Home DIY

Arcing, the kind that's caused by a loose connection which is basically what's happening if you sever a cable is an incredible process to visualise. The energy is basically consuming the metal that is conducting it. I suppose I'm just a bit fascinated by welding but that's basically a more controlled version of that explosion.

I would have thought that greater amperage would hold a greater risk by a margin but LV can kill you for sure and after that it doesn't really matter how much you were killed :)

I'm not sure about the breakers that would operate on LV outside of properties. Certainly inside a house you are at incredibly low risk of death with a working RCD but sticking a shovel in an LV main does sound like the kind of thing that could easily burn you alive. You do hear about people surviving it though. I've seen video of a builder hitting one with a breaker. There were 2 of them near it and they both suffered terrible injuries, survived but I'm not sure they are working again.

I'm only theoretically interested, I'm not offering to try it out.

This candian electrical engineer did a (imo pretty funny) video on how safe the UK domestic power supply infrastructure is.

https://youtu.be/abqMLqHwqpo

Arcing, the kind that's caused by a loose connection which is basically what's happening if you sever a cable is an incredible process to visualise.

This is why 18th has 'suggested' AFDD's now. The usual one it that IEE suggests you do this in current Regs. Then in the 19th Edition it'll become statuary.

Yes, been watching it coming over the hill! Apparently the available units are a bit clunky at the moment. I suppose there are a lot of big firms who install a huge amount of these before it filters down to the domestic market.

Arcing in Consumer Units is the main cause of electrical fire in the UK so it makes sense they're looking at it. I'm not sure if this is the prime reason for the recommendation.

New one's are single space units. So just straight replacement mcb or RCBO`s.

Same thing when RCBO's came in.

They will get more common place and cheaper as industrial and commercial will take the hit well before domestic.

He's very good.

I really like the RCBO's now they don't cost the earth. Takes no time to fit them and they are great for protection so I guess the AFDD will end up being about the same price once they are mandatory.

If you are going to plug in stuff while touching live components then you deserve every electrical shock you get.

really like the RCBO's now

Yeah. Less chance of nuisance tripping if each circuit is individually protected rather than split boards

Still better than when you had one single RCD for the entire system.

This is why main TT earthing RCD's are now time delayed.

The guy has a pretty sweet side gig out of giving himself electric shocks.

https://youtu.be/TwIvUbOhcKE

A mate of mine who is a highly qualified electrical engineer who designs stuff that he's not allowed to talk about for a major defense contractor told me that he's very good at putting complex concepts into terms that lay people can understand and that while what he does is stupid he knows how to make it safe. My mate really enjoys watching it too.

The guy has a pretty sweet side gig out of giving himself electric shocks.

Still an idiot though.

Preferred the first one, would agree he explains things well but the stunts are probably making the risk seem lower to younger viewers.

From electric to water.

Why would a water tank, used as water storage for hot water activate the overflow. There is an expansion vessel which has air in it. There is alot of limescale so was thinking maybe change the valve as the valve may not seat anymore due to limescale. Then re inflate the pressure vessel to see if it holds.

What would you do?

I have heard that the expansion vessels can fill up with water. Not much help I know but it's pretty much the sum total of knowledge in that area!

If the air pressure is too low, water pressure will partly/wholly fill much of the expansion vessel. Then any temperature increase and corresponding increase in volume may run out of space and lift the over pressure relief valve.

If the air pressure is too high, the expanding water lifts the relief before getting into the vessel.

Either one of these or older expansion vessels are prone to having the rubber diaphragm perish and fail which can turn it into a vessel. Mind you, if this happens they tend to leak.

If it's a pressurised expansion vessel then the diaphragm has likely failed. It's a closed system? No tank in the loft?

You'll need a new expansion Vessel, you can't replace any internal parts.

You can check the Schrader valve PSI if it has one and try to repressurise.

Domestic units don't generally have this though.

The diaphragm can fail, hence filling with water and no longer doing it's job.

@user69121 The expansion vessel has a Schrader valve that I pressed and air escaped and not water. The valve is at the bottom.

@Bobbo Yeah this is at least 10 years old so was thinking replace the vessel and the over flow valve, for peace of mind and hassle free hopefully.

@Mr_Sworld It does have a valve, all I have here is a track pump that is now broken. So new pump.

The expansion vessel has a Schrader valve that I pressed and air escaped and not water. The valve is at the bottom.

Sounds like the diaphragm is OK then, or you would have got water out.
How much air pressure is the important part.
With water pressure on, but heater switched off, run a hot tap for a few seconds to bleed off any over pressure.
Check the air pressure on the schrader valve. This will be the same as the water pressure/prv pressure on the other side of the diaphragm.
Switch off the water and run a hot tap. Repressurise the air to the same as the water pressure noted previously.

Turn on the water and heating again.
Any expansion above incoming pressure has maximum volume available before relieving.

Finished the shed window the other day. A few fuckups but it's only a shed, so there you go.

I put too much clear sealant on to hold the pane in, so it then affected the putty's adhesion. Applying the window putty was so much harder than the YouTube videos made it looked. Although after reading this afterwards I realised why:

http://www.idostuff.co.uk/sections/DIY/Window_Repairs/how-to-window-putty.html

Pro-amateur tip: empty all the linsead oil out into another container first.

To start my mix was more like cold marmite than playdoe. Unfortunately by the time I'd worked it out time was creeping on and the rain was coming, plus pressure to look after mini-H (I have no idea how parents manage anything).

I've tidied it up a bit since the photo and started cleaning the glass up.

A few things learnt and theres still the other window to fix - although not urgently as this was the only one at imminent risk of taking mini-H's head off.

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Anyone want an ‘urban, edgy, reclaimed workshop table top’ before I cut it in half an bin it? 2440x1220x25, can be cut down, collection from Hackney Road.

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That'll buff out

Fill/flood with resin, add hairpin legs, sell for mega bucks as aforementioned urban edgy chic.