Did you think that conduit is a thing of the past and electricians now use plastic conduit in place of steel?
Conduit is mainly used in industrial applications for running cables that need protection. Plastic conduit is the domain of the domestic installer, and rarely does it need to be bent other than to fit a crooked chased out wall.
How do you calculate pipe bend length?
Simple maths. If you thought an electrician had enough maths to contend with, here is some more to help, you get the right bend in your steel conduit.
It’s quite simple, and anyone can understand the rudimentary of pipe bending. Say you want a 90° bend in your conduit.
The bend represents ¼ of the full circumference, and the radius of the bend will be R which equates to the length of the bend =¼ x 2πR.
It can’t get much simpler than that.
What is the tool used to bend conduits?
Conduit bender. A conduit bender is used for bending steel pipes to run electrical cables inside for protection.
Conduit benders normally come on a tripod stand to allow you to get some purchase when bending the conduit.
Bending conduit is not for the faint-hearted and takes considerable strength spending on the conduit you are bending.
What is the most common type of conduit bend?
90° stub hub bend. The stub hub bend is made by bending two pieces of conduit at 90° or L shaped.
It’s a bend shared by electricians and plumbers and is often used to run conduit into steel junction boxes for termination.
It used conduits along walls horizontally and vertically and through ceilings.
Does conduit bend easily?
No, it’s tricky. Bending conduit for the beginner is a nightmare scenario, the conduit is tough, and you need to apply a lot of pressure while maintaining control to bend the conduit just the right amount to get the bend perfect.
Bending conduit takes skill and patience. With practice, you can get around most obstacles in an industrial setting.
You will need accurate measurement and enough pressure to make a perfect bend.
Why is my pipe bender kinking the pipe?
Material hardness, The main reason conduit buckles when bending is due to the hardness of the material. When conduit is being produced, it is a low-grade low-cost item, and as such, the precision in the manufacturing can be hit and miss.
As soon as you hit a hard spot, the conduit will kink or split if packed with sand. When the material is harder than it needs, it can’t compress on the inner side, which places additional stress on the conduit.
Where do you start conduit bending?
Look at the form for an arrow. The form is the profile that fits the conduit and effectively has the conduit radius.
You start bedding at the arrow, so you will need to have your conduit marked up with a sharpie to see all of the bending points required.
What is a saddle bend?
As it sounds. The saddle bend will straddle another fitment to the wall, so you bend a saddle shape into the conduit so you can clear the obstruction.
Is there an electrician’s guide to bending conduit?
Yes. It’s called Electricians Guide To Conduit Bending 3rd Third Edition. It contains all of the information that an electrician needs to be able to bend conduit for cable runs successfully.
It covers different types of conduits, such as aluminium and has a wealth of tips and knowledge imparted to make your life easier when bending a conduit.
The Electricians Guide To Conduit Bending 3rd Third Edition is available from Amazon.co.uk for around £30.
There is also the renewed American version of the Uglys conduit bending. The Uglys is slightly more affordable than the previous book at £14.43. It is available from Amazon.co.uk.
How is the conduit cut and threaded?
With lubricant. When cutting steel conduit, you will need to start with an open thread die and then tighten gradually as the trad cuts into the steel.
Use lubricant to keep the threads lubricated and make cutting easier by reducing friction.
Turn the die handle clockwise 3 to 4 rotations and then back off, clearing the swarf from the die.
You repeat the process until you have reached the desired length of thread needed.
Where is the conduit threaded, in the field?
Mainly on site. In some cases, you may decide that the bends are simple and the drawing is accurate, and you will tread the conduit back at the workshop.
But mainly, it is threaded on-site for ease. Plus, it’s easy to knock the thread end, and without the dies, it may be challenging to get the thread started.
Can steel conduit be used as CPC?
Yes. In the 18th Edition IEE BS7671, it states steel conduit is permitted to be used as a circuit protective conductor ‘A protective conductor may consist of one or more of the following:
- A metal conduit, metallic cable management system or other enclosure or electrically continuous support system for conductors.’
- For connecting to accessories such as switches and sockets, regulation 543.2.7 requires that the earthing terminal of each accessory shall be connected by a separate protective conductor incorporated into the associated box or other enclosure
- Metal back boxes for sockets and switches already include such a terminal, so this is just installing a short piece of green/yellow insulated copper wire from that terminal to the earth terminal on the switch or socket.
- Round conduit boxes have a 4mm threaded hole in the base. A ring crimp and 4mm screw can be used to attach a short piece of wire to connect to the accessory. This would typically be used in the case of ceiling lighting.
Do twin and earth need to be in conduit UK?
No. It will be fine if the cable is laid in a dry environment. If it needs mechanical damage protection, the cable can be placed in a conduit. Or trunking.