Under floorboard JBs

[yellowvanman]

Been asked to install some smoke alarms - all to interconnect wirelessly, over 4 floors.

Have put in the cable as the landings and stairwell were going to be carpeted, and routed the cable to a nearby JB (in a room without carpet at the moment). JBs under floorboards have a number of wires entering from all four directions, I would usually swap this out for a wagobox (or similar) but in some cases there isn't enough slack on the cables to make this work.

Tempted to just wire into the JBs, as they've probably been there for over 30 years without any problems and mention something about the JBs in the cert.

What are my other options?

 

[Leesparkykent]

Been asked to install some smoke alarms - all to interconnect wirelessly, over 4 floors.

Have put in the cable as the landings and stairwell were going to be carpeted, and routed the cable to a nearby JB (in a room without carpet at the moment). JBs under floorboards have a number of wires entering from all four directions, I would usually swap this out for a wagobox (or similar) but in some cases there isn't enough slack on the cables to make this work.

Tempted to just wire into the JBs, as they've probably been there for over 30 years without any problems and mention something about the JBs in the cert.

What are my other options?

Technical Properties J804

Is there enough slack to change the existing JB for one of these?

 

[yellowvanman]

Technical Properties J804

Is there enough slack to change the existing JB for one of these?

Some JBs have >4 cables

 

[Richard Burns]

Despite the fact that I have just spent two days pulling up floorboards to find a fault in a lighting circuit with all the junction boxes in the floor and it was right nightmare (especially to find it was a borrowed neutral to another circuit with a fault that was making the lighting circuit show as faulty).
as I say despite this I would tend to wire into the existing JBs.
Properly you should put in MF junction boxes and if the cables are too short then add in extension MF junction boxes.
If you leave any non MF JBs then the circuit is already compromised.
Ideally reroute all the cables (extending them with crimps and heat shrink) out from under the floor.,
Even an MF junction box under the floor with multiple connections may need to be accessed at some point for testing/fault finding.

 

[Leesparkykent]

Some JBs have >4 cables

Find what one is the feed, disconnect it, put it in a MF junction box along with feed for smoke and take another one out to reconnect into existing JB.

 

[SS-2015]

Find feed - cut into that and put an MF JB in there and don't even touch existing JB's

 

[7029 dave]

Find feed - cut into that and put an MF JB in there and don't even touch existing JB's

That to me is ridiculous, why?, all you are doing is adding an other joint.

 

[SS-2015]

That to me is ridiculous, why?, all you are doing is adding an other joint.

Whats wrong with that? Providing it's all done correctly of course...
Saves disturbing the JB's that have been there for "30 years"

 

[7029 dave]

Whats wrong with that? Providing it's all done correctly of course...
Saves disturbing the JB's that have been there for "30 years"

Terminate into jb that is already in situ.

 

[SS-2015]

Each to their own I guess.

 

[Simonslimline]

Terminate into jb that is already in situ.

Even if it is already full?

 

[7029 dave]

Even if it is already full?

Is it, use an j701, if full to capacity then he will have to cut in, but not as first option.

 

[overskilled]

Personally be tempted to crimp extend and heat shrink into a new mf box

 

[IzzyS]

Been asked to install some smoke alarms - all to interconnect wirelessly, over 4 floors.

Have put in the cable as the landings and stairwell were going to be carpeted, and routed the cable to a nearby JB (in a room without carpet at the moment). JBs under floorboards have a number of wires entering from all four directions, I would usually swap this out for a wagobox (or similar) but in some cases there isn't enough slack on the cables to make this work.

Tempted to just wire into the JBs, as they've probably been there for over 30 years without any problems and mention something about the JBs in the cert.

What are my other options?

Crack on. You're managing to access the JB, so it must be accessible!

BTW, plumbers have a different interpretation as to what is accessible. WRAS guidance states:

The presence of the following surface finishes, appliances and structural fixtures are not considered to be obstacles which make an installation inaccessible or renders access difficult:-
• Ceramic, stone quarry tiles
• Floor and wall tiles (all materials)
• Laminate and other wood finishes
• Carpet and carpet tiles
• Vinyl
• Ceiling tiles
• White goods
• Screed
• Bath panels
• Bathroom modular systems
• Removable panels
• Chip board flooring
• Raised modular flooring
• Bespoke access hatches
[Please note that this is a representative not exhaustive or definitive list]

Maybe lifting a carpet isn't that hard after all. Probably best to note the JB's position on the certificate though - leaking electricity isn't as easy to spot as leaking water.

 

[Octopus]

Crack on. You're managing to access the JB, so it must be accessible!

BTW, plumbers have a different interpretation as to what is accessible. WRAS guidance states:

The presence of the following surface finishes, appliances and structural fixtures are not considered to be obstacles which make an installation inaccessible or renders access difficult:-
• Ceramic, stone quarry tiles
• Floor and wall tiles (all materials)
• Laminate and other wood finishes
• Carpet and carpet tiles
• Vinyl
• Ceiling tiles
• White goods
• Screed
• Bath panels
• Bathroom modular systems
• Removable panels
• Chip board flooring
• Raised modular flooring
• Bespoke access hatches
[Please note that this is a representative not exhaustive or definitive list]

Maybe lifting a carpet isn't that hard after all. Probably best to note the JB's position on the certificate though - leaking electricity isn't as easy to spot as leaking water.

In bold - are they for real??