Sub main protection!

[hoppy]

Hi,

been to job today to install a new bathroom light & fan in a HMO.

The 1st & 2nd floors are fed via a second db on the first floor - db2.

DB 2 is fed using 16mm twin, buried approx. 2m in wall, it is connected to the main tails next to db1 at the intake position, via Henley blocks, so single core insulation exposed (C2 as in kitchen cupboard used for plates etc). DB2 has 100A main switch and mcb's -no RCD protection. DB1 has a 63ARCCB Main switch.
Anyway not doing EICR yet, that is coming though.

My question is, when the EICR is completed it is going to fail due to the 16mm twin being protected by the 100 main fuse, so this will need rectifying, what would you do. Install an RCD unit which would mean a full test on DB2, or Is it ok to install a 2way enclosure with a 63A MCB, but would you still have to do a full test on DB2, or could you just test the sub main.
Not sure if it is acceptable to just protect the cable with an mcb, as I am not doing anyway work on the sub main.
The work I did in the bathroom is protected by a B6 60898, and I have installed an RCD FCU, to cover the light & fan!

Thanks!

 

[hoppy]

No takers on words of wisdom!!!!

 

[Plonker 3]

How old is the install? The regs are not retrospective so it may have been compliant at the time of install.

There is no "pass or fail" on a EICR. just satisfactory or unsatisfactory.

 

[Anthony S]

Hi,

been to job today to install a new bathroom light & fan in a HMO.

The 1st & 2nd floors are fed via a second db on the first floor - db2.

DB 2 is fed using 16mm twin, buried approx. 2m in wall, it is connected to the main tails next to db1 at the intake position, via Henley blocks, so single core insulation exposed (C2 as in kitchen cupboard used for plates etc). DB2 has 100A main switch and mcb's -no RCD protection. DB1 has a 63ARCCB Main switch.
Anyway not doing EICR yet, that is coming though.

My question is, when the EICR is completed it is going to fail due to the 16mm twin being protected by the 100 main fuse, so this will need rectifying, what would you do. Install an RCD unit which would mean a full test on DB2, or Is it ok to install a 2way enclosure with a 63A MCB, but would you still have to do a full test on DB2, or could you just test the sub main.
Not sure if it is acceptable to just protect the cable with an mcb, as I am not doing anyway work on the sub main.
The work I did in the bathroom is protected by a B6 60898, and I have installed an RCD FCU, to cover the light & fan!

Thanks!

To ask those kind of questions, it obvious to me your getting out of your depth. No dis-respect but the best thing you can do is hand the job back to where it came from.

 

[Guest125]

you have 2 options:

1) install a RCD at the supply end of DB2 as the cable is buried so if you alter the circuit you shouLd install RCD protection. The issue is here that a fault on the top floor would be inconvienient and maybe dangerous depending on the route to reset the RCD.

2). Install a new submain surface to allow for a OCPD to be installed and fused down to whatever sized cable you choose.

I would say that if you alter a distribution board supply cable you should test to ensure what you are turning on is in a satisfactory condition. So I personally would test all final circuits affected by your works.

 

[shanky887614]

install swa/conduit+singles whatever works out a better price so the supply doesn't need rcd.

you could always use surface trunking and singles if the budget is tight but swa wouldnt be too expensive.

£4.15 pm from tlc for 16mm 2c
£5.60 pm from tlc for 16mm 3c
£8.60 pm from tlc for 25mm 3c

 

[hoppy]

Dillb, it can't ever have been compliant, 16mm on a 100 amp fuse, and single insulated conductors open to touch!

anthony s, pointless reply, was after guidance as a bit of a grey area! We are not all super sparks! I learn every day!

 

[hoppy]

Shanky, new sub main is never going to happen as landlord won't want to spend out and damage house.

Looks like rcd upfront of db2 is best option!

 

[hoppy]

Shanky, new sub main is never going to happen as landlord won't want to spend out and damage house.

Looks like rcd upfront of db2 is best option!

 

[Guest125]

The RCD will need to be at the supply end not the DB2 end.

 

[Knobhead]

It’s quite simple, rip your work out because you’ve identified problems with the existing installation that affects your work.

Problems, I may add, you should have identified and pointed out first. It’s no good looking for excuses now, the deed is done.

 

[Darkwood]

Hoppy you are a Trainee Electrician ...you should have a competent person to watch over you, monitor your decisions and answer your questions...Why have you not asked them, you should not be doing this work unsupervised as a Trainee, if you are then this is why your possibly making costly mistakes here, learn your career and train the correct way, there are no shortcuts...

 

[Guest125]

The last two posts are what makes this forum great. EXTREMES!!

 

[Darkwood]

Looking at his join date I figure that his profile is now out of date so my last post may be misguided but if members dont keep their profiles to date then we will answer relative to what we find... its seems that too many trainees are now doing work and coming on here for answers... if you are a trainee then you cannot undertake any work unsupervised --- thus why ask us and not who's training you?

If he is fully qualified then I retract my comment and suggest he updates his profile.

 

[Anthony S]

Dillb, it can't ever have been compliant, 16mm on a 100 amp fuse, and single insulated conductors open to touch!

anthony s, pointless reply, was after guidance as a bit of a grey area! We are not all super sparks! I learn every day!

No such thing as a super spark, your either an Electrician or your not.

 

[andyelectric]

Hoppy, how are you certain that the main fuse supplying the 16mm t+e is 100A? Could be a 60 in there. And you say an EICR is coming. At whos insistence?

 

[hoppy]

I am not a trainee, I need to update my profile sorry!

Tony, harsh comment. I was passed the job as a favour to another spark, anyway basically a large room was split into 2 rooms, 1 being the new bathroom, which has no light as the existing light is in the other room. It has been like this for over a week, but the night before a student fell In the dark, so it was essential to get a light on (claim time).
I informed the landlord about the submain issues which he has agreed for rectification next week, once he has sorted a day out with all the tenants for the electric to be off!

I was simply asking for an opinion on whether the existing submain could be protected by a fuse of similar characteristics to the main fuse but lower rated,(and would this mean you take responsibility for testing all the circuits in DB2, even though nothing has really changed just the rating of the protective device) or if you think it would have to be RCD protected even though I am not altering the sub main!
I have never come across a sub main connected via Henley blocks and protected only by the main fuse! So bit of a grey area for me!

Andy, I don't know if the main fuse is 60A, as it is sealed an marked 100A and the supply tails are 25mm, and the dno never know what size fuses are in their cut outs!
So in my opinon safer to assume the worst case scenario!
The local council are asking for the EICR!

 

[Plonker 3]

So cutnthe seals and check what size fuse is fitted. As for RCD protection why not just put the henley blocks into a enclosure?

 

[hoppy]

haha, u know we cant cut seals!!!!!

As for the enclosure good idea. This is why this forum is good to get others opinions, sometimes the simplest things don't click in your head!

 

[Plonker 3]

haha, u know we cant cut seals!!!!!

Why not? Maybe the seals are not fitted anyway?