Square D Consumer Unit

[richchad]

I two old Square D Quickline consumer unit, one is fitted with a 100amp 30ma RCCB and controls all the 13amp power, cooker etc.

The second one just for lighting only has a switch, no RCCB.

I understand to comply with later regs this should have an RCCB, my question is I can buy an old RCCB on Ebay, I have seen some 100amp 30ma RCCBs and some 100amp 100ma RCCBs.

I am not sure what the exact difference is, I assume the 30ma will trip quicker than the 100ma?

Do the later regs state what the m/amp rate should be?

 

[Adam_151]

Is there a reason you want to install RCD protection to the lighting DB? There is little reason to strive to acheieve compliance with the latest revision unless other work is being done on the installation; if your install is correctly installed to the 16th then there is no issue and if its not, you'd be better addressing that

 

[ricicle]

For what purpose do you need to change the arrangement ?

 

[richchad]

Yes there is work going to be done to the bathroom lighting, it was mentioned earlier when I had some work done in the kitchen but as circuits were on the ring main CU, it wasn't necessary to change the lighting one.

 

[sherlockholmes]

Just out of interest, what's the difference between an RCCB and an RCD?

 

[ricicle]

Why don't you let your electrician sort it out for you ?

 

[richchad]

Because the electrician wanted to replace the complete CU, and I can replace just the RCCB before he does any work.

 

[ricicle]

Because the electrician wanted to replace the complete CU, and I can replace just the RCCB before he does any work.

Is he willing to let you do that ?

 

[EFLImpudence]

Just out of interest, what's the difference between an RCCB and an RCD?

An RCCB is an RCD but not all RCDs are RCCBs.
An RCBO is an RCD but not all RCDs are RCBOs.

RCD is a generic term for these kinds of devices.

 

[flameport]

While you could buy some old RCD on eBay, there are some things to be aware of:

- What you are buying could be damaged, broken, counterfeit or simply not suitable for your particular consumer unit.
- Fitting the RCD will require that the supply to the consumer unit is isolated properly.
- The new RCD will need to be tested using test equipment you almost certainly do not have.
- If there are faults on the existing circuits connected to the CU, it is likely that you won't be able to switch the new RCD on, and you will therefore have no lighting until the fault(s) are located and repaired.
- Alterations to a consumer unit are notifiable work, therefore by doing this you will be breaking the law. (you obviously won't be notifying this yourself, as the cost of doing so would probably be greater than having a new CU installed).

 

[RF Lighting]

I can't see how installing an up front RCD even just for the lighting CU will leave the installation compliant with regulation 314.1 (i)

 

[richchad]

Okay guys, I hear what you are all saying, and will probably leave it as it is, but can anyone answer my original question regarding using a 30ma or 100ma RCCB?

 

[echoes]

A 30mA RCD will trip when there is an imbalance of >30mA in the line and neutral currents.

A 100mA RCD will trip when there is an imbalance of >100mA in the line and neutral currents.

Which one will trip first for leakage below 100mA is a no-brainer. For leakage current above 100mA it depends on the trip characterists of the devices i.e. the speed at which the device will trip. If they are nominally equivalent, then it's unpredictable.

It was common for TT installations to be protected by a slow-operating 100mA RCD to provide discrimination between RCDs. But now all domestic circuits requiring RCD protection must be at 30mA.

 

[Taylortwocities]

The circuit(s) require protection with a 30mA RCD. A 100mA RCD does not provide the protection required.

So, lets suppose you buy a (used or new) RCD from FleaBay.
How will you test that it will trip (or even works). Do you have an RCD tester?

Per the above, better to leave it to your spark.

PS He could just put a nice new RCD in an enclosure and connect it before the existing consumer unit. Not the best practise as it means that a single fault will plunge the entire house into darkness.

 

[1john]

Cant you get RCBO's for the board?