replacing old fusebox

[robmar0se]

We have an old 1930's fuse box with integral master switch which we are replacing with a CU. Incidentally the house extension has its own circuits and CU. Both circuits are supplied through one one meter and supplier master circuit breaker.

There is a (heavy) splitter box for the two circuits.

To disable to power supply to the old fuse box, I could just remove the cables from the splitter box, preferably I'd like to disable the power altogether - the only way I can see to do this is to break the seal on the master circuit breaker - am I allowed to do this? Anyway round this?

 

[catdog1121]

We have an old 1930's fuse box with integral master switch which we are replacing with a CU. Incidentally the house extension has its own circuits and CU. Both circuits are supplied through one one meter and supplier master circuit breaker.

There is a (heavy) splitter box for the two circuits.

To disable to power supply to the old fuse box, I could just remove the cables from the splitter box, preferably I'd like to disable the power altogether - the only way I can see to do this is to break the seal on the master circuit breaker - am I allowed to do this? Anyway round this?

Are you a qualified electrician and part of a cps scheme? Changing a consumer unit is notifiable work that you should not be doing youself.

 

[timhoward]

I'm not sure where (roughly) the OP lives as "lichens" is not turning up on google maps.
But if we are talking about the UK, generally replacing a consumer unit is a job which requires a building control certificate as it comes under part P of building regs. There are three ways to do this but the easiest is to get someone who is part of a competent persons scheme to do the work. (NICEIC / Napit / Stroma etc.)

To answer the question you shouldn't touch anything upstream of the meter tails, including the suppliers fuse. If you are going ahead anyway my advice would be to ask the supplier to fit an isolator.

I'd also advise that it would be very wise to get some insulation resistance testing done before the CU is changed. If the wiring is also 1930's there could be nuisance tripping issues or worse when connected to RCD or RCBO devices found in modern consumer units.

 

[James]

A picture or 2 might help us help you on this one

 

[Mikegh]

Surely 1930s installation is due a rewire

As I can also envisage problems arising immediately with the RCDs/rcbos

 

[robmar0se]

Are you a qualified electrician and part of a cps scheme? Changing a consumer unit is notifiable work that you should not be doing youself.

Thank you. no I'm not, but I have considerable experience with electrical installations..

I was hoping to get some practical advice, I already have the CU and am happy with the rewiring necessary, my only concern to do it properly is to cut the supply.

Surely 1930s installation is due a rewire

As I can also envisage problems arising immediately with the RCDs/rcbos

Hi Thanks, am aware of that risk, have checked the cabling as far as possible, insulation appears in good order (without doing Ohms law testing of insulation resistence).

 

[loz2754]

In England, it's not permitted to break a supplier's seal, either on the meter or the main cutout fuse. You would need to call your DNO for them to withdraw the main fuse, and for them to put it back in when you're ready.

 

[pc1966]

Hi Thanks, am aware of that risk, have checked the cabling as far as possible, insulation appears in good order (without doing Ohms law testing of insulation resistence).

There are many ways an old cut-out can fail catastrophically when attempting to pull the fuse so DO NOT DO IT!

Most folk on here know about the seal faerie but also know never to touch and old or damaged cut-out even if they have suitable arc-flash PPE as it could end very badly indeed.

If the cut out is old and in any doubt contact the DNO about having it replaced and an isolator fitted, then you can safely do any CU work. But remember in England & Wales that comes under Part P of the building regulations as notifiable work.

 

[catdog1121]

Thank you. no I'm not, but I have considerable experience with electrical installations..

I was hoping to get some practical advice, I already have the CU and am happy with the rewiring necessary, my only concern to do it properly is to cut the supply.

Hi Thanks, am aware of that risk, have checked the cabling as far as possible, insulation appears in good order (without doing Ohms law testing of insulation resistence).

Even if you have "considerable experience". Are you aware of say the new SPD requirements, have you got the required equipment to carry out the testing required? How are you going to register this work to gain a compliance certificate from building control?

There is no such thing as "Ohms law testing of insulation resistance".

It is quite clear from the few messages you have posted that you do not have the qualifications, knowledge, equipment or authority to carry out this work....

There is a worrying number of people that seem to think a consumer unit swap is a DIY job.

 

[LewisM]

Thank you. no I'm not, but I have considerable experience with electrical installations..

I was hoping to get some practical advice, I already have the CU and am happy with the rewiring necessary, my only concern to do it properly is to cut the supply.

Hi Thanks, am aware of that risk, have checked the cabling as far as possible, insulation appears in good order (without doing Ohms law testing of insulation resistence).

So how will you test it after you have changed the CU ?

Even simply testing RCBOs/RCDs, just because it trips when you press test doesn't mean that it's disconnecting in the permitted times

 

[timhoward]

I don't know if I can express this properly, but I'll have a go....

We are going back 25 years, but before I properly trained I fiddled with electrics a lot, I got an appreciation for current carrying capacity of cables and appropriate upstream protection, matched cable size to fuses or breakers, did my best to work neatly, support cables, make good connections. I would have said I had experience of electrical installations. I even blagged some three phase work in a factory and figured out how to calculate how much current per phase machines drew, and what size cable and fuses they would need. At the end of a task I could always say I've done my best and that should be ok. I now look back and hope to goodness someone has checked over those installations since. I didn't own any test equipment other than a multi-meter. Not even a 2 pole tester.

The difference today (years later) after training and learning testing and inspection, is that I can look at an entire installation from the supply onwards and prove beyond doubt that everything is going to be ok before it's energised, the circuits are designed so fault protection will operate, the fault current to operate breakers/fuses within defined limits is achievable in practise, fuses will blow, breakers will trip, the wiring is in good condition, additional protection is working properly within defined time limits, earthing and bonding is adequate etc. Understanding the three (main) different earthing setups in common use in the UK and the effect each has on how you do things. I could go on.

Until you get to that stage where it hits you you can confidently say "this meets the regs and I've proved it's safe to use" you don't really realise the amount of things you couldn't verify before either because no one's shown you it needs doing or due to lack of fairly expensive testing equipment , knowledge of how to use it, and experience of interpreting results.

I'd never blame anyone for having ambitions as I'd be a complete hypocrite to say people shouldn't do things. The hard bit is explaining to people that there is honestly and genuinely more to know to do something safely than they think there is, without it coming across as "we're all better than you" and being counter-productive. It usually has nothing to do with people's ability either, just their knowledge and experience.

Sorry that turned into an essay, but my point is that if you don't have inspection and testing experience you shouldn't change a consumer unit. I didn't appreciate this myself once until I was blown away by how much I didn't in fact know.

 

[nicebutdim]

That ought to be pinned in all help sections ?

 

[telectrix]

I don't know if I can express this properly, but I'll have a go....

We are going back 25 years, but before I properly trained I fiddled with electrics a lot, I got an appreciation for current carrying capacity of cables and appropriate upstream protection, matched cable size to fuses or breakers, did my best to work neatly, support cables, make good connections. I would have said I had experience of electrical installations. I even blagged some three phase work in a factory and figured out how to calculate how much current per phase machines drew, and what size cable and fuses they would need. At the end of a task I could always say I've done my best and that should be ok. I now look back and hope to goodness someone has checked over those installations since. I didn't own any test equipment other than a multi-meter. Not even a 2 pole tester.

The difference today (years later) after training and learning testing and inspection, is that I can look at an entire installation from the supply onwards and prove beyond doubt that everything is going to be ok before it's energised, the circuits are designed so fault protection will operate, the fault current to operate breakers/fuses within defined limits is achievable in practise, fuses will blow, breakers will trip, the wiring is in good condition, additional protection is working properly within defined time limits, earthing and bonding is adequate etc. Understanding the three (main) different earthing setups in common use in the UK and the effect each has on how you do things. I could go on.

Until you get to that stage where it hits you you can confidently say "this meets the regs and I've proved it's safe to use" you don't really realise the amount of things you couldn't verify before either because no one's shown you it needs doing or due to lack of fairly expensive testing equipment , knowledge of how to use it, and experience of interpreting results.

I'd never blame anyone for having ambitions as I'd be a complete hypocrite to say people shouldn't do things. The hard bit is explaining to people that there is honestly and genuinely more to know to do something safely than they think there is, without it coming across as "we're all better than you" and being counter-productive. It usually has nothing to do with people's ability either, just their knowledge and experience.

Sorry that turned into an essay, but my point is that if you don't have inspection and testing experience you shouldn't change a consumer unit. I didn't appreciate this myself once until I was blown away by how much I didn't in fact know.

you could apply all that to me in my earlier life. transitioned from industrial electronics when valves were being superceded by transistors. but to my knowledge, nobody has been injured or any fires started from my earlier efforts.

 

[freddo]

I'd still like to see some photos of this old wiring, I love seeing old stuff.