Armored cable ...

[Risteard]

Not a whole lot of explanation there though really is there. I think you're the one who doesn't know what you're doing. You don't seem to be able to comment on any technical aspect of this project whatsoever other than a load of old pony about metals and that the world will end when I plug my iPhone in to charge. Happy to be wrong but nothing to convince me in your sour rants so far.

I do know what I'm doing and I am quite capable of discussing technical aspects of your project.

Also the risk of dissimilar metals is not "a load of old pony" and indeed the Wiring Regulations require you to avoid that.

I will not entertain helping an incompetent danger like you to carry out your dangerous work, however.

 

[Risteard]

Indeed.

And I realise that you will go to considerable lengths to avoid answering questions when you find the answers uncomfortable.

With reference to the galvanic table, please explain the relative difference between the corrosion which occurs with copper/galvanised steel vs brass/galvanised steel.

Just accept that it is one of your unknown unknowns @ban-all-sheds - qualified Electricians know not to do it. You have learnt something new today.

 

[oldbutnotdead]

OP- if you were to peruse Part P of the Approved Documents you would find that installing or modifying external sockets and/or installing supplies to outbuildings is notifiable work. It also requires a certain amount of testing to ensure it is safe (using test instruments that are a bit pricey to buy or even hire for a one-off, when you add the notification fee you'll quickly find it is way cheaper to get an electrician to do those bits)

Bodging the SWA sheath into a terminal block is just that- a bodge. Gland it off properly- Pirahna earth nuts are much easier than standard gland nuts.

Good call using 1 core of the (hopefully) 3 core SWA as CPC- the armour does perform adequately if properly terminated and protected from the weather but that performance can degrade significantly and rapidly if the (steel) armour starts to corrode. Or if the armour isn't properly terminated (see above).

Did you check volt drop/CCC for that cable length and gauge?- all very well you saying it'll only have a phone charger plugged in, wonder what will happen when someone has the bright idea of plugging a heater in for those long hot summer nights?

What colour is the inner sheath of the core you've used for earth? (lots of 3 core SWA is 3 phase so black, brown, grey). If it isn't green/yellow then you have to sleeve it. The phase conductors- if they aren't blue and brown then sleeve them as well.

How deep is the cable buried? What mechanical protection is in the trench above the cable? Have you used marker tape? Have you staked the trench path (so you know where the cable is and more importantly in the future someone else will know where the cable is)

Your lighting cable- problem with having the RCD at the gazebo end is the cable running through the garden is not protected. So when you stick a pickaxe through it you'd better hope that Zs is low enough to trip the overcurrent device before you soak up a lethal current.

Bottom line- there's a lot more to the job than chucking a random bit of cable up the garden.

 

[EFLImpudence]

OP- if you were to peruse Part P of the Approved Documents you would find that installing or modifying external sockets and/or installing supplies to outbuildings is notifiable work.

That is only true if it is a new circuit.

Outside power and lighting is no longer notifiable in England (but still is in Wales)

To save wading through Approved Documents, it is much quicker and easier to look at the actual law.
http://www.legislation.gov.uk/uksi/2012/3119/regulation/6/made

 

[ban-all-sheds]

Just accept that it is one of your unknown unknowns @ban-all-sheds - qualified Electricians know not to do it. You have learnt something new today.

OK - I don't expect that anybody will be surprised to see that your desire to avoid embarrassment by refusing to answer a question is always going to be your only concern.

So I'll stop asking you, and instead tell you the truth, based on actual facts.

For normal environments, such as storage in warehouses or non-temperature and humidity controlled environments, there should not be more than 0.25 V difference in the anodic index. For controlled environments, in which temperature and humidity are controlled, 0.50 V can be tolerated. For harsh environments, such as outdoors, high humidity, and salt environments, there should be not more than 0.15 V difference in the anodic index.

The difference between copper and galvanised steel is 0.85 and between brass and galvanised steel it is 0.8.

So yes, copper is marginally worse, but both are high.

You are ignoring the fact that a copper conductor is also captive within that terminal.

It is not a significant fact.

If corrosion between copper and armour is a concern, then so, at less than 6% difference will be corrosion between brass and armour. And vice-versa if there's no or little concern about the contact between armour and gland.

What difference does that make?

The answer to that, Risteard, is "virtually none".

Copper and steel in the same terminal will react with each other. I already pointed this out.

And so, Risteard, will brass and steel, to almost the same extent.

Ah, I thought the objection was steel armour in brass terminal.

The only people who would not object to that but would object to copper and steel in contact are those who have not managed to think about the fact that there is very little difference between the two scenarios.

I realise that you are not an Electrician @ban-all-sheds but every Apprentice-trained Electrician knows of the dangers of combining dissimilar metals. Indeed they will have been taught this as part of their theory.

The brass of a SWA gland and the armour it clamps are dissimilar metals combined.

Shall we all just take it as read that you will never be willing or able to explain why you are concerned about the corrosion risk when armour comes into contact with copper but not when it contacts brass?


You got it wrong, Risteard, and your evasion has not concealed that.

 

[securespark]

Is the gland not made of the same material as an earth terminal?

I was about to post: The armour and the gland are dissimilar metals too.
EDIT: But everyone else got there before me...

I should give myself 1000 lines:

I must read the whole thread before posting.

 

[Risteard]

OK - I don't expect that anybody will be surprised to see that your desire to avoid embarrassment by refusing to answer a question is always going to be your only concern.

So I'll stop asking you, and instead tell you the truth, based on actual facts.

For normal environments, such as storage in warehouses or non-temperature and humidity controlled environments, there should not be more than 0.25 V difference in the anodic index. For controlled environments, in which temperature and humidity are controlled, 0.50 V can be tolerated. For harsh environments, such as outdoors, high humidity, and salt environments, there should be not more than 0.15 V difference in the anodic index.

The difference between copper and galvanised steel is 0.85 and between brass and galvanised steel it is 0.8.

So yes, copper is marginally worse, but both are high.



It is not a significant fact.

If corrosion between copper and armour is a concern, then so, at less than 6% difference will be corrosion between brass and armour. And vice-versa if there's no or little concern about the contact between armour and gland.



The answer to that, Risteard, is "virtually none".



And so, Risteard, will brass and steel, to almost the same extent.



The only people who would not object to that but would object to copper and steel in contact are those who have not managed to think about the fact that there is very little difference between the two scenarios.



The brass of a SWA gland and the armour it clamps are dissimilar metals combined.

Shall we all just take it as read that you will never be willing or able to explain why you are concerned about the corrosion risk when armour comes into contact with copper but not when it contacts brass?


You got it wrong, Risteard, and your evasion has not concealed that.

I didn't get it wrong. I don't feel the need to answer a fruitcake like you though. In the south of Ireland when we use copper Earthing conductors with galvanised Earth electrodes we cover the connection with Denso tape as required by the Wiring Rules. It brevet dawned on you about the dissimilar metals because you remain a fruity DIY weirdo.

 

[securespark]

Risteard

The thing is: it has dawned on Ban that there is an issue about dissimilar metals; your stumbling block is that you cannot see the marked similarity between brass and copper. It does not matter whether it is brass in contact with steel or copper in contact with steel, both combinations are dissimilar metals.

Are you implying that brass SWA glands do not comply with regulations as that would mean bringing dissimilar metals together?

Denso tape? This stuff?
https://www.amazon.co.uk/All-Trade-...=2025&creative=165953&creativeASIN=B00904QH0Y

What effect does covering a joint between two dissimilar metals with tape have on that joint? Does it prevent any reaction? Does 7671 demand tape be wrapped around SWA glands?

Regardless of the type of brass, copper is the largest component in the mix, followed by zinc. Lead is sometimes added to make the metal more malleable and small quantities of manganese and nickel can be added to alter the colour of the metal. Arsenic and aluminium can also be added to improve workability and corrosion resistance.

I fear you will not care, but I held you in high regard until now.

Instead of explaining why you think it is acceptable to have steel and brass in contact with each other but not steel and copper, you have robustly defended your decision to the point of proceeding to question the mental state of a poster that disagrees with your explanation.

Throwing insults is often the behaviour of someone who has lost, or feels he is losing, an argument.

You have learnt something new today.

As one of my colleagues used to say, "Every day is a school day".
You never stop learning something new.
The danger comes when you believe you know everything and argue with everyone who disagrees with you.

 

[Perleman10]

Bodging the SWA sheath into a terminal block is just that- a bodge. Gland it off properly- Pirahna earth nuts are much easier than standard gland nuts.
>> Didn't realise it was a bodge at the time but do now & will rectify & that is what this thread is for as I realised it wasn't correct

Good call using 1 core of the (hopefully) 3 core SWA as CPC- the armour does perform adequately if properly terminated and protected from the weather but that performance can degrade significantly and rapidly if the (steel) armour starts to corrode. Or if the armour isn't properly terminated (see above).
>> Yes it's 3 core

Did you check volt drop/CCC for that cable length and gauge?- all very well you saying it'll only have a phone charger plugged in, wonder what will happen when someone has the bright idea of plugging a heater in for those long hot summer nights?
>> It's good for 4KW. This is our forever home.

What colour is the inner sheath of the core you've used for earth? (lots of 3 core SWA is 3 phase so black, brown, grey). If it isn't green/yellow then you have to sleeve it. The phase conductors- if they aren't blue and brown then sleeve them as well.
>> I will sleeve them all as you suggest

How deep is the cable buried? What mechanical protection is in the trench above the cable? Have you used marker tape? Have you staked the trench path (so you know where the cable is and more importantly in the future someone else will know where the cable is)
>> It is under the patio and then goes straight up the leg of the gazebo so there is no area where it could be disturbed

Your lighting cable- problem with having the RCD at the gazebo end is the cable running through the garden is not protected. So when you stick a pickaxe through it you'd better hope that Zs is low enough to trip the overcurrent device before you soak up a lethal current.
>> So maybe I should move the external RCD to the side of the house where power first exits the house then

Bottom line- there's a lot more to the job than chucking a random bit of cable up the garden.

>> yes I can see that but nothing you have mentioned can't be remedied easily. I have a spark coming tomorrow and will discuss either remedying it or certifying my remedial work

 

[Taylortwocities]

https://www.screwfix.com/c/electrical-lighting/cable-accessories/cat830484

What's the difference between the internal / external ones as they all seem to be ip66 rated
Or the difference between 20 & 20S on this page please?

Also what's the name of the item / can anyone link to the item I need to attach to the hole of the collar (as per pic below) inside the junction box please? On the videos I have seen on Youtube they drill the junction box to put the screw through is that the same for the socket end of the cable too?

Hello Perleman. I thought that I could be helpful, rather than join in with the general banter and slagging off.
As you are determined to do this yourself, here's a very helpful video on how to terminate SWA properly.

 

[winston1]

Hi thanks for your help, it is as follows:
The house's main consumer unit is RCD protected for mains power
Then inside the lounge on the wall there is one of these connected to the mains:

13A 30MA DOUBLE POLE PASSIVE RCD CONNECTION UNIT

Well you don't need that second RCD then. Two RCDs in line on the same circuit is pointless. It just means you have two to reset after a fault.

 

[Perleman10]

Well you don't need that second RCD then. Two RCDs in line on the same circuit is pointless. It just means you have two to reset after a fault.

It was like that when we moved in, it's right on the other side of the house from the CU and is the socket the previous occupier used for the mower & garden tools

 

[Risteard]

Denso is a petrolatum tape and does indeed help to prevent corrosion. Its use was not being discussed in relation to BS7671 but ET101. You cannot get past the fact that Apprentice-trained Electricians know not to combine the armour of an SWA cable into a block connector with copper conductors. The issue with dissimilar metals is a real one, and doesn't alter the fact that several strands (or even all of them - which wasn't the case here) are not to be used as conductors in that manner. It was an abhorrent way to connect the SWA cable and should and must be repudiated.

As for ban-all-sheds or Kevin or whatever you want to call him, he's not even worth ignoring.

 

[Perleman10]

Looking at these gland kits, what is the difference between 20 and 20S and internal / external (all the internal ones seem to be have the same IP rating as the external ones)

 

[Perleman10]

It was an abhorrent way to connect the SWA cable and should and must be repudiated.
As for ban-all-sheds or Kevin or whatever you want to call him, he's not even worth ignoring.

What's abhorrent is your attitude. I recognised that it wasn't done right & am seeking help to remedy it.
This is a DIY forum, which stands for 'Do It Yourself', you obviously have a problem with this & don't want to provide help / support to others & just throw your weight around & sidetrack the discussion. I would suggest you find another discussion / forum that may be more receptive / appreciative to your approach. Or just get a life.