Discuss conduit and trunking impedances in the Commercial Electrical Advice area at ElectriciansForums.net

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gdr7671

Regular EF Member
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northampton
Hi everyone.

Can any professional here tell me where i can find the correct values of conduit or trunking
( resistance-reactance or impedance) m.Ohm per metre anywhere. Every where i have looked
IET-ECA-NICEIC give different values. One of them must be correct (i assume). I can't find a British manufacturer to find the information; you have all guessed MADE IN CHINA, so no help there!!
Any info would be a great help.
Thanks in anticipation.
 

telectrix

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the impedances of conduit and trunking will depend on the csa of the metal. it's not something you can put a value to as different manufacturers stuff will differ.
 
E

Engineer54

the impedances of conduit and trunking will depend on the csa of the metal. it's not something you can put a value to as different manufacturers stuff will differ.
If all made to a British Standard, i can't see how there could be that much difference to be honest. The metal make up may have some effect on resistance values etc. I would imagine wall thickness (CSA) would be covered within th BS specification...
 

johnboy6083

Band Member
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2,946
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heavy guage conduit resistance (miliohm/m) reactance (miliohm/m)
16mm 3.3 3.3
20mm 2.4 2.4
25mm 1.6 1.6
32mm 1.4 1.4

if the fault current is less than 100A, then the above values should be doubled.

the above valuies are indepenant of temperature, and can be used for design and verification.


all of the above taken from table F.11 of the Electricians Design Guide
 
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gdr7671

Regular EF Member
Messages
74
Location
northampton
Thank you for your help. I have had such different values from different sources. I will use these from now on. Thanks again.
 

johnboy6083

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im sorry about the fromatting of my post, i had ensured that the values were underneath the applicable columns, but the forum software altered it!
 
E

Engineer54

heavy guage conduit resistance (miliohm/m) reactance (miliohm/m)
16mm 3.3 3.3
Do you still use metal 16mm conduit in the UK, either in standard or heavy gage form??

I remember alarm boys using 1/2''/16mm light gage conduit, but haven't seen any used
for general building services or domestic work, since in my early training days... lol!!

They use a lot of 16mm PVC conduit in Europe (and certainly Cyprus) for embedded domestic lighting installations
and the like....
 

telectrix

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never seen 16tmm conduit in 40 years. used to use 1/2" ally tube for alarms though. in that situation, it was only there for mechanical protection.
 
E

Engineer54

never seen 16tmm conduit in 40 years. used to use 1/2" ally tube for alarms though. in that situation, it was only there for mechanical protection.
That was my point Tel... They must still be making the stuff to have a figure relating to this sized conduit. Unless it's by calculation only?? ...lol!!!

To be honest, the only 1/2'' conduit i've actually seen, was the old light gage/split seam conduit. I dont think they made it in standard or heavy gage in my time. Maybe before, but as i say i've never seen anything in this size, apart from light gage/split seam form....
 
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