chasing in oval conduits and filling in chases advice please

[Guest112]

Hi guys, before starting this thread I have searched old threads on this site and had no luck finding a good one. I started a thread a few weeks a go my house rewire and now im after a bit of advice on filling chases.

I rarely do domestic electrical work so have barely touched on chasing, the jobs that i have done/been on in the past involving chases have been done by labourers.

im going to chase in oval conduits and would appreciate advice on how you guys fix the conduits in before filling, a colleague of mine says he pins in the conduits using nails to hold the conduit before filling with a sandy concrete mix leaving 3mm for skimming after. Does this sound good?

as far as chasing the drops im either going to borrow a wall chaser if i can or use a grinder with diamond disks and scutch out the center.

to cut out the boxes im going to use a grinder to cut the square and chisel out the centers by hand after fixing the metal backboxes and running in the conduits i plan to fill the chases and cuts with a concrete mix with 1 part sand to 3 parts concrete and leave the 3mm gap for skimming over.

a few things im wonderingn are first of all is there anything wrong with anything ive said and also what cables will fit down a flat 20mm conduit? im guessing i need 25mm drops for the 2 2.5mm twins for the rings

thanks in advance guys

 

[Lighthouse Phil]

Steel nails for fixing the conduit.

 

[cjp1]

Big headed galvanised clout nails fixed into the mortar joints in the brick or block work are suitable for holding the conduit in place.
I would use bonding instead of sand and cement to bulk fill the chases then multi finish or the like for the final finishing depending if your patching up the walls or skimming over a complete wall.
I also pva the chases before bonding 1st with a weak mix of pva & water then once dried go over again with a stronger pva & water mix (3 parts pva to 1 part water) let it go sticky or dry then bonding over the top

 

[mackers]

crampets are easier to use than nails

 

[telectrix]

use the proper clamps for the egatube. nails are for wood butchers who don't know how to use a screwdriver.

 

[dingledong]

i know how to use a screwdriver its something you hit with a hammer isn't it

 

[timbobelfast]

Agree with the use of cramped. To fill in, soak the track first and use a mix of bonding with a small amount of finish.

 

[Guest112]

great advice so far guys really appreciate it after a bit of further researching im to understand that bonding can actually absorb moisture so in bathrooms so better to use a bit of cement instead but seeing as ill probably have to buy a bag of cement anyway i might aswell use that up ( I have other jobs i need it for also) ,

ill pvc the chases and the pipe? to help it stick and fill like i said leaving a gap of about 3mm and use finishing plaster? or multi finish? seems easy enough in theory

ive noticed that everyone seems to use their own method some using bonding, some sandy cement, some using onecoat plaster etc i was expecting there to beone strict method but it seems its an each to their own kind of thing,

again anymore advice would be greatly appreciated

 

[ratboymark]

hello one tip you might find usefull is score a few chases into the wall with your grinder where your boxes are going to make chasing that little bit eaiser i often find this helps, but be warned its very dusty using a grinder and ive never used one in a lived in house hope this helps and good luck

 

[Guest112]

cheers mate, trying my best to borrow a chaser, grinders my last option but its my house so ill be the one putting up with the dust but id rather not lol yes my mate recommended cutting accros vetically and horizontally in each backbox and he reckons it helps a lot

 

[the pict]

Not to hi-jack the thread but, are you required to use conduit,seems like all the old cable I'v hauled out of walls is just plastered over and held in by metal wrap round clips and nailed in,
Pict

 

[Guest112]

no isnt required i could use capping or just skim over the cables directly, but i dont particularly like using capping as it jams the cable to the wall and if i just skim over the cables if a fault develops ill have to smash the plaster off to replace the cable, not that i expect any faults but you never know,

im mainly using conduits because being a spark and seeing as its my house i thought id go the extra mile and seeing as the capping id need is as wide as the chase needed for the conduits just a bit deeper i might aswell,

im also not that experienced domestically and having used capping id like to use the egatube to compare methods for the future when i plan jobs etc,

AND... im not sure how long i will be living in the house so future proofing aswell mate

 

[the pict]

Hi yes fair comment, and if it had allways be done like you intend it would make rewires a doddle, and if you can you post a few pics as the job progresses, may well be a usefull guide.
Pict

 

[Guest112]

yes my plan is to record the rewire and take pictures step by step of the whole rewire explaining calculations and reasons for doing things etc im going to speak to one of the mods or admin to see if they can help me about it considering its my house and i have all the time in the world to do it it gives me a chance to take pics and whatnot ect

 

[Ponty Massive]

I always use oval conduits when rewiring. Screwfix sell oval conduit clips. Type in Oval conduit clips in the screwfix search box.

I keep my chaser set at the correct width and depth, makes life a lot easier !!

 

[Guest112]

ye ive seen them mate was debating getting them or not my only worry was they might bring the conduit off the wall by a few mm so would have to chase deeper but as ive said im completely new to chasing and oval conduits like

(i hope i get a chaser lol going to be a nightmare with a grinder)

also can anyone tell me how they chase up to the ceiling because the chaser can only reach so far any tricks at the top or just good old fashioned hammer and chiseling??

cheers guys advice has been great so far

 

[Ponty Massive]

Peter

I'd use a chaser withdust extraction rather than a grinder. A LOT less mess and both chases are spot on. Use the chaser as high as possible then scutch chisel on the end of an SDS drill (hammer) to chase the tops.

Also for back boxes, I tend to mark the box on the wall, use some insulation tape and mark the correct depth of the back box on a drill bit, drill a load of holes around the box to the correct depth, then again scutch chisel on SDS to knock it out. A bit of practice and no need to fill around the box..

 

[VoltzElectrical]

Peter

I'd use a chaser withdust extraction rather than a grinder. A LOT less mess and both chases are spot on. Use the chaser as high as possible then scutch chisel on the end of an SDS drill (hammer) to chase the tops.

Also for back boxes, I tend to mark the box on the wall, use some insulation tape and mark the correct depth of the back box on a drill bit, drill a load of holes around the box to the correct depth, then again scutch chisel on SDS to knock it out. A bit of practice and no need to fill around the box..

I use this method called 'stitch drilling' for lots of masonry applications. Works a dream. For the amount of work here though, a trip to speedy hire or the like, and a day's hire of a wall chaser and extract unit every time.

 

[Guest112]

thanks guys great advice so your saying literally using a say 5-6 mm bit drill the outline of the box and then knock out the center and then your pretty much spot on size wise

i was going to cut the square and fil the lines where they go beyond the box size for the depth but by the sounds of it my idea very messy using a drill MUCH tidier and you get your depth spot on, cheers guys again very good advice thank you

 

[MarkieSparkie]

Hi Peter,
There is an alternative to purchasing/hiring a chaser. Grinder guards with extraction port and depth stop, with a "Henry" vacuum cleaner make a cheap set-up which will minimise the dust, but it's still going to messy like all chasing. This is the kit I used for 2 years after getting started and still use this type of set up for some specialist chases.
You will only need 4.5" angle grinder with a diamond blade. 9" angle grinders are over-kill and extremely difficult to use for chasing due to the weight of the tool and the gyroscopic effect.
Bosch do a guards for most of their models, with extraction port and depth gauge, see link below:
Angle Grinder Dust Extraction Guards | Miles Tool & Machinery Centre