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Discuss Drilling holes in new joist for cabling in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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J

jezza

Can someone please help. I am running some cables in our new exstension. The joist are approx 4.2m long, am i right in thinking that i have to drill my holes between 0.25m and 1.68m on either side. Many Thanks
 

IQ Electrical

Electrician's Arms
Holes should be:

No greater diameter than 0.25 times the joist depth

Drilled at the neutral axis

Not less than 3 diameters (center to center) apart

Located between 0.25 and 0.4 times the span from the support
 

Dunc

Regular EF Member
Holes should be:

No greater diameter than 0.25 times the joist depth

Drilled at the neutral axis

Not less than 3 diameters (center to center) apart

Located between 0.25 and 0.4 times the span from the support
I always thought it was 5 diameters apart. Learn something new every day!

Here's a good reference document i just found. LINK
 
C

claret73

And this is all good & applicable if LABC Do not think any other Trades will be driiling for their services...On a new build & have been drilling for socket & lighting drops at the required measurements. However, domestic Sprinkler system & plumbing have all gone in & neither of those are within parameters...
 

IQ Electrical

Electrician's Arms
And this is all good & applicable if LABC Do not think any other Trades will be driiling for their services...On a new build & have been drilling for socket & lighting drops at the required measurements. However, domestic Sprinkler system & plumbing have all gone in & neither of those are within parameters...
Are you in Wales?

Don't see many domestic sprinkler systems going in but I recall it being a requirement on Welsh new builds?
 

roukel01

Electrician's Arms
its true its true... you talk to any other trade about building regs "Safe Zones" and where we should drill holes for cables and they look at us with a blank expression!!!!
 
E

Engineer54

Never had any of the baloney in my day...lol!! The only stipulations i remember was notching wasn't allowed and that auger holes to be a maximum of 1 1/4'', for cable runs. They, to be a minimum of 2'' from top of joist to top of auger hole. ...That was about it!! lol!!!
 
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C

claret73

Are you in Wales?

Don't see many domestic sprinkler systems going in but I recall it being a requirement on Welsh new builds?
Nope. This is a UK Development. Fire Service took a risk assessment & deemed that the fire could spread entrapping the engine, so sprinkler systems installed. The lad I spoke to, said it was heading towards being Mandatory in UK at some point...(I'm glad it's in, especially with those downlighters I've had to put in...)
 

JUD

Electrician's Arms
Can someone please help. I am running some cables in our new exstension. The joist are approx 4.2m long, am i right in thinking that i have to drill my holes between 0.25m and 1.68m on either side. Many Thanks
Holes should be:

No greater diameter than 0.25 times the joist depth

Drilled at the neutral axis

Not less than 3 diameters (center to center) apart

Located between 0.25 and 0.4 times the span from the support
That would be between 1.05m and 1.68m.

Everything else as IQ has already said.

Don't know the depth of the joists but something else to think about is that if the cables aren't mechanically protected then they need to be a minimum of 50mm beneath the floor or above the ceiling to avoid damage by screws/nails etc.
 

Des 56

Forum Mentor
Electrician's Arms
Trainee Access
DIY
Sprinklers are not required on new build in Wales
The Welsh government passed the idea but it did not have the power to implement it, 2 years ago at least

It will have the power over building regulations later this year, I believe, and sprinklers are still very much on the table for very quick implementation
It is also believed that other parts of the UK will follow very soon after

I would take a guess that by next summer,all new builds in Wales will have this requirement

Perhaps its time for a sprinkler course
 

telectrix

Scouser and Proud.
Respected Member
Forum Mentor
Electrician's Arms
CCTV / Alarms
Solar Guru
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Never had any of the baloney in my day...lol!! The only stipulations i remember was notching wasn't allowed and that auger holes to be a maximum of 1 1/4'', for cable runs. They, to be a minimum of 2'' from top of joist to top of auger hole. ...That was about it!! lol!!!
that's when joists were real tree wood, and not as flimsy as the buildres could get away with.
 
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