Hi Guys,
in an installation with one main Distribution board and several submain-DBs, do when you measure Zdb on a submain-DB incomer? and do we need to verify the Zdb value with the upstream protection device?( for example, a 250A, MCCB on the MDB outgoing). If yes, how can I get the max Zs...
Hi All,
Thank you for welcoming to this forums
I just want to clarify that the Value I need to enter 100% or 80% in the last column "Maximum Zs Permitted by BS7671"
is it 80% from the table 41.3 from 18th Edition Regs - Page 62 or the value from Pocket Guide 18
Thank you
Loges
Morning all,
I'm currently finishing off my Lvl 3 C+G and I just need to finish off my design spreadsheet then I'll have completed it. I've one last column to fill in "Max Zs @80%" the design is based on a hotel using a TN-C-S supply. I'm just wanting to know where I can find this information...
Hi all,
Why is there no max Zs value for a 45A type B breaker in table 41.3 of 18th edition? What value should be used as max value on schedule of test results?
Cheers.
I have little knowledge of PV.
When working on circuits supplied by a domestic CU, is it fine to just have the main switch off in the CU or should you be isolating the PV as well?
The stickers all over the CU's in this example all say to disconnect both supplies.
Hello All,
Iv been asked to pick up the remedials on someone else's EICR that was done last year on a school for Deaf Children. One of the items listed on the report is the conductors leading to the sub mains from the main panel are undersized. I popped the cover off to have a look and sure...
I'm just hoping I can cross reference my knowledge or be corrected by someone on a quick query. It's a test question I'm doing but I'm querying the answer I've been given.
I want to find the Max permitted Zs on a 3036 45A fuse. I was under the impression that I should reference table 41.2 in...
Seen a couple of threads on diversity and excessive max loads recently.
Just had a design from a clients for their house. Applied diversity is 196A.
Having 2 9kW showers install, A 4kW instant water heater, a cinema room, ring main per floor, lighting circuit per floor and ring main for...
This relates to one of those old 60A Wylex Fuse boxes that has been upgraded with MCBs - I know it would be a very good idea to upgrade, but the question is, how does the "Max 60A" rating moulded on the box apply? The main fuse is 60A and the load after diversity calcs is 89A.
I am aware that...
Hi,
Looking at a potential job. Agricultural buildings being divided into 10 mixed use units of around 1000 sq ft each.
Present supply is a 100A TPN incomer.
Future use of units is unknown at this stage, but planning is for B1 B2 so uses could be anything from a warehouse with a bit of lighting...
I am filling out test sheets and have a merlin gerin D32 C60 HD double.pole mcb. The rating on the mcb says 415V feeding 2 feeds to a canalis busbar.
BS7671 States max zs for D32 0.4 secs is 0.34. Is this just for single pole MCB?
I have also check my max zs value
from manufacture stating...
Can anyone give me some clarification on the following.
I am installing some Osram Planon Plus led light panels into a temporary building and have been told the transformers need to housed in an enclosure as they do not have the correct markings for BS7671 "max surface temperature under fault...
Just processing an EICR and noticed a couple of final circuits measured Zs values (fed from a sub distribution board) slightly exceed the Max permitted Zs values for the OCPDs that protect them.
Obviously I will note this as a design flaw in the observations, but I just wondered, from the...
Hi we are using allen Bradley 1489 and 1492 range of circuit breakers, and I cant find the max zs values on any of the data sheets, does anyone have a list of them?
Many thanks
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