Awkward customer, some questions: (back boxes)

[ProDave]

I'm quoting for a downstairs rewire in a property water damaged by a burst pipe.

The trouble is, everything has been specified by an architect, and he wants everything exactly as his specification, and having spoken to him, he won't deviate.

My particular problem is he has specified metal back boxes.

But the refurb makes that awkward. Basically it's an old stone building, that's been timber studded inside. Insulation is going back between the studs, then there's a vapour barrier over those, that must not be penetrated. It's then being counter battened (25mm horizontal battens) and plasterboarded.

There's no room to fit dwangs behind the boxes to fix them properly. (noggins for you down south ).

The architect says "just put the metal boxes next to the counter battens and fix through the side"

I pointed out that is at best a bodge that I do when there's no alternative, but I don't want to do that as a matter of course.

He won't entertain the idea of plastic snap in boxes. Not because he doesn't think they work, but because he hates PVC, says it's not sustainable, bad for the environment etc (oh no an eco warier)

So does anyone make snap in plasterboard metal back boxes so I can do the job properly and still meet his specifications?

Second question. To prevent this happening again, they want several heaters all switched from one frost thermostat. Easy enough.

But they want two of the heaters to be able to be manually turned on as well.

so I'm thinking a contactor, or contactors to switch the heaters. The only thing I think is the manually switched heaters must be on their own individual contacts of the contactor, to allow that to be bypassed manually.

All the rest of the unswitched heaters can share one contact (subject to rating obviously)

 

[sellers]

Only option I can think of with using knockout boxes is to get the joiner on site to screw 2 battens either side of your hole in the plasterboard and fix to either side then. TBH plastic backboxes don't rust and last forever.

 

[Andy™]

for the heaters, use a 2 way switch for manual control - common feeds heater, L1 is sw.live from stat, and L2 is permanent live. that way, the switch is either 'on' or 'auto'. obviously all lives from the same circuit

 

[Apache]

TLC do the fire rated metal back boxes Dry Lining Accessory Boxes

 

[Lee321]

good solution andy depending on heater ratings

---------- Post Auto-Merged at 13:20 ---------- Previous post was made at 13:19 ----------

patch that was knockout if you pardon the pun

 

[ktguk]

why do people tend to go mad with barn's e.g. odd requests, green everything. as if they werent awkward enough

 

[ProDave]

for the heaters' date=' use a 2 way switch for manual control - common feeds heater, L1 is sw.live from stat, and L2 is permanent live. that way, the switch is either 'on' or 'auto'. obviously all lives from the same circuit[/quote']The heaters that need manual control are 120W and 240W only, so the 2 way switch idea works well, a 10A sp2w switch will be fine for that.

TLC do the fire rated metal back boxes Dry Lining Accessory Boxes

I like that solution. The customer gets his metal boxes, and I'm happy they are designed for a dry lined plasterboard wall, so no faffing about trying to get dwangs in the right place or screwing through the sides. He even gets fire rated boxes into the bargain.

Thanks for your help, I think that should keep the awkward customer happy.

 

[Andy™]

Thanks for your help, I think that should keep the awkward customer happy.

unlikely. there will always be something else

 

[Sidewinder]

I trust the Architect is signing the design section of the EIC and he is competent to do so then?....

 

[PC Electrics]

AFAIK plastic back boxes are made of PP (polypropylene), possibly PC (polycarbonate) not PVC. Not least because PVC is expensive compared to PP or PC.

Those metal boxes look very good, but they certainly are pricey!

 

[kerching]

Appleby SB603.......adapters for fitting to steel backboxes to enable fitting in plasterboard walls.. Never used them meself, though but............... :coat

 

[Evans Electric]

And probably cost more in natural resourses to produce , why don't parts like that artichoke keep their noses out of the electrics .

I had one once who wanted us to rewire a house using steel conduit . Said we could drill a row of holes through the joists and feed a length of steel tube through!!!!

The reason was , this house was on the grounds of a hospital and used as offices, the problem for them was the hospital standard elect. specification did not include for twin and earth wiring , only conduit, MICC, trunking , SWA .

Took some effort to convince him that you can't thread steel conduit through holes in joists. So he had it installed by slotting out the top of the joists and miles of floorboard removed.

Bloody ridiculas TBH, took forever and cost a fortune.

 

[steptoe]

eureka,

flexible steel conduit that sets solid with the addition of some galv paint,

this time next year Deke.........

 

[kerching]

Ah, the good ole Architect.

Did you know that the term 'Architect' is derived from the Greek words 'Arch' meaning Bloke and 'itect' from the verb ictos meaning ' to know s0d all '.

Another example is Archaeologist.... 'Arch' meaning Bloke and 'aeologist' from the verb aeologos meaning 'to guess wildly'... :coat

 

[jameseye12]

So if the architect doesn't like PVC does that mean he's specified the cable to be VIR or MICC then?

 

[steptoe]

I like the idea of VIR,

but would lead sheath be a better choice for longivety.?

less copper required too, you can just clamp the sheath for earth......

 

[NozSpark]

And I thought that concrete was the most environmentally unfriendly building material?

 

[jameseye12]

And I thought that Architects didn't design electrical installations? The World is Full of Surprises

 

[Sidewinder]

james,

They obviously don't! ROTFWL

 

[jameseye12]

I though that was the case in this particulary thread. Or maybe I mis read the OP.