However, would it be safe to say the current did not exceed the 30mA if the trip switch did not activate? I just don't understand why it never tripped if it is working. Would footwear, ring on opposite hand etc, have a bearing on the circuit not tripping?
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There could be something amiss with the RCD. It would be as well to recall your electrician and ask for him to test for operation times and to carry out a ramp test to find out at what current level the unit operates.

 

[DIYer Gaz]

So for me to have received the shock I did, I must have just touched the live wire? However, would it be safe to say the current did not exceed the 30mA if the trip switch did not activate? I just don't understand why it never tripped if it is working. Would footwear, ring on opposite hand etc, have a bearing on the circuit not tripping?

There could be something amiss with the RCD. It would be as well to recall your electrician and ask for him to test for operation times and to carry out a ramp test to find out at what current level the unit operates.
[/QUOTE]
Thank you for the advice. When you say unit are you referring to the RCBO unit? If so, is it possible for this unit to trip at a higher level than the 30mA stated on it?

 

[ipf]

Thank you for the advice. When you say unit are you referring to the RCBO unit? If so, is it possible for this unit to trip at a higher level than the 30mA stated on it?
[/QUOTE]
Yes the RCBO. It is possible for a FAULTY unit to trip at a higher level but 30mA is the safety 'cut off point', to make it sound simple, to comply with regulations. It is manufactured to operate below 30mA.

 

[telectrix]

Gaz, if you post your location i'm sure one of us could pop round and do a simple test on your RCBOs.

 

[pc1966]

The oven is a Diplomat Select 620 electric oven, it has a power supply of 230v - 50hz, power max usage is 4.07kW and fuse rating is 20amp. There is a separate electric hob too.

Based on your photo of the CU you have a 16A RCBO on the cooker circuit, but the oven is 18A and if you have a hob as well adding to that demand then it would explain it tripping with everything on!

However, would it be safe to say the current did not exceed the 30mA if the trip switch did not activate? I just don't understand why it never tripped if it is working. Would footwear, ring on opposite hand etc, have a bearing on the circuit not tripping?

As already said by @telectrix and @ipf the RCBO might be faulty and so a proper test using an electricians Multi Function Tester (MFT) would be a good idea even if the self-test button is firing it.

If there is someone on here not far from your location that could take a look you would be well advised to take them up on it. They could also take a quick look at the cable and arrangement for the cooker as 16A is quite low and it makes me wonder if the wrong RCBO was used, or if the circuit was previously intended for something lower in power.
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Thinking about it, if someone had managed to earth the cooker circuit to neutral alone (TN-C style) then the RCBO would not trip on a live to "earth" fault. Difficult to imagine that being done, monumentally stupid to do so, but not completely beyond possibility?

 

[DIYer Gaz]

Based on your photo of the CU you have a 16A RCBO on the cooker circuit, but the oven is 18A and if you have a hob as well adding to that demand then it would explain it tripping with everything on!


As already said by @telectrix and @ipf the RCBO might be faulty and so a proper test using an electricians Multi Function Tester (MFT) would be a good idea even if the self-test button is firing it.

If there is someone on here not far from your location that could take a look you would be well advised to take them up on it. They could also take a quick look at the cable and arrangement for the cooker as 16A is quite low and it makes me wonder if the wrong RCBO was used, or if the circuit was previously intended for something lower in power.
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Thinking about it, if someone had managed to earth the cooker circuit to neutral alone (TN-C style) then the RCBO would not trip on a live to "earth" fault. Difficult to imagine that being done, monumentally stupid to do so, but not completely beyond possibility?

Thank you for the info. I have asked a friend to come round, he is a qualified electrician but I appreciate the offers you are all great people! So would you think the amperage was at a level to hopefully not cause any lasting damage? The doctors have just told me that home electrics would not be enough to do lasting damage, however I feel differently given the information you have all provided. There is a red and black wire in the left side of the wall socket (as you look at it) and there yellow green wires in the top right of it.

 

[telectrix]

The doctors have just told me that home electrics would not be enough to do lasting damage,

"Home" electrics are just the same as any other electrics. a safe voltage is considered to be 50V A.C. you have 240 volts. you only have to see reports of homeowners being killed , messing about with their electrical equipment. Several headline cases have been reported, notably the woman who was killed after the relative had fitted a spoon rack and drilled into a cable. She had her leg in contact with the casing of the dishwasher (earthed) when she went to grab a spoon.

 

[DIYer Gaz]

The doctors have just told me that home electrics would not be enough to do lasting damage,
"Home" electrics are just the same as any other electrics. a safe voltage is considered to be 50V A.C. you have 240 volts. you only have to see reports of homeowners being killed , messing about with their electrical equipment. Several headline cases have been reported, notably the woman who was killed after the relative had fitted a spoon rack and drilled into a cable. She had her leg in contact with the casing of the dishwasher (earthed) when she went to grab a spoon.

Omg I had not heard that story. That is horrific. He was saying home electrics should not be enough to cause lasting damage. So I suppose they reckon if you are lucky to survive the initial shock and everything else is fine following checks then there should be no onset issues. However, like you said 240v I suppose that could easily do some lasting damage.

 

[pc1966]

Death is as lasting damage as you get

The lowest voltage known to have killed someone is 42V, but generally 50V is considered safe - if it is not a wet or otherwise high-risk environment (e.g. operating theatre, etc). The USA works mostly on 110V as the final circuit but still sees around 150 deaths per year from electricity related accidents (not all from shock, a significant number are burn injuries).

You should never be complacent as no one wants to see another preventable statistic.