Consumer unit capacity help required

[JohnW2]

There's no requirement to have an RCD. It's going to be a completely unnecessary device which may lead to problems.

Perhaps not for the kiln, but if there is no RCD at the origin of the new circuit, that could obviously have implications in terms of the type of cable and/or routing of cable for the circuit.

A kiln is essentially just a type of 'oven'. Does that mean that you routinely install non-RCD-protected cooker circuits?

Kind Regards, John

 

[RF Lighting]

It seems that since the introduction of BS7671:2008 everyone now automatically RCDs everything without pausing to think if this the best installation method.

 

[RF Lighting]

There's no requirement to have an RCD. It's going to be a completely unnecessary device which may lead to problems.

Perhaps not for the kiln, but if there is no RCD at the origin of the new circuit, that could obviously have implications in terms of the type of cable and/or routing of cable for the circuit.

A kiln is essentially just a type of 'oven'. Does that mean that you routinely install non-RCD-protected cooker circuits?

Kind Regards, John

Whilst it's rare for me to install domestic ovens, yes I do where possible as it is a better design.

 

[JohnW2]

It seems that since the introduction of BS7671:2008 everyone now automatically RCDs everything without pausing to think if this the best installation method.

That's probably true up to a point but, in practice, there probably aren't that many circuits which don't have at least some bits of cable which require RCD protection - so, unless (unusually) one is working with steel conduit, or pyro/SWA etc., it almost is the case that every circuit needs RCD protection.

Kind Regards, John

 

[JohnW2]

A kiln is essentially just a type of 'oven'. Does that mean that you routinely install non-RCD-protected cooker circuits?

Whilst it's rare for me to install domestic ovens, yes I do where possible as it is a better design.

I didn't expect you to install many ovens, but I thought that you might install cooker circuits (not the least, during 're-wires'). Do you not have difficulty routing the cabling such that it does not require RCD protection?

Kind Regards, John

 

[RF Lighting]

I don't really do much in the way of domestic work, but It's dead easy. Half a meter of steel tube between the isolator position running to just below worktop height, then run the cables surface or in PVC trunking and RCD is not required.

 

[ban-all-sheds]

I don't really do much in the way of domestic work, but It's dead easy. Half a meter of steel tube between the isolator position running to just below worktop height, then run the cables surface or in PVC trunking and RCD is not required.

(unless the cooker switch has a socket)

Given the known predilection for heating elements to develop cracks and temporary earth leakage, I would say that avoiding RCDs on kilns was prudent.

 

[JohnW2]

I don't really do much in the way of domestic work, but It's dead easy. Half a meter of steel tube between the isolator position running to just below worktop height, then run the cables surface or in PVC trunking and RCD is not required.

That rather depends upon how the electricity gets from the CU to the 'isolator position', doesn't it?

Kind Regards, John

 

[oldbutnotdead]

Why do some people have such a downer on RCDs in domestic environments? In my work (thyristor/triac dimmers) they can be a nuisance at times but at home they're an excellent 'if all else fails' protection- I really don't want my last memories of this life to be hanging on to an oven door handle going OW 50 times a second.
When I moved in here (24 years ago) an early job was an RCD on the power circuits (the lighting and alarm are not on the RCD). It has tripped unexpectedly about 10 times- each time it tripped it was on a valid fault- oven insulation resistance L-E had dropped to 0.5MΩ at anything above 200C, cordless kettle base had got wet, hedge trimmer cable had a nick in it which when dragged through damp grass passed fault current, shed outside light was full of water (that was weird, TH lamp actually worked for about a second even though it was submerged. Lasted another year after I emptied the water out as well). And that's it. What's not to like? Especially nowadays- always hated those crappy metal plates you were meant to spike over joist notches. Stick and RCD in line instead and stop worrying

 

[RF Lighting]

An RCD isn't a licence to lash in cables wherever you feel like it!

We've got this clever thing called earthing to make your oven safe if all else fails. It's worked for years and years.

 

[JohnW2]

An RCD isn't a licence to lash in cables wherever you feel like it! We've got this clever thing called earthing to make your oven safe if all else fails. It's worked for years and years.

As you know, I'm not the most passionate of campaigners for RCDs as a means of mitigating the effects of electric shocks, but I definitely do see them as having a place in the prevention of shocks in the first place (by operating in response to a fault, before anyone has suffered a shock). The problem with conventional fault protection in a TN installation (EEBADS, or whatever you want to call it) is that it necessarily assumes an L-E fault of 'negligible impedance' - the moment one has a 'non-negligible' (albeit still low) impedance fault, it would usually/often be impossible/ impracticable to have a low enough Zs for an OPD to operate, even though substantial 'touch voltages' could theoretically be present (and persistent). In contrast, an RCD will operate in the face of a L-E fault of appreciable impedance.

Kind Regards, John