Discuss Extra RCD on off peak F / Obsolete Switch / Economy 7 / Retro fit MCB's in the UK Electrical Forum area at ElectriciansForums.net

P

Paul Silver

Hi, I'm not an electrician, I wonder if anyone can help me with a few queries.

Q1. Can you explain what this 40A RCD might be for (Off Peak F)?

I have a cartridge fuse board from the standard meter (house built in 1970).
The original heating (fed through the off peak F meter) was obsolete in the late 1980's, and storage heaters installed. The storage heaters are connected to a separate consumer unit (MCB's?) , with a 63A RCD.
What's puzzling to me is that there's a 40A RCD connected between the cartridge board (standard energy) and the 63A consumer unit for the heating (off peak F).

The cartridge fuses are as more or less as expected, 5A lights, 5A lights, 15A immersion (dual supply), 30A sockets, 30A cooker.

If the 40A RCD is turned off everything still works.
Can anyone explain what this RCD might be for/why there might be a connection between the supplies. (It doesn't turn off the dual immersion supply either).

Q2. Removal of old TV supply from henley blocks direct from meter.

It's an end of terrace ex council house, and there used to be one TV aerial outside, with a splitter box supplying the tv signal to the other houses. This was removed years ago, but the supply switch is still connected.
The output from the standard meter connects to henley blocks - routed to both the cartridge fuse board, and the old TV supply switch (so the old switch isn't fused, or connected to the fuse board).

To disconnect this switch, would that be a job for an electrician, or SSE?

Q3 I'm thinking about changing from off peak F to economy 7. SSE weren't particularly helpful in explaining what I need to do, other than get an electrician to swap the supply to the heating from the off peak meter to the standard meter prior to the meter change.
Is it as simple as disconnect from one, and move to the other? Or more complicated?

I'm trying to guesstimate if switching from F to 7 would be beneficial.
Currently 78% of energy use is through off peak F, and 22% standard energy.
However comparing this to economy 7 isn't straight forward, as 2.75 hours of the off peak usage would fall under the standard energy rate for economy 7. Using the washing machine at night might counter balance a bit...
The switch would see a saving of 4p per unit from F to 7,
an increase of 3p per unit for standard energy/day rate,
but possibly a change of 25% energy usage moved from the discounted rate, to the higher rate....

Can't decide if best to stick with F (through SSE), or switch to economy 7 to enable switching supplier for better economy 7 rates down the line...!
So knowing whats involved with preparing the electrics would be helpful in the decision!!!

Q4 Wylex retro fit MCB's
One of the cartridge fuses was replaced with an MCB (about 20 years ago) - Wylex retro fit into old standard range units (and it is a Wylex fuse board!).
Whilst I appreciate fitting a new consumer unit would mean a wiring inspection which would be the best option long term, for now would replacing the rest of the cartridge fuses be a sensible short term move?
 

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Replacing the cartridge fuses with mcbs will offer no better protection, and if the earth fault loop impedance of the circuits is too high then the mcbs may be worse than the cartridge fuses.
The mcbs will provide the convenience of being easier to reset after they have operated.

It's hard to say what the mystery RCD is doing without seeing it, it could be a 24hr supply for the boost element in the hot water cylinder.
 
Hi, I'm not an electrician, I wonder if anyone can help me with a few queries.

Q1. Can you explain what this 40A RCD might be for (Off Peak F)?

I have a cartridge fuse board from the standard meter (house built in 1970).
The original heating (fed through the off peak F meter) was obsolete in the late 1980's, and storage heaters installed. The storage heaters are connected to a separate consumer unit (MCB's?) , with a 63A RCD.
What's puzzling to me is that there's a 40A RCD connected between the cartridge board (standard energy) and the 63A consumer unit for the heating (off peak F).

The cartridge fuses are as more or less as expected, 5A lights, 5A lights, 15A immersion (dual supply), 30A sockets, 30A cooker.

If the 40A RCD is turned off everything still works.
Can anyone explain what this RCD might be for/why there might be a connection between the supplies. (It doesn't turn off the dual immersion supply either).

Q2. Removal of old TV supply from henley blocks direct from meter.

It's an end of terrace ex council house, and there used to be one TV aerial outside, with a splitter box supplying the tv signal to the other houses. This was removed years ago, but the supply switch is still connected.
The output from the standard meter connects to henley blocks - routed to both the cartridge fuse board, and the old TV supply switch (so the old switch isn't fused, or connected to the fuse board).

To disconnect this switch, would that be a job for an electrician, or SSE?

Q3 I'm thinking about changing from off peak F to economy 7. SSE weren't particularly helpful in explaining what I need to do, other than get an electrician to swap the supply to the heating from the off peak meter to the standard meter prior to the meter change.
Is it as simple as disconnect from one, and move to the other? Or more complicated?

I'm trying to guesstimate if switching from F to 7 would be beneficial.
Currently 78% of energy use is through off peak F, and 22% standard energy.
However comparing this to economy 7 isn't straight forward, as 2.75 hours of the off peak usage would fall under the standard energy rate for economy 7. Using the washing machine at night might counter balance a bit...
The switch would see a saving of 4p per unit from F to 7,
an increase of 3p per unit for standard energy/day rate,
but possibly a change of 25% energy usage moved from the discounted rate, to the higher rate....

Can't decide if best to stick with F (through SSE), or switch to economy 7 to enable switching supplier for better economy 7 rates down the line...!
So knowing whats involved with preparing the electrics would be helpful in the decision!!!

Q4 Wylex retro fit MCB's
One of the cartridge fuses was replaced with an MCB (about 20 years ago) - Wylex retro fit into old standard range units (and it is a Wylex fuse board!).
Whilst I appreciate fitting a new consumer unit would mean a wiring inspection which would be the best option long term, for now would replacing the rest of the cartridge fuses be a sensible short term move?
Can you post a picture of the entire set up? as a lay person your post is a trifle hard to follow, no disrespect intended, but we can be a dumb bunch at times and a picture paints a better picture of what has been done. Or at least I can be a bit dumb at times, the others I'm not so sure.
 
Can you post a picture of the entire set up? as a lay person your post is a trifle hard to follow, no disrespect intended, but we can be a dumb bunch at times and a picture paints a better picture of what has been done. Or at least I can be a bit dumb at times, the others I'm not so sure.
PDF attached!
 
Replacing the cartridge fuses with mcbs will offer no better protection, and if the earth fault loop impedance of the circuits is too high then the mcbs may be worse than the cartridge fuses.
The mcbs will provide the convenience of being easier to reset after they have operated.

Thanks Dave, so might as well leave as is
 
Can you post a picture of the entire set up? as a lay person your post is a trifle hard to follow, no disrespect intended, but we can be a dumb bunch at times and a picture paints a better picture of what has been done. Or at least I can be a bit dumb at times, the others I'm not so sure.
Prob not clear enough, just made as my profile picture
 
that stand-alone RCD may have been added to your socket circuit. whatever, you need an electrician on site to sort that mess out.
 
Here's a close up of the RCD. The white box is the heating (from the off peak F), and the grey fuse box the lights, sockets, etc. It's the 40amp RCD between the two that doesn't make sense to me...! RCD.JPG
 
it may not connect to the off peak CU, the cable could just pass through or behind. can't tell without the covers being taken off.
 
Does the rcd operate when you use the test button, if yes pull the fuses from the grey board until it does not to find the circuit it protects.
 

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