EICR Observations

[yellowvanman]

Would like to get other opinions on the following observations of a property that was rewired 10 years ago:

1) Excessively long ring - r1/rn/r2 = 1.56/1.56/2.48

2) Mismatch of RCBO - Hager RCBO in Legrand CFU with othe rLegrand MCBs

 

[Leesparkykent]

Would like to get other opinions on the following observations of a property that was rewired 10 years ago:

1) Excessively long ring - r1/rn/r2 = 1.56/1.56/2.48

2) Mismatch of RCBO - Hager RCBO in Legrand CFU with othe rLegrand MCBs

What's the Zs?

 

[yellowvanman]

Zs is OK, 1.14ohms.- anyway got a rcd.

The issue would be volt drop - this was brought up once on one of my assessments!

 

[kingeri]

If the circuit is for general sockets in a house, and lightly loaded, I wouldn't be massively concerned about volt drop. Not great design though!

 

[Andy78]

Why would you be verifying voltage drop on an EICR ? It is not within the general remit or requirements of the regs regarding periodic inspection.
This would be near impossible to do accurately anyway as you would have no idea of the exact length of concealed cables. Backwards working of the resistance values would not be an accurate way to verify the length of the cable in my opinion.

 

[bigspark17]

I wouldnt be overly concerned with the volt drop and as @kingeri said its poor design but its within zs advantage of ring circuits, have the customers experienced any volt drop related problems.? As for diferent brand of switchgear you could c3 as per manufacturers instructions not followed, but if they all fit soundly with no evidence of damage i wouldnt even mention it, just my opinion.

 

[Leesparkykent]

Okay mV/A/m for 2.5mm T&E is 18. If you take the design current as 26A for the RFC (20A at the mid point and the rest evenly distributed to the rating of the OCPD. maximum recommended value of volt drop 11.5V(5%).

18x26x98.3/1000/4= 11.5V.

An r1 value of 1.56 with 2.5 would indicate a ring final circuit length of 214 meters 1.56/0.00728=214

18x26x214/1000/4=25V

section 525 is relevant. If 25Volts volt drop is going to cause a potential danger that impairs the safe functioning of equipment then code 2 IMO. If it doesn't then code 3.

If the RCBO fits perfectly no code and just a comment if its not fitting perfectly then code 3. Code 2 if causing any stress on busbar etc.

 

[yellowvanman]

Re ring length.

I refer to Table 7.1(i) OSG - max length of 32A B type - 106meters.

Loading is not heavy so in practise volt drop shouldn't be an issue, but needs mentioning as far as I'm concerned.

Thanks for comments

 

[ETO]

I would note it on the observations sheet but not code it personally. So long as zs is fine. When I QS test sheets I like seeing that the electrician has put some extra thought into the installation assessment. Rather than seeing blank sections all the time. Pet hate of mine.
C3 the mismatched mcbs.

 

[westward10]

Definitely C3 noncompatible device whether it fits correctly or not.

 

[Risteard]

Definitely C3 noncompatible device whether it fits correctly or not.

Depending how poor the fit it could easily make it a C2 (or perhaps a C1 if they have butchered around it to the point where there are now exposed live parts - although this is likely to be recorded separately from the incorrect protective device which has been fitted).