S
Siddell
Hi there,
I've got an old, Wylex, 4-way, rewireable fusebox, water mains providing my earth (PME to come) and a 100A service fuse. The circuits are:
i) ring main
ii) lighting (two circuits in single fuseway, one of which is a single light)
iii) immersion heater (not used)
iv) cooker and hob (actually leads to a double socket that feeds these appliances).
Once I've sorted my bonding, I'll get someone in to connect to the new PME terminal. What I need to decide, though, is what RCD protection to get. What I would like is to keep the fusebox and simply have someone install one, all-encompassing RCD. I am aware of regs 314.1 and 314.2 (which ordinarily even a dual RCD, split-load CU doesn't seem to satisfy) and that the only practical solution to that is to pretty much have each circuit individually protected by RCBOs, so would like to park that issue aside for now, given that I don't mind nuisance trips as long as they are infrequent, which brings me (finally) to my questions!
What is the likelihood and nature of any nuisance trips if one RCD were installed for the whole fusebox?
I know this may be something of a crystal ball question, but really I need to weigh up the chance and cost of problems (likely a new CU) against the cost of installing a single RCD. The only time a fuse has blown in the two years I've been in the house was on the lighting circuit, so no other obvious signs of earth leakage - that said, I probably have a sh*tty earth right now and any earth leakage I assume will be magnified once the PME connection is made.
To what extent could this be mitigated using a 100ma RCD (as opposed to 30ma)? Where is a 30ma RCD required? Is there an inherent firerisk with rewireable fuses slow fusing if only slightly overloaded?
Thanks for taking the time to read this and for your thoughts.
I've got an old, Wylex, 4-way, rewireable fusebox, water mains providing my earth (PME to come) and a 100A service fuse. The circuits are:
i) ring main
ii) lighting (two circuits in single fuseway, one of which is a single light)
iii) immersion heater (not used)
iv) cooker and hob (actually leads to a double socket that feeds these appliances).
Once I've sorted my bonding, I'll get someone in to connect to the new PME terminal. What I need to decide, though, is what RCD protection to get. What I would like is to keep the fusebox and simply have someone install one, all-encompassing RCD. I am aware of regs 314.1 and 314.2 (which ordinarily even a dual RCD, split-load CU doesn't seem to satisfy) and that the only practical solution to that is to pretty much have each circuit individually protected by RCBOs, so would like to park that issue aside for now, given that I don't mind nuisance trips as long as they are infrequent, which brings me (finally) to my questions!
What is the likelihood and nature of any nuisance trips if one RCD were installed for the whole fusebox?
I know this may be something of a crystal ball question, but really I need to weigh up the chance and cost of problems (likely a new CU) against the cost of installing a single RCD. The only time a fuse has blown in the two years I've been in the house was on the lighting circuit, so no other obvious signs of earth leakage - that said, I probably have a sh*tty earth right now and any earth leakage I assume will be magnified once the PME connection is made.
To what extent could this be mitigated using a 100ma RCD (as opposed to 30ma)? Where is a 30ma RCD required? Is there an inherent firerisk with rewireable fuses slow fusing if only slightly overloaded?
Thanks for taking the time to read this and for your thoughts.
