Maximum kW fixed load on RFC

[Zdb]

So if 2kW is the maximum fixed load for a 2.5mm RFC.

What would you say the maximum fixed load on a 4mm RFC should be? If different.

 

[UNG]

Begs the question why a 4mm² RFC is this because of volt drop over the circuit length as it is the only reason I have ever installed one

RFC is normally a 32A breaker

So 2 Kw still remains as the recommendation IMO

 

[Zdb]

Begs the question why a 4mm² RFC is this because of volt drop over the circuit length as it is the only reason I have ever installed one

RFC is normally a 32A breaker

So 2 Kw still remains as the recommendation IMO

Appendix 15 suggests that the 2kW limit is due to the current carrying capacity of the cable.

 

[Lucien Nunes]

The point of an RFC is to supply a diverse and distributed load, which allows the use of cable and accessories of lower rating than the OCPD. A single heavy load at one point could encourage overloading of one leg, but one could avoid cable overload by using a larger cable as suggested by the OP. 4mm² T+E Method 3 is OK on a 32A, so would withstand the whole 7.4kW load in one place on the ring. One would have to ensure that any connectors and accessories through which the circuit passes are OK for 32A as well.

However, returning to the original intent of the RFC, it might not be the most suitable option as all the cable then needs to be uprated instead of one radial to the large fixed load. Also, as a non-standard implementation of an otherwise standard circuit, in a domestic situation without technical oversight, inappropriate modifications could reasonably be foreseen (such as extending with 2.5mm²) and therefore the heavy point loads still inadvisable on a 32A RFC of any cable size.

 

[stevehasto1066]

Appendix 15 suggests that the 2kW limit is due to the current carrying capacity of the cable.

so if i had 2 X 1800W heaters could i connect these to one RFC that has only 5 sockets on it and has no significant load. so basically im asking is the 2KW combined or per fixed appliance

 

[pc1966]

so if i had 2 X 1800W heaters could i connect these to one RFC that has only 5 sockets on it and has no significant load. so basically im asking is the 2KW combined or per fixed appliance

Having multiple general-purpose heaters in different locations is OK, if fits the diversity of loads that the RFC is suited to.

Having them in the one location, or if they are unusually high duty cycle (like an immersion heater that can be on full for an hour or more, not cycling after several minutes like a typical thermostatic heater) would be pushing it.

 

[stevehasto1066]

Having multiple general-purpose heaters in different locations is OK, if fits the diversity of loads that the RFC is suited to.

Having them in the one location, or if they are unusually high duty cycle (like an immersion heater that can be on full for an hour or more, not cycling after several minutes like a typical thermostatic heater) would be pushing it.

 

[stevehasto1066]

This is the only part that concerns me. is it an overall 2KW or 2KW per load

 

[pc1966]

This is the only part that concerns me. is it an overall 2KW or 2KW per load

It is 2kW per load, with a maximum assumed of 26A => 6kW (not the typical 30A fuse / 32A MCB, see Table 7.1(i) in the On-Site guide).

The "comprehensive space heating" really is about having multiple heaters as part of the overall house heating on separate supplies.