Landlords EICR and t&e sub mains without RCD

[vitoboy]

Hi All

Been doing a lot of EICR for landlords recently due to new legislation and agents i guess.
One common issue im finding even with relatively new (10 years) old installations is a T&E sub main.
Now some of these have a 100mA rcd .. or no RCD .. some are even wired in concentric cable.?..

My issue is that if they have no RCD we cant fit one because then we are putting the whole install on a single rcd which is no longer allowed and apart from that unwelcome by tenants when they need to go down stairs in the dark to find a RCD to reset every they plug in something rubbish.

So im left upgrading the submains to SWA ..as they should have been in the first place .. (they are typically buried in the wall and we cant prove they are more than 50mm deep) .
But in a few cases upgrading to SWA is a total nightmare if not impossible without destroying lots of the building to get them in.
Just wondering your thoughts on this and how you've been dealing with similar situations..or if you have any suggestions.
cheers
vitio

 

[Koipin]

100ma RCD on the Sub-main, Dual 30mA RCD on the Consumer unit in the Flat. No need for SWA I'd say.

 

[vitoboy]

could you indulge me on your thoughts for that .. i was under the impression that its a domestic premises and any unprotected cable less than 50mm deep or in a wall with metal parts needed RCD protection via 30mA RCD..?

 

[Andy78]

What code are you issuing for buried twin and earth cables ?

 

[vitoboy]

What code are you issuing for buried twin and earth cables ?

2 potentially dangerous..

 

[Andy78]

2 potentially dangerous..

And then the landlord gets you to do remedials which include adding RCD protection for every circuit ? Can't be a bad thing.
Myself I code that particular instance a C3 in line with industry guidance.

 

[westward10]

It is a bad thing now because how do you resolve it. I'm with Andy I can't see that as a C2 issue.

 

[vitoboy]

And then the landlord gets you to do remedials which include adding RCD protection for every circuit ? Can't be a bad thing.
Myself I code that particular instance a C3 in line with industry guidance.

Not being funny at all .. but can anyone explain to me how this is not potentially dangerous. .. adding in this particular case that's it's a tt system. .
But I would say it's potentially dangerous if it was tncs or tns

 

[westward10]

Now you mention TT so the biggest issue is fault protection if no rcd is in place.

 

[vitoboy]

Yep.. it's really a requirement here..
But some persons I know have suggested that I do a eicr starting at the consumer unit in the flat and ignore the sub main..? as is external..
But really I'm not happy with this.

 

[Andy78]

Not being funny at all .. but can anyone explain to me how this is not potentially dangerous. .. adding in this particular case that's it's a tt system. .
But I would say it's potentially dangerous if it was tncs or tns

Avoiding the need for fault protection via RCD for TT for now, a different issue, the hazard that exists with buried cables only occurs when destruction of the wall and electrical installation occurs. If that is a defining parameter then a socket may be worthy of a C2 in case you hit it with a sledgehammer.

 

[Wilko]

Hi - for TT I’d use a 100mA S type (time delayed) RCD up front for fault protection. The time delay is normally sufficient to allow the regular RCDs / RCBOs to trip for any final circuit faults.

 

[Nigel]

100ma RCD on the Sub-main, Dual 30mA RCD on the Consumer unit in the Flat. No need for SWA I'd say.

That won’t comply. Cables buried in walls need to have 30mA additional protection.

 

[Nigel]

2 potentially dangerous..

C3 would be more appropriate.

 

[Nigel]

Not being funny at all .. but can anyone explain to me how this is not potentially dangerous. .. adding in this particular case that's it's a tt system. .
But I would say it's potentially dangerous if it was tncs or tns

You are the one C2ing it. You tell us what the potential danger is of cables in a wall with no RCD additional protection.

 

[Wilko]

That won’t comply. Cables buried in walls need to have 30mA additional protection.

Oops, I forgot this was also a problem to be solved. If they’ve put the unprotected sub main in a wall less than 50mm then my 100mA S type is no good .

 

[Nigel]

Personally I think the cost to install SWA or surface cabling is too high when compared to the safety improvement. If I was the landlord I would not bother installing additional RCD protection for cables in walls in these properties and ensure S Type 100mA RCDs were installed for all sub-distribution circuits on TT supplies.

 

[Charlie_]

Are the consumer units plastic?

 

[vitoboy]

Oops, I forgot this was also a problem to be solved. If they’ve put the unprotected sub main in a wall less than 50mm then my 100mA S type is no good .

Well yes

 

[vitoboy]

Eerr
You can see a socket ....
You can't see a buried cable..
You can screw into the live then lick the screw ... if your that way inclined..
No operation of any protective device..
Is this not the point..?

 

[richy3333]

C3 all the way. No way a C2

 

[vitoboy]

C3 all the way. No way a C2

Why..?

 

[Andy78]

Eerr
You can see a socket ....
You can't see a buried cable..
You can screw into the live then lick the screw ... if your that way inclined..
No operation of any protective device..
Is this not the point..?

It's sort of the point, if your point was that you cannot possibly protect against every random eventuality and so coding should be realistic based on normal use of the installation. But I don't think that was your intended point, just what I inferred from that.

 

[vitoboy]

It's sort of the point, if your point was that you cannot possibly protect against every random eventuality and so coding should be realistic based on normal use of the installation. But I don't think that was your intended point, just what I inferred from that.

Why do we fit RCDs for stuff buried in a wall less than 50mm deep if not to guard against things that aren't "normal use"??

 

[richy3333]

Why..?

Because if I am the inspector I am suitably competent, qualified and experienced enough to judge a T&E ‘sub main’ as was described in the original OP as a C3

 

[Andy78]

Why do we fit RCDs for stuff buried in a wall less than 50mm deep if not to guard against things that aren't "normal use"??

For additional protection. Not basic or fault protection.

 

[Wilko]

To me, the “cables in walls” reg came as a safety improvement, but not having it wouldn’t automatically mean the installation was unsafe.

 

[vitoboy]

Because if I am the inspector I am suitably competent, qualified and experienced enough to judge a T&E ‘sub main’ as was described in the original OP as a C3

Ok I accept that point of view.
This is why Im Posting this .. because I value the feedback here.
At this time I'm not completely sure i agree completely.
The thing that worries me is just that we have the current regs for a reason .. this goes against them.
I need to be happy with what I'm doing .. so I seek consensus...not just cost cutting for landlords.
I thank you for your points.

 

[vitoboy]

For additional protection. Not basic or fault protection.

For me right now .
Both.
But I'm willing to be persuaded otherwise .. but I'm not yet.

 

[vitoboy]

For me right now .
Both.
But I'm willing to be persuaded otherwise .. but I'm not yet.

With tt anyhow
With tncs or tns yes its additional... but it's still a requirement really unless someone can show me something that says different.

 

[Nigel]

For me right now .
Both.
But I'm willing to be persuaded otherwise .. but I'm not yet.

If you need RCDs for basic protection you are in a whole world of trouble and cables in walls is the least of your worries.

 

[mattg4321]

Do you know that the T&E is buried at a depth of less than 50mm?

Maybe you can see that it is, or maybe you're guessing?

I had a similar situation recently. As far as I could see it looked like the cable was always over 50mm deep in the wall, but I couldn't inspect the whole run.

I didn't code it, but listed it in the limitations. You'd hope that the people who installed it 5 years ago would've done it properly...

 

[Nigel]

With tt anyhow
With tncs or tns yes its additional... but it's still a requirement really unless someone can show me something that says different.

It is a requirement. So is brown sleeving on black cables that are live. Does not make it potentially dangerous if it is missing though does it.

 

[vitoboy]

If you need RCDs for basic protection you are in a whole world of trouble and cables in walls is the least of your worries.

Accepted.
Fault

 

[Charlie_]

Is the buried at less than 50mm rule still apply to cables within the prescribed zones?

 

[Wilko]

Is the buried at less than 50mm rule still apply to cables within the prescribed zones?

Yes sir

 

[Andy78]

For me right now .
Both.
But I'm willing to be persuaded otherwise .. but I'm not yet.

Yes in the case of TT then it's different. Like I said my argument is solely for buried twin and earth cables less than 50mm deep.

 

[Wilko]

Just thinking out loud - if the TT was PME’d then at least the sub-main would have fault protection. I did a job recently where SSE had just been through and upgraded the o/h and were able to provide PME.

 

[Charlie_]

Yes sir

10 points to Griffendor!

 

[SparkyAndGeorge]

Would there be much point putting a 100ma RCD upfront of one of these sub mains as it still wouldnt meet the 30ma requirement?

 

[James]

Would there be much point putting a 100ma RCD upfront of one of these sub mains as it still wouldnt meet the 30ma requirement?

in my opinion it would be worth it, especially if it was me that had just put a nail through the cable.

 

[SparkyAndGeorge]

in my opinion it would be worth it, especially if it was me that had just put a nail through the cable.

But both scenarios would warrant a C3 code?

 

[Charlie_]

But both scenarios would warrant a C3 code?

C1 if James’ nail is still sticking out of the cable

 

[James]

C1 if James’ nail is still sticking out of the cable

I always pull them back out again,
quick bit of polyfiller and nobody would know.?

 

[westward10]

Would there be much point putting a 100ma RCD upfront of one of these sub mains as it still wouldnt meet the 30ma requirement?

It is a TT earthing system a 100ma device will provide fault protection.

 

[Mapj1]

For TT surely there must be some kind of RCD up front, as changing to SWA would be worse than useless - a nail connecting to a live wire and to a high Z earth that just makes the building live but trips nothing is worse than a nail on its own that is just live.
If you can beef up the thin bit of wall to 50mm, or maybe make the route un-hidden in some way (metal detector and some labels/paint ? ) then a 100mA or 300mA up front would be my preferred But a long run of any cable on TT without an upfront RCD is asking for trouble, even a few m of meter tail in plastic trunking feels icky.

 

[Bobster]

For TT surely there must be some kind of RCD up front, as changing to SWA would be worse than useless - a nail connecting to a live wire and to a high Z earth that just makes the building live but trips nothing is worse than a nail on its own that is just live.
If you can beef up the thin bit of wall to 50mm, or maybe make the route un-hidden in some way (metal detector and some labels/paint ? ) then a 100mA or 300mA up front would be my preferred But a long run of any cable on TT without an upfront RCD is asking for trouble, even a few m of meter tail in plastic trunking feels icky.

An upfront RCD is not a must, although in most TT situations tt is highly likely. Especially in domestic situations where it is not only needed for fault protection due to low Zs.

I've done a few installations where the Ra is sufficient not to require them.