doubting the world is flat.

thekingiam · May 16, 2012

going to start doing a rewire and going to use it to join elecsa, i have started questioning even the most basic things trying to get it right.
looking at an old electrical book i have and it states back boxes need to be secured with round head screws also remember the subject comming up when i was doing 2391 , the thing is every job i have been on they never have,and i thought it was the other way around for some reason?
( this is embarasing for me to ask so please be kind )

Dave 85 · May 16, 2012

I have to say, I never saw a screw that didn't have a round head, not really sure what you are on about tbh...

ipf · May 17, 2012

Blackjaps...used to use them by the thousand for pyro clips.

thekingiam · May 17, 2012

i mean pan head

ipf · May 17, 2012

Round head, pan head, countersunk....all different.

thekingiam · May 17, 2012

ok is there a regulation stating certain screws not to be used?

Strima · May 17, 2012

As long as there's no chance of the cable chaffing on the screw you could pretty much use anything. Pike nuts shouldn't really be considered though as you'll never get the plate on unless you use deep backboxes.

[ElectriciansForums.net] doubting the world is flat.

thekingiam · May 17, 2012

thankyou

MarkieSparkie · May 17, 2012

thekingiam said:
ok is there a regulation stating certain screws not to be used?

No there are no regulations requiring certain screws per se, however the 'catch all' BS7671:2008, Amt 1:2011, 134.1.1 applies Good workmanship by competent persons or persons under supervision and proper materials shall be used in the erection of the electrical installation. Electrical equipment installed in accordance with the instructions provided by the manufacturer of the equipment.
It's good practice to fix back boxes with pan head screws to prevent snagging of the cable or conductor insulation, however one sees few examples of this good practice when inspecting these days. Most often we see the bodge of countersunk screws being used, with or without a covering of insulation tape or even on occasion Duck tape. The use of slotted fixing screws should be avoided as their slots often burr badly, particularly when power driven, causing extremely sharp edges which easily shred insulation.

telectrix · May 17, 2012

what's wrong with clout nails ? nice flat heads.

:81:

Rockingit · May 17, 2012

A Box of 100 panhead self-tap 8 x 1-1/4" from a popular screw fix company set you back about £5.
A Box of 100 4 x 50 woodscrews from same place - £3.

Go figure!

I very much doubt that the assessor is going to be disturbed by choice of fixing screw, so long as the box is secure and the cable insulation not likely to get damaged. TBH, I doubt it'll even get looked at - just make sure you put oversleeve on all your strappers and light switches, as they WILL notice that!

firemanowl · May 17, 2012

Countersunk screws grip with the taper so when using them to secure backboxes there is only the thickness of the metal in the boxes that is in contact with the taper of the screw. Whereas with panhead screws there is more surface area of the screw in contact with the backboxes. I got asked that question on one of my practical exams at college, where should you use different types of fixings and why. Most people use countersunk because they are quick and easy, can't remember ever seeing any work loose though.

thekingiam · May 17, 2012

ok cheap and cheerfull it is then, i was sure it came up when i was doing 2391.
i am used to working for companies that use countersunk.

cymroaur · May 17, 2012

According to my local builder, everybody now uses sticks like s**t to mount them.

doubting the world is flat.

thekingiam

Dave 85

ipf

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thekingiam

ipf

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thekingiam

Strima

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thekingiam

MarkieSparkie

telectrix

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Rockingit

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firemanowl

thekingiam

cymroaur

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