Is my electric contractor correct. Pics. Worried.

[JohnW2]

In that one case we do not open them above that load owing the the risk that any arc could contact earthed metalwork.

Interesting. You certainly wouldn't find me pulling a substantially loaded 60/80/100A fuse! Apart from anything else, even if I was well protected by PPE (and I've personally yet to see a DNO person use any significant PPE when pulling a domestic cutout fuse) isn't arcing likely to have an undesirable effect on the contacts of the fuse carrier and/or holder)?

Kind Regards, John

 

[westie101]

At LV if the operation is completed quickly, there is little risk of arc and subsequent damage.

Certainly all the equipment we use is rated for these operations

 

[JohnW2]

At LV if the operation is completed quickly, there is little risk of arc and subsequent damage. Certainly all the equipment we use is rated for these operations

Thanks. Again, all I can really say is 'Interesting'! If a substantial current is being broken, I would have thought that there there would almost inevitably be some arc, even if small and very-short lived - hence, I would have thought, a risk of some degree of contact damage - but perhaps I'm wrong!

Kind Regards, John

 

[westie101]

The realities of the different parts of the industry are quite a surprise, considering we all deal with the same product!

On the DNO side working live at LV on cables or lines is the norm,
No switches so fuses up to 630A can be removed underload. If needed supplies can be made dead or reconnected by cutting cables or overhead connections live.

Accidents are very few and far between and it is all legal!

Even getting to HV circuits up to 11kV, live working at those voltages is common, legal and safe.

But as often discussed there are few national rules so each DNO can decide on it's own ways of working as long as they comply with HSE law.
A huge difference to the domestic situation that seems, to me, mired in all sorts or rules, regulation and advice imposed by others on those doing the work.

 

[wv62]

But as often discussed there are few national rules so each DNO can decide on it's own ways of working as long as they comply with HSE law.

That is very true. I work on HV/EHV transformers mainly at power stations and sub stations and the differences in rules is staggering. Even simple things like inductions at sites varies from 1/2 hour to 6 hours. Best one so far was, ' Wear overalls, boot and hard hat. See that big grey box? If you climb on that you die!'

 

[RF Lighting]

I think the difference in rules and restrictions for your average electrician vs your average DNO worker all comes down to training (or lack of).

The DNO staff seem to be very well trained and truly understand what they are working with and the associated risks, so can be allowed to use their professional judgement within a set of guidelines to ensure things remain safe.

Unfortunately the average electrician lacks proper training or knowledge to make these judgement calls, so much stricter and prescriptive regulations need to be imposed to keep things safe.

We have a good gang of electricians and non electricians who regularly post on this forum, but it isn't representitive of your average electrician out there in the real world, many of whom can not even understand or follow (perhaps even have a knowledge of) the regulations governing our work, and I certainly wouldn't trust them to use their professional judgement to keep installations safe, as perfectly demonstrated at the beginning of this thread.

 

[ban-all-sheds]

This is from Aus, but something like these, this was trying to close onto a fault as well

https://www.youtube.com/watch?v=ATEWXsMawMg[/QUOTE]
I imagine that HV stuff behaves pretty much the same wherever it is...

More jolly videos here: http://www.capturedlightning.com/frames/longarc.htm

 

[ban-all-sheds]

13A does not mean anything, electrician talking from bumhole!

Disagree - I think it's quite reasonable for an electrician talking to a layman customer to use the term "13A socket".

I'd be very surprised though to find that the electric ovens part of a range cooker could be powered via one.

 

[PrenticeBoyofDerry]

My comments were taken from the contents of the OPs reply, indicating because it was a 13A socket that the oven was being fed from, that that would exclude the needs for RCD protection.
The fact it is 13A, does not exclude RCD protection.
If that is what the alleged electrician had indeed said?

 

[ban-all-sheds]

 

[Adam_151]

Unfortunately the average electrician lacks proper training or knowledge to make these judgement calls, so much stricter and prescriptive regulations need to be imposed to keep things safe.

I would say that towards the industrial end it gets a bit better, and some of the same issues that the supply industry have to deal with apply such as higher fault currents, pressure to keep the supply on, aged switchgear with very little in the way of intermediate barriers one the lid is off, hazards in the immediate vicinity such as traffic, industrial chemicals and processes, etc

Issues can occur when those who arnt aware of all the risks are involved, this chap: http://www.dailymail.co.uk/news/art...-apprentice-son-got-fatal-electric-shock.html appears to have sent an apprentice to get loop readings at high level lighting sockets. But forgot to draw his attention to the crane busbars and the apprentice probably wasn't aware that such things existed if he'd not worked in industrial before

 

[JohnW2]

I would say that towards the industrial end it gets a bit better, and some of the same issues that the supply industry have to deal with apply ....

I'm sure that must be true, since electricians who are "towards the industrial end" are really also "towards the supply industry end" - and clearly very different from those whose work/experience is entirely domestic/commercial (in relation to whom I imagine that RF's comments are probably very true).

Kind Regards, John

 

[EddieM]

I used to jokingly tell one of my apprentices that electricity flowed better when cables were neat. It was always jokey, but think he took it a little seriously. Now he's out on his own, he keeps saying to me "you weren't serious were you?".

Yep, them electrons prefer to travel in straight lines

If the frequency were a lot higher, I suppose you might have had a bit of a case!

Kind Regards, John

At the mind boggling rate of < 10^-3 m/s or less than 0.001 m/s or 0.002 MPH, and in terms of AC don't travel at all, not a lot of people know that!

 

[Essex1]

This question is impossible to answer without knowing the measured Ze.

Did the guy tell you what this was?

 

[JohnW2]

This question is impossible to answer without knowing the measured Ze. Did the guy tell you what this was?

Indeed - as was said in the very first reply:

That is a common method of earth connection. ... Unless it's defective (which can only be determined by testing), you do not need an earth rod.

However, even if the Ze is unacceptably high, I don't think that the OP should have to fit an earth rod himself. AIUI, although a DNO are not obliged to provide an earth, IF they do (which presumably is the case with this TN-S earth), then they are obliged to 'maintain' it in usable condition.

Kind Regards, John