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Help with Periodic Coding


OldPeeBee

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OldPeeBee

I have just finished a PIR on an extended bungalow with a stable block - was rewired when the extension was built (3 years ago) but the work wasn't notified. Owner wants a certificate, so the builder has asked me to do a PIR for the installation.

Generally, most things are testing OK; however, I could do with some comments on coding for the following:

1. Main earth to a MET block in 16mm; earths to 3x distribution boards in 10mm; water bonding in 16mm!

2. DB4 is in the stable block (built of wood on concrete base; water supply present but in plastic pipe throughout) and is fed from a 40A MCB in DB3 via 10mm 3core SWA - armour has been split into two bundles, taped with green/yellow tape and inserted into DB3 earth rail. At DB4 end this has not been done. Supply is TNC-S. Zdb at DB4 is 0.83.

3. Rcd test at DB4 trips the RCD at DB3. I am thinking of changing the RCD at DB3 for a plain main switch as DB3 has circuits for a cooker - no socket; water heater and the stable block.

The builder is anxious not to upset the owner with an unsatisfactory report and I haven't completed the paperwork yet. If he gets me to rectify the faults, would I be OK to then issue a satisfactory report or should I produce an unsatisfactory one and then certify the repairs separately?

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NozSpark
I have just finished a PIR on an extended bungalow with a stable block - was rewired when the extension was built (3 years ago) but the work wasn't notified. Owner wants a certificate, so the builder has asked me to do a PIR for the installation.

Generally, most things are testing OK; however, I could do with some comments on coding for the following:

1. Main earth to a MET block in 16mm; earths to 3x distribution boards in 10mm What size are the L & N, how long are they and are they fused??; water bonding in 16mm! No problem

2. DB4 is in the stable block (built of wood on concrete base; water supply present but in plastic pipe throughout) and is fed from a 40A MCB in DB3 via 10mm 3core SWA - armour has been split into two bundles, taped with green/yellow tape and inserted into DB3 earth rail. Code 2 - incorrect method of termination At DB4 end this has not been done. Supply is TNC-S. Zdb at DB4 is 0.83.Code 2 - still needs a gland

3. Rcd test at DB4 trips the RCD at DB3. I am thinking of changing the RCD at DB3 for a plain main switch as DB3 has circuits for a cooker - no socket; water heater and the stable block. No discrimination of RCDs - code 4--- circuits still need RCD protection under 17th ed Code 1 -- Stables should not be fed from a TNC-S supply!!

The builder is anxious not to upset the owner with an unsatisfactory report and I haven't completed the paperwork yet. If he gets me to rectify the faults, would I be OK to then issue a satisfactory report or should I produce an unsatisfactory one and then certify the repairs separately?

Yes, I'd give the builder an unsatisfactory PIR and a quote/estimate for the repairs; then certify the repairs as necessary

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OldPeeBee

Tails are 25mm to Henley block and 25mm to all 3 DBs in the house.

How do I achieve discrimination of RCDs if both require 30mA protection?

Am I correct in thinking that the SWA needs glanding at the house end but not at the stable and that the earth core needs connecting at the house but not at the stable and that I should install an earth rod for the stable?

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NozSpark
Tails are 25mm to Henley block and 25mm Tails??to all 3 DBs in the house.

How do I achieve discrimination of RCDs if both require 30mA protection?

Am I correct in thinking that the SWA needs glanding at the house end but not at the stable and that the earth core needs connecting at the house but not at the stable and that I should install an earth rod for the stable? You should terminate the SWA in an enclosure before the CU as IIRC you are not allowed 2 different earthing systems within the same enclosure

Mine in RED

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OldPeeBee

Sorry, maybe some confusion in my terminology. L&N tails from supply fuse to Henly blocks in 25mm; from there to each DB in 25mm. Main earth in 16mm to an earth block (tend to call them MET block incorrectly); from there to each DB in 10mm.

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Andy™

main earth should not be less than half the size of th neutral, so 25mm

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NozSpark

Is there any chance you can draw a picture of this installation with lengths, sizes and types of mains cables??

Are DB1, 2 & 3 in the same location??

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SPECIAL LOCATION
The builder is anxious not to upset the owner with an unsatisfactory report and I haven't completed the paperwork yet. If he gets me to rectify the faults, would I be OK to then issue a satisfactory report or should I produce an unsatisfactory one and then certify the repairs separately?

Hello oldpeebee, one quick observation......

IMHO The builder is NOT anxious not to upset the owner,

because if he was he would have sorted all proper notification out in the first place...

The builder would appear to be out to do stuff as cheap as possible....

because to be honest if he had used a proper notification & certification path in the first place... you would not be there doing a PIR!?

Just make sure all your investigation & reporting are all above board and correct and you can justify any observations with any relevant regulations to back up your observations...

Personally I would always approach work like this with the assumption that I am not going to get any follow up work. And use it as if it were an approved contractor scheme assessing your performance...

Cross all the "t"ees, dot all your "i"s sleep easy in your bed then if or when you do get the follow up work you can justify your costs fully without having to cut corners.

(90%+ of the time you do get the followup work anyway if you do a proper job that can be backed up by regs etc..!)

;)

The Best practice guides have good info for PIR codes..

Patch will find a link in a bit!:D

SL.

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OldPeeBee

3. Rcd test at DB4 trips the RCD at DB3. I am thinking of changing the RCD at DB3 for a plain main switch as DB3 has circuits for a cooker - no socket; water heater and the stable block.

The DB is in a cupboard next to another cupboard with the water heater in - cable surface clipped, not buried ; the cooker is on the other side of an internal wall with switch/outlet in kitchen cupboard - cable surface clipped, not buried; stable feed is SWA underground. None of these need RCD protection even under 17th, do they?

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NozSpark

If the switch/outlet incorporates a socket then it will ned RCD protection under the 17th,, however if the socket is not needed then you could just put a cooker switch instead and you wouldn't need RCD, otherwise you could put the cooker on an RCBO!

The problem is, does the supply to DB3 need RCD protection???

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OldPeeBee
The problem is, does the supply to DB3 need RCD protection???

No, the DB supply is via 25mm tails surface mounted.

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