Joining different size cables

[MikeJhn]

Which in an existing installation is irrelevant

What ever makes you think that existing installations are exempt from the CDM Regulations? If you are the designer in an existing or new installation the CDM Regulations apply.

 

[Murdoch]

What ever makes you think that existing installations are exempt from the CDM Regulations? If you are the designer in an existing or new installation the CDM Regulations apply.

Because they are

 

[MikeJhn]

Please read this: https://www.citb.co.uk/about-citb/p...gement),, conversions, repair and maintenance.

 

[Murdoch]

Please read this: https://www.citb.co.uk/about-citb/partnerships-and-initiatives/construction-design-and-management-regulations-2015/cdm-regulations/#:~:text=The Construction (Design & Management),, conversions, repair and maintenance.

hum. You need to be more specific ….

 

[MikeJhn]

Just read the text and take in that maintenance is included under the CDM Regulations.

 

[MikeJhn]

not familiar with Part M then?

@Murdoch You have miss interpreted Part M and the CDM Regulations, I suggest you become more familiar with them before miss quoting their meaning.

 

[SPECIAL LOCATION]

@Murdoch it's you that is not familiar with Part M or the CDM Regulations

Not 100% about which bits of Part M and/or CDM regulations apply to "Joining Different Sized Cables" as per the Op's original question??

Any help, much appreciated?

( P.S I have only skip-read some of the posts... so I could possibly have missed something!)

 

[Sidewinder]

AFAIK, ALL, construction work is covered by CDM, new work, modifications, or maintenance.
Now whether CDM requires us to modify existing work when subject to maintenance, if it wasn't originally complaint, is another matter, & one I am unsure about.
The aspect of CDM I am thinking about here is maintainability.

 

[MikeJhn]

I was thinking more about replacing a CU or modifications to a circuit, this makes any electrician the Designer under the CDM Regs, therefore they have to take into account ease of installation and any future maintenance.

If existing work is non compliant, then if reasonably practicable the installation should be made compliant when next worked on.

 

[Murdoch]

If existing work is non compliant, then if reasonably practicable the installation should be made compliant when next worked on.

Simply CBA with such unnecessary addition of work suggestions to hard pressed home owners .............. on the basis that extremely few existing older installations would meet Part M with respect to the CU position

 

[MikeJhn]

on the basis that extremely few existing older installations would meet Part M with respect to the CU position

Part M has nothing to do with positioning of equipment it is to do with accessibility to buildings, not only for disabled people, those with limited mobility and wheelchair users, but also to people who regularly use prams and other wheeled devices.

 

[Murdoch]

Part M has nothing to do with positioning of equipment it is to do with accessibility to buildings, not only for disabled people, those with limited mobility and wheelchair users, but also to people who regularly use prams and other wheeled devices.

but includes this:

 

[MikeJhn]

Which is to do with disabled access and is not mandatory for those buildings without the requirement for access by disabled people, those with limited mobility and wheelchair users.

 

[Murdoch]

Which is to do with disabled access and is not mandatory for those buildings without the requirement for access by disabled people, those with limited mobility and wheelchair users.

but you started this off thread topic suggesting that the link you provided says we have to relocate each and every CU to comply with the access regs


what is you point ?

 

[MikeJhn]

The topic went off thread when you quoted the Part M Regulations incorrectly.

What I said was that it is the responsibility of designers (electricians) under the CDM Regulations to ensure that equipment is easily accessible, so in the case of a CU replacement it should be considered if it is reasonably practicable to re-locate the CU to an easier access position if required.

 

[Murdoch]

under the CDM Regulations to ensure that equipment is easily accessible, so in the case of a CU replacement it should be considered if it is reasonably practicable to re-locate the CU to an easier access position if required.

Where does it say that?

 

[MikeJhn]

Read the requirements on Designers under the CDM Regulations.

 

[DonClif]

I'm currently training so this is a genuine question:
Am I understanding correctly, that OP wants to join a 4mm circuit to an existing 2.5mm ring?
As I understand from BS7671, you can spur with smaller cable using a fused spur, but no mention of increasing to a larger size for certain parts of the installation.
Also, isn't the cable supposed to be completely wired from start to finish based on the most detrimental part of the run?

Am I missing something?

Again, genuinely asking.

 

[binky]

I'm currently training so this is a genuine question:
Am I understanding correctly, that OP wants to join a 4mm circuit to an existing 2.5mm ring?
As I understand from BS7671, you can spur with smaller cable using a fused spur, but no mention of increasing to a larger size for certain parts of the installation.
Also, isn't the cable supposed to be completely wired from start to finish based on the most detrimental part of the run?

Am I missing something?

Again, genuinely asking.

You don't see it often, but it's perfectly acceptable to have multiple cable sizes in a circuit. It's often done for longer cable runs to reduce voltage drop. What matters is that the OCPD is sized correctly for the smallest cable/ installation factors such as insulation.

Probably the most likely scenario you will encounter this is where an old cooker circuit has been reused to feed a socket ring cct in a kitchen. Known as a 'lollipop' cct by many.