Hi guys, I'm currently revising for my 2391 and kind of confused on the temperature factors for the Zs values
The BBB give Max Zs which are 100% values with a max operating temperature of 70c.
The OSG and GN3 give values to 80% which are when tested at ambient temp of 10c according to page 146...
Hi might be a stupid question but somone might have the answers.
TNS systems and TT where the Ze of the installation is a lot higher than a Ze <0.35 of a TNCS system, how do you comply max Zs of a MCCB in a panel board disconnection time of 5s? Most data manufacturers instruction give really...
Hi everyone,
Happy Friday!
Could someone please point me in the right direction, I’m after the Max Zs for a Bill Talisman TLF633 63A MCCB, I’ve looked in the BBB but to no avail on the Max Zs tables. I’ve also looked on our Cert software as they have a Max Zs app but the MCCB category doesn’t...
Good morning all.
Before I start I am not an electrician and am relatively new to this topic.
Current set up Axpert 5.5 Kw inverter, 7 x 420 watt panels in series and 2 x US 5000 Pylontech batteries paired (1 master 1 slave). System working fine will no issues.
I know this may have a simple...
Hi can anyone point me in the right direction
I’m looking for a copy of the max zs tables for fuses/mcbs etc from 18th Ed.
I’m awaiting my regs book to arrive and need to swat up, has anyone got a link I can print out thanks
I have 18 panels in 2 strings (37.8v open circuit voltage each) to be connected to a Fox H1 inverter. The manual says the below. Is the 600v open circuit voltage per string or for both strings combined?
H1 series inverters can be connected with 2-strings of PV modules. Please select suitable PV...
Hi
I'm looking at Table 7.1(i) in the On Site Guide. Max length of cable runs.
In some cases where there is no RCD protection the length is given as a number with a zs suffix. eg 47zs
The zs suffix means "limitted by Zs" the final circuit line-earth loop impedence.
In these cases is the...
Hi all, I have an assessment exam question that asks for the design value for a 32A 60898 MCB max Zs. By 'design' value is this the regs tabulated value (working temp) or the lower value 80% for testing in ambient?. With no other information the word design is throwing me as it seems like it...
I've seen some companies doing max demand calculations/reports on commercial properties and this would be useful for us to do. However we don't have anyone who is skilled/knows enough to do this. Although our team is very experienced this seems like a niche we don't have experience in. However I...
Hi new member here looking for a bit of advice.
I recently undertook a condition report of a building where the measured Zs at the distribution boards (board Zs) were above 80% of the max Zs value of the MCCBs in the panel board supplying them. In some cases it’s also above the 100% value.
I’m...
Hi all, Just wondering if anyone can shed some light on the max zs values in the OSG, they don’t seem to follow the 1.25 divisor stated in the note on page 126
For example BS 60898 circuit breaker, max zs at 70 degrees is 7.28, following the formula this should be 5.82 at 10 degrees which is...
Hello,
What would be the max Wattage immersion heater I could comfortably install on a dedicated 60A circuit?
Not DIY but trying to figure out some options before speaking with contractors.
Cheers!
An electrician once told me that I should always be careful not to exceed too much wattage on each circuit in a house by replacing light bulbs with brighter ones that are of higher wattage (e.g. don't replace all 60W bulbs with 75W or 100W bulbs).
However, with the newer CFL and LED replacement...
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