That’s more than enough to boil a kettle.

Well 16a at 230V would boil a kettle or two, but of course there is not 230V behind it - if one was very brave and interrupted that earth path (and this is a 'thought experiment' only do not try it) then the open circuit voltage would almost certainly not be 230V, unless there is an open circuit in the street main, but more like a few volts to perhaps 10V or so.

What is happening is that there is a few hundred amps RMS flowing in the street neutral, and that has a resistance of some tens of milliohms, and adding another few tens to hundreds of milliohms in parallel takes a measurable percentage of it, in the usual  resistors in parallel sort of way. That can still be enough current, even at a few volts, to cause some serious heating if connections are a bit rough.

The whole thing only becomes a really serious hazard when the official neutral path is faulty and most or all of the neutral current is sent via the plumbing etc. That is the situation when anyone plumbing and getting themselves in the current path, perhaps when replacing the stopcock, may receive a lethal shock,

The other scary part of course is that removing the building main fuse(s) and switching off all loads has little to no effect, as the current is coming in from elsewhere.

Mike

I'd be surprised if there were hundreds of amps flowing in the street neutral - I'd expect the phases to roughly balance out along the street and the neutral to carry just the residual imbalance, unless by unhappy chance every third household along the street decided to  boil a kettle.

So for a service cable PEN fault, I'd expect one house's full N current to be diverted along pipes into a few neighbour's bonding cables, while for a street cable open PEN I'd expect just the residual N of the further half of the street to appear.

I wouldn't expect parallel N currents to reach 16A without an open PEN. But I could be wrong!

An interesting question would be what to do for the arcing gas pipe connector shown in that video (apart from calling 105)? Disconnect the gas bond at the MET (using goggles and gloves and treating everything as live)? Something else? Nothing?

well it is possible that it is your own load contributing, and if there is an open PEN then the supply voltage may be about go off piste, so turning off whatever can safely be is a good idea.

Turning off the gas tap - perhaps with gloved hands, is another good idea. Then go outside to wait for the DNO who can pull something at the substation that will quieten things down.

Err OK perhaps 'hundreds of amps' is a bit hyperbolic on my side, so my apologies for that, but 16A diversion is in the range that may well  be not an actual fault. It is all about the relative resistance of the mains and the parallel path, and that is not always that favorable, especially when street piping is quite chunky.  And a neutral  imbalance current of perhaps a hundred amps or so is credible at certain times at least on a larger TX (half megwatt and up )and will of course depend  on local use patterns time of day etc.

M

well it is possible that it is your own load contributing, and if there is an open PEN then the supply voltage may be about go off piste, so turning off whatever can safely be is a good idea.

Turning off the gas tap - perhaps with gloved hands, is another good idea. Then go outside to wait for the DNO who can pull something at the substation that will quieten things down.

Err OK perhaps 'hundreds of amps' is a bit hyperbolic on my side, so my apologies for that, but 16A diversion is in the range that may well  be not an actual fault. It is all about the relative resistance of the mains and the parallel path, and that is not always that favorable, especially when street piping is quite chunky.  And a neutral  imbalance current of perhaps a hundred amps or so is credible at certain times at least on a larger TX (half megwatt and up )and will of course depend  on local use patterns time of day etc.

M