Conservatory wiring

[akwoody2]

Hello,

so iv been asked to wire a conservatory that's been built, an electrician had stared it but didn't finish it due to health reasons. What I mean by started it he has chased in one twin back box and put one 2.5 t+e in. The other end of the cable is poking out the corner of the room through the mortar. My only guess is he was going to chase along the mortar to the next socket because it's built with exposed brick work, a very nice finish. The ring I will be tapping into is on a RCD, but i can't think of any other way to conceal the cable. I personally have never ran a cable under the mortar and never seen it done. Is it acceptable? If not how will I conceal the cable without damaging the brickwork?

I hope that made sense, if not then please ask me a question and I'll do my best to make it clearer.

thanks

 

[shanky887614]

Hello,

so iv been asked to wire a conservatory that's been built, an electrician had stared it but didn't finish it due to health reasons. What I mean by started it he has chased in one twin back box and put one 2.5 t+e in. The other end of the cable is poking out the corner of the room through the mortar. My only guess is he was going to chase along the mortar to the next socket because it's built with exposed brick work, a very nice finish. The ring I will be tapping into is on a RCD, but i can't think of any other way to conceal the cable. I personally have never ran a cable under the mortar and never seen it done. Is it acceptable? If not how will I conceal the cable without damaging the brickwork?

I hope that made sense, if not then please ask me a question and I'll do my best to make it clearer.

thanks

what is on the other side of the wall?

is back entry not possible or if its against a wall a bit of conduit hidden.

pictures would help.

 

[telectrix]

could you drill outside then black pvc tube then back in at the other socket location?

 

[akwoody2]

what is on the other side of the wall?

is back entry not possible or if its against a wall a bit of conduit hidden.

pictures would help.

i instantly regret not taking photos, sorry.

The cable is coming out the corner of the room through the mortar, the socket it needs to go to is a foot along the wall. I will then go through he back of that socket, into the house to pick up my supply. I want to avoid anything surface if possible because it will ruin the brick work look. I'm guessing he was going to chase the mortar out and run it down the channel and re mortar it.

 

[Engineer54]

Only ever wired up one conservatory for a friend, i used the cavity to run the socket cables, the exterior cavity brick walls are generally only 18'' or so high, the rest being glass panels and windows.

And no, i have no concerns at all with using the cavity space!!

 

[ipf]

Only ever wired up one conservatory for a friend, i used the cavity to run the socket cables, the exterior cavity brick walls are generally only 18'' or so high, the rest being glass panels and windows.

And no, i have no concerns at all with using the cavity space!!

Yes, wiring in the dwarf walls not the slightest concern. Not much load involved so two sfc's in the downstairs ring for sockets and lights in conservatory. MT2 generally not out of place for lighting, if required. I'm sure any problems can be assessed and sorted.

 

[Baker1988]

Only ever wired up one conservatory for a friend, i used the cavity to run the socket cables, the exterior cavity brick walls are generally only 18'' or so high, the rest being glass panels and windows.

And no, i have no concerns at all with using the cavity space!!

I agree with you about the cavity wall but i have been told a few times i should not put any cable into the cavity without any mechanical protection like conduit or something, so is it not against regs to put a cable in the cavity without mechanical protection? Sorry if its a daft question but this is how we learn.

 

[akwoody2]

I agree with you about the cavity wall but i have been told a few times i should not put any cable into the cavity without any mechanical protection like conduit or something, so is it not against regs to put a cable in the cavity without mechanical protection? Sorry if its a daft question but this is how we learn.

As as far as I know it doesn't need mechanical protection as long as it's on a RCD. Is that right?

So is it ok to carry on with the previous sparks idea about taking a little bit of mortar joint out inside the conservatory and placing the cable also the joint then re mortar over the cable?

 

[Engineer54]

It's not a method i would ever contemplate using, and i certainly wouldn't be burying a joint in the mortar!! That's just asking for trouble...

 

[Paul P]

It's not a method i would ever contemplate using, and i certainly wouldn't be burying a joint in the mortar!! That's just asking for trouble...

I think you may of miss read the joint thing. I think he means a mortar joint not a cable joint?

I can't see a problem with it as long as it is a designated cable run location.

 

[davesparks]

When I was an apprentice I was taught that it is unacceptable to take out mortar joints and bury cables in them. And so I would never do it, but I think it would be quite hard to find regulations that prevent it.

 

[shanky887614]

When I was an apprentice I was taught that it is unacceptable to take out mortar joints and bury cables in them. And so I would never do it, but I think it would be quite hard to find regulations that prevent it.

i think i understand how his conservatory is laid out with the old external wall unplastered.

i think its lazy and should be plastered as well.

personally i would have the socket on the feature wall spurred off the one behind then a supply cable gotten from elseware.

two adaptable boxes and some swa wouldn't look out of place outside but it depends on scenario

 

[Richard Burns]

I agree with you about the cavity wall but i have been told a few times i should not put any cable into the cavity without any mechanical protection like conduit or something, so is it not against regs to put a cable in the cavity without mechanical protection? Sorry if its a daft question but this is how we learn.

Just my opinion of how the advice stands is that:
If you install a cable unprotected in a cavity it may become damaged and you would be unaware of this.
If you install a cable hanging down the cavity it may be subjected to excessive strain (even though 5m is permitted if it is not over a sharp edge!)
If you install a cable across the cavity then you will bridge the cavity and possibly permit moisture to reach the internal wall (this is mentioned in Approved document C that the cavity should only be bridged by wall ties, cavity trays, fire stops and cavity closures) (drill at an angle to direct drips to the outside wall).
If there is a loose cable in the cavity then it could coil and twist so that it bridges the cavity.
However I am not sure that there are any regulations to stop you doing this, there are only building guidance recommendations.

 

[akwoody2]

Just my opinion of how the advice stands is that:
If you install a cable unprotected in a cavity it may become damaged and you would be unaware of this.
If you install a cable hanging down the cavity it may be subjected to excessive strain (even though 5m is permitted if it is not over a sharp edge!)
If you install a cable across the cavity then you will bridge the cavity and possibly permit moisture to reach the internal wall (this is mentioned in Approved document C that the cavity should only be bridged by wall ties, cavity trays, fire stops and cavity closures) (drill at an angle to direct drips to the outside wall).
If there is a loose cable in the cavity then it could coil and twist so that it bridges the cavity.
However I am not sure that there are any regulations to stop you doing this, there are only building guidance recommendations.

Iv attached a paint drawing, sorry I had 2mins to do it.

So the top right cable needs to go to the socket to the left. its a decorative brick wall so I can only assume the previous spark was going to remove the mortar to run the cable then re-mortar. If I can help it I don't want to run it surface.

Hope the poor drawing clears it up.

 

[shanky887614]

Iv attached a paint drawing, sorry I had 2mins to do it.

So the top right cable needs to go to the socket to the left. its a decorative brick wall so I can only assume the previous spark was going to remove the mortar to run the cable then re-mortar. If I can help it I don't want to run it surface.

Hope the poor drawing clears it up.

drill into the house in the corner( through plasterboard, then angle from socket inside to meet holes up then any patching up if you miss

 

[akwoody2]

drill into the house in the corner( through plasterboard, then angle from socket inside to meet holes up then any patching up if you miss

That wouldn't work, I need to get the cable coming out the corner of the wall (through the mortar) to the socket along the wall to the left. there's no plasterboard around. Looking at the regs there isn't anything stopping him going behind the mortar as its on an RCD. Shall I just go with what hes thinking?

 

[shanky887614]

That wouldn't work, I need to get the cable coming out the corner of the wall (through the mortar) to the socket along the wall to the left. there's no plasterboard around. Looking at the regs there isn't anything stopping him going behind the mortar as its on an RCD. Shall I just go with what hes thinking?

on the other side of the wall mate to existing, ignoring that socket for a moment

 

[akwoody2]

on the other side of the wall mate to existing, ignoring that socket for a moment

I see what you getting at now, could be an idea, some precise drilling but worth a go. I guess they are my only options

 

[telectrix]

think for a minute. the only reason you may not install cable in the brickwork joint is that the cement mortar will degrade T/E over time. so bung in some cable that will withstand the mortar.

 

[dingledong]

Yes I was told that, that the lime in the cement will damage the cable but talking to a helpline I was told that I was talking rubbish

 

[telectrix]

they ain't used lime in mortar for donkeys. and it would probably take over 30 years for modern cement to degrade T/E. bang it in, get paid, next job.

 

[shanky887614]

Yes I was told that, that the lime in the cement will damage the cable but talking to a helpline I was told that I was talking rubbish

they dont use lime mortor now thats not to say it isnt added sometimes

 

[Slowhand]

When I was an apprentice I was taught that it is unacceptable to take out mortar joints and bury cables in them. And so I would never do it, but I think it would be quite hard to find regulations that prevent it.

I agree. Too many people use the phrase " It complies with the regs " as an excuse for bad work practice.
" Dig out the mortar, bury the cable, get paid, move on " just doesn't do it for me.
The BGB is a standard we shouldn't fall below. There's no reason why we can't think about a problem and go the extra mile.

 

[atm84]

I wouldn't recommend bridging a cavity due to potential ingress of moisture. Not sure about how badly mortar would degrade the insulation but how about surface mounted galv conduit?

 

[shanky887614]

I wouldn't recommend bridging a cavity due to potential ingress of moisture. Not sure about how badly mortar would degrade the insulation but how about surface mounted galv conduit?

the cavity would be from inside the conservatory to inside the house.

not an external wall in other words

 

[akwoody2]

I agree. Too many people use the phrase " It complies with the regs " as an excuse for bad work practice.
" Dig out the mortar, bury the cable, get paid, move on " just doesn't do it for me.
The BGB is a standard we shouldn't fall below. There's no reason why we can't think about a problem and go the extra mile.

I agree with the standard, but if the "extra mile" could damage the brickwork and create a bad looking job then why do it? If you can take the mortar out and put the cable in, replacing the mortar after. As long as it complies and the workmanship is good, whats the issue?

 

[Slowhand]

I agree with the standard, but if the "extra mile" could damage the brickwork and create a bad looking job then why do it? If you can take the mortar out and put the cable in, replacing the mortar after. As long as it complies and the workmanship is good, whats the issue?

The extra mile doesn't mean damaging the brickwork it means thinking outside the box. I haven't seen this job so l can't offer advice. You mention damaging the brickwork, are you sure you can match the mortar up with the existing stuff? If not it'll stand out like a bulldogs whatsits.

 

[davesparks]

A carefully installed bit of MICC can blend in with brickwork acceptably

 

[akwoody2]

The extra mile doesn't mean damaging the brickwork it means thinking outside the box. I haven't seen this job so l can't offer advice. You mention damaging the brickwork, are you sure you can match the mortar up with the existing stuff? If not it'll stand out like a bulldogs whatsits.

its only about 4 inches of the mortar, i get your point about making it match. The easiest option is to put a bit of stone finish MT2 and surface mount a socket but its a crap job and look terrible considering the rest of the sockets will be flush.

 

[Engineer54]

I wouldn't recommend bridging a cavity due to potential ingress of moisture. Not sure about how badly mortar would degrade the insulation but how about surface mounted galv conduit?

You don't still believe in that old myth do you?? lol!!

So what do you think cavity insulation is going to do??

 

[Knobhead]

they ain't used lime in mortar for donkeys. and it would probably take over 30 years for modern cement to degrade T/E. bang it in, get paid, next job.

After 24 years in the lime and cement industry I can assure you, you are wrong. It’s added to many mortars. Another fact, the cement is made using a calcining process.

As to lime damaging PVC, I’ve never seen it on any of our plants even though the cables would be covered in lime. Lime being hygroscopic draws moisture in from the air causing it to set like concrete around cables.

 

[telectrix]

After 24 years in the lime and cement industry I can assure you, you are wrong. It’s added to many mortars. Another fact, the cement is made using a calcining process.

As to lime damaging PVC, I’ve never seen it on any of our plants even though the cables would be covered in lime. Lime being hygroscopic draws moisture in from the air causing it to set like concrete around cables.

i stand corrected, then, years ago, i was told that cement would degrade cable. must be another old myth.

 

[shanky887614]

i stand corrected, then, years ago, i was told that cement would degrade cable. must be another old myth.

i thought the myth was about lime plaster they were telling everyone not to put cables in.

im my opinion though it was more to protect the cable from the trowel rather than it being de gradeded

 

[Knobhead]

If quick lime is used mortar can become warm as it hydrates. Put too much in and it will boil so that could be where it tale has come from. Slaked lime is usually used.

 

[telectrix]

so then, tony. can you give any reason why he should not chase a short length of cable into the mortar as long as it's horizontal between 2 sockets, thus being in a safe zone.

 

[Knobhead]

Can’t think why it shouldn’t be done, but I hope the OP is good at pointing.

 

[telectrix]

if bob the builder can do it, how hard can it be?

 

[DPG]

You don't still believe in that old myth do you?? lol!!

So what do you think cavity insulation is going to do??

So using your theory then, it doesn't matter which you up you put cavity wall ties then - the drip point can go either way without any problem? Daz

 

[Wiresandthings]

Just chop into the mortar, and make good, you wouldn't think twice if was plastered wall?? Chopped in plaster or mortar its still chopped in and covered over with either plaster or cement, a small oval conduit may just fit into the gap for extra protection etc job done

 

[Knobhead]

So using your theory then, it doesn't matter which you up you put cavity wall ties then - the drip point can go either way without any problem? Daz

I think you’re getting a bit confused. We were talking of a cable running horizontally, running vertically then there is the problem of suspended weight and condensation running down the cable.

 

[DPG]

No confusion. eng doesnt seem to think moisture can track across a cable from one cavity leave to another. Its only the same principle as moisture tracking across a badly installed wall tie etc. Daz

 

[7029 dave]

I do like a cavity.:stooge_curly:

 

[Engineer54]

So using your theory then, it doesn't matter which you up you put cavity wall ties then - the drip point can go either way without any problem? Daz

So please explain the theory behind cavity wall insulation, which bridges both inner surfaces over the whole area of the wall, and negates what way up the cavity wall ties have been installed!!

Cables within cavity walls cause damp to internal walls is a myth and always has been.... Bad mortar jointing (normally on old properties) and unprotected/unsealed old and new penetrations are the major causes of damp, nothing to do with any form of cables being run in the cavities...

 

[DPG]

Building regs, document C:

Cavity external walls​

5.12​

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Any external cavity wall will meet therequirement if the outer leaf is separated from theinner leaf by a drained air space, or in any otherway which will prevent precipitation from beingcarried to the inner leaf.​

Technical solution​

5.13​

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The construction of a cavity external wallcould include:a. outer leaf masonry (bricks, blocks, stone ormanufactured stone); andb. cavity at least 50mm wide. The cavity is to bebridged only by wall ties, cavity trays providedto prevent moisture being carried to the innerleaf (see paragraph 5.15 for cavity insulation),and cavity barriers, firestops and cavityclosures, where appropriate; and​

c. inner leaf masonry or frame with lining.

 

[telectrix]

clear as mud. typical building reg.

 

[Engineer54]

(see paragraph 5.15 for cavity insulation),and cavity barriers, firestops and cavityclosures, where appropriate; andc. inner leaf masonry or frame with lining.

So what does paragraph 5.15 have to say then??

I don't think i've ever seen an installed wall cavity tie that hasn't been coated in fallen mortar from the progressing brick layers above, which make the middle drip arrangement basically null and void!! lol!! And yet, lo and behold, no sign of any damp on plastered internal walls!!!