Can Your Installation Rely on a TT Earth Electrode

Рет қаралды 11,496

Күн бұрын

UK electrician Matt walks you through the mains end of a TT earthing arrangement that has had a very poor looking earth electrode for the past 15 years. Up until Matt investigated the old gas pipe that was being used at the earth electrode and was corroded as it entered the ground. So under normal installation condition the old earth electrode and the metallic incoming gas and water pipes were providing a very good connection to earth. The problem on this site is the earth electrode was an old gas pipe rotten at the point it entered the ground so if the incoming gas and water were upgraded to plastic the installation could have little or no connection to earth. To improve the installation Matt could install a new earth electrode but he has decided to upgrade the installation to PME. In this video we take a look at the new consumer unit with a type 2 SPD and RCBO's.
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== 🕐 Time Stamps - Cut to the action 🕕 ==
00:00 - Consumer unit change
00:26 - Pre test results
00:53 - MCBs ready for SWA cables
01:13 - Ready for extra circuits
01:37 - MET
02:18 - Service head upgrade
02:57 - Earth electrode
04:25 - Is it Instagram ready Matt
05:27 - Fault finding
06:35 - 3mm sleeving
Videos are training aids for City and Guilds (C and G) and EAL courses Level 1, 2, 3 plus AM2, AM2S and AM2E.
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Пікірлер: 34

@mb-electricalservices 11 ай бұрын

Nice job bud. Lots of forward thinking too which is excellent!! As far as the neatness is concerned, I used to beat myself up quite a lot as I was comparing my work in consumer units to the Instagram crowd. There's nothing wrong with the neatness at all! You have a method that works well and I take my hat off to you. Mike.

@brianlopez8855 7 ай бұрын

Neat use of the ever universal steel washers !

@Dog-whisperer7494 11 ай бұрын

Excellent job Matt . And the CU looks good to me.👍 Great video as always

@philipoakley5498 5 ай бұрын

+1 for the fault finding aspects!! (Just moved into a new old house with overhead supply, still with original fusing and no clear earthing )

@kevlark 3 ай бұрын

At 3:23 I can spot what looks like an old Yaesu FR50B Receiver. I'm a sad collector of radio equipment.

@Doopyy 10 ай бұрын

I always say that over doing the board with tie wraps is bad practice, now the next guy has to put his side cutters near potentially live parts to locate cables for faults as you said. tells me that people that do that never fault find.

@detroutspinners9933 11 ай бұрын

So even though they don’t have a main earth, the builder is safe using his cement mixer because the bonding is giving you a sufficient earth fault loop path?

@paulmatthews5470 11 ай бұрын

Essentially, yes. My house water main comes in for the first 6” in copper before it turns to plastic. Without the bond in my Ze is 17.8ohm (TT) and connected is 0.26ohm. As it is all plastic now it’s not connected and I couldn’t get to it now if I tried. The regs have a roundabout way of allowing the use of a mains service as an earth rod as long as it is privately owned and not likely to be removed or altered. I’ve seen it done in old mansions where the water board takes their supply to the boundary then connects to a private section of the mains that takes it onwards. Just need to make sure no one digs it up though. I recall better information being in GN8.

@travoltasbiplane1551 11 ай бұрын

If you're a cowboy

@leighsmith7965 10 ай бұрын

To carry out your fault current on a TT system you should measure between live and neutral, that will give you a true KA reading

@rosskeeley9946 11 ай бұрын

Neat and tidy job, nowt wrong with that. 👍🏼

@GSHElectrical 11 ай бұрын

Thanks 👍

@chas3997 11 ай бұрын

You could have used boot lace ferrules for the RCBO leads it stops the copper getting damaged over time 😀

@GSHElectrical 11 ай бұрын

They come sonic welded 👍🏻. However I do love a ferrule 😀

@konstantine381 11 ай бұрын

Our cement mixer doesn't even have an earth 😂

@IAmThe_RA 11 ай бұрын

Would you conduct earth resistivity test? If yes, please show us.. Thanks.

@lewishumphries2893 11 ай бұрын

I'm not in the industry but he has a result for the resistance of the external earth Ze , also mentioned results of insulation resistance and looks like results for rcbo trip times and continuity of cpc . I'm sure plenty of other pro guys could comment further

@IAmThe_RA 11 ай бұрын

@@lewishumphries2893 Earth resistivity test is needed to determine how long the earth electrode should be or how many of them needed. Unlike many European countries (and possibly the North America as well), British regs don't require an electrode for a TNCS system. So British electricians in general are not experienced in conducting earth resistivity test. That's why I am curious to see.

@JohnDundee-el2ro 3 ай бұрын

Better these 2 cpcs and the main earth behind the neutrals

@phill3144 11 ай бұрын

Is the red and black wiring from older cabling? I thought I would have to be renewed for regs

@sam.p12345 11 ай бұрын

Why do you think that? The only relevant regulation prescribed by the building regs is that the installation is reasonably safe. Old colour wiring is reasonably safe.

@intercity125 11 ай бұрын

Not at all. And you don't even need the "wiring colours to different versions of BS7671" sticker anymore in domestic if the notice is with the EIC.

@ciaranhughes8705 11 ай бұрын

On a job yesterday and the supply to their garage was a swa cable that consisted of a 6mm brown 6 x1mm blue with 6mm earth. So neutral is connected via 6, 1mm cables. I have never seen this cable before. Anyone here know if this is safe. The load should be shared but it's bizzare. I don't want to have to change the cable it's it's safe and sits correct with the regs but I can't find where it's stated otherwise. Cheers to anyone that replies

@yngndrw. 11 ай бұрын

No idea with regards to the regs, but that's a concentric cable as used by the DNO.

@leeroots3527 8 ай бұрын

Sounds like a split concentric cable. A nice cable to use for sub mains that are not buried underground or in the fabric of the building for example, but as far as BS7671 is concerned, in the same position as T&E or any other unprotected cable. Not a replacement for SWA.

@thomasdalton1508 4 ай бұрын

One thing to note here is they aren't 6mm and 1mm cables, they are 6mm^2 and 1mm^2 cables. Those figures are cross sectional areas, not diameters. If they were diameters, that wouldn't work. 6 cables with 1/6 the diameter doesn't give you the same current carrying capability. You would need 36 cables. That shouldn't be a problem because cables are always labelled with cross sectional area and that is what you should always be using, but I can imagine a DIYer that doesn't know that measuring the cable they are removing with calipers and realising it is twice the size of the cable they have so running two cables thinking it is equivalent when they actually need four cables (or to go and buy the proper cable!). I would suggest always being precise and writing mm^2 and saying square millimetres just in case anyone ever does get confused.

@JohnDundee-el2ro 4 ай бұрын

Your consumer unit would have looked a lot better if you had all your neutral tails at the front of the main earth the 2 cpc and the 2 reds and blacks just at the neutral bar side of the consumer unit the rest is ok