Departures from bs7671, certification.

[odawire]

Hi, I have always made sure my installs have no departures from bs7671 but I'm doing a ccu change next week and have done some preliminary testing and the heating circuit (boiler and heating controls) has low IR readings, had a look in all obvious places and cant find any problems, had trouble breaking the circuit up as its a bit messy, client has just decorated so he doesn't want any damage to the house, seeing as its all fixed equipment (I'm unsure on the cable routes but id guess its buried less than 50mm at some point) is it acceptable to leave this circuit unprotected and note it on the departures section? all the earthing/bonding is mustard. Any experience on this would be appreciated, thanks.

 

[telectrix]

firstly, what was the IR reading for the heating circuit? secondly, the cable buried <50mm deep -- if it's going to be RCD protected, then no problem. don't forget that the IR would need to be under 10KΩ to cause RCD tripping.

 

[odawire]

Hi, should have explained, I have a rig I made up I use sometimes, its basically an rcd adaptor that I wire into and plug into a socket, when I did this it tripped, the IR reading was bouncing around I think it settled around 7Mohms across all points, I remember it was the exact same number. The reason Im asking is, I want to know if its acceptable to leave it off the RCD side if I have to, as I don't think I can leave them with no heating at this time of year, can I note it as a departure as the cable is probably less than 50mm deep

 

[telectrix]

at 7MΩ, i wouldn't worry. BS7671 quotes 2MΩ as a minimum, so just RCD protect the circuit.better still, fit a RCBO in the non RCD section of the CU.

 

[odawire]

thanks for your response but im not worried about the circuit, when I put it on an rcd it was tripping straight way, so I don't want to RCD protect it, I want to put it on an MCB with no rcd protection.

 

[telectrix]

then there's a fault on either the circuit or the heasting system. does it still trip with the boiler out of circuit?

 

[Guitarist]

Personally, I wouldn't just put it on a non-protected side due to a fault. Tell the owner that it will need to be sorted before the CU can be changed.

 

[Richard Burns]

Just as a reminder departures from BS7671 are only cases where the circuit is not designed to BS7671 but is still safely designed, it is not a non compliant situation, which is what you are describing (circuit requiring RCD protection not RCD protected because of a fault on the circuit).

That said if you are changing a CU you only need to ensure that the circuits you are reconnecting are safe for continued use (which may well be dubious in this case) not that they meet current regulations.
I would do as Guitarist says, tell them they need that fault rectified before changing the CU.

 

[DPG]

thanks for your response but im not worried about the circuit, when I put it on an rcd it was tripping straight way, so I don't want to RCD protect it, I want to put it on an MCB with no rcd protection.

So...Would you sleep soundly at night knowing that you had connected this known-faulty circuit to the non-RCD side so that the fault wouldn't show up? Daz

 

[GLENNSPARK]

Hi, I have always made sure my installs have no departures from bs7671 but I'm doing a ccu change next week and have done some preliminary testing and the heating circuit (boiler and heating controls) has low IR readings, had a look in all obvious places and cant find any problems, had trouble breaking the circuit up as its a bit messy, client has just decorated so he doesn't want any damage to the house, seeing as its all fixed equipment (I'm unsure on the cable routes but id guess its buried less than 50mm at some point) is it acceptable to leave this circuit unprotected and note it on the departures section? all the earthing/bonding is mustard. Any experience on this would be appreciated, thanks.

what do you want?...a round of applause?
i had this down as standard...