meter tails

[IQ Electrical]

Re: School Science block

We have on discussion now agreed the following specification but are still awaiting a confirmation from relevent bodys.

2 x Parallel 95mm on each phase
2 x Parallel 95mm on Neutral

From Reading table 54.8 bs 7671(20011)
The Main Earth & the bonding are both 50mm or is there a strange PME ruling increasing my main earth.

Unless any of you clever bods out there disagree??


We are already applying some diversity as we have 11 hobs, 11 ovens + sockets for kettles etc + ac & lighting maximum load could be 90+ amps per phase

We have supplied them from our panel board with 80amps per phase 80A tp mccb supplying a 25mm swa sub main & a 100amp 12tp way distboard. So hope they dont try everything at once.

That's exactly why I asked in post#3.

Your 50mm earth and main protective bonding are sized from the SUPPLIERS neutral on a PME system and 50mm is the largest given in table 54.8 (although these are minimum sizes).

 

[UKMeterman]

Get the science teachers to turn on what they would expect to have on worst case and get in there with a current clamp.

More interesteing for the students and the school, fit some Crompton Instruments Tegra meters, these can be remote read over the network, measure W, VAR and VAR.

 

[IQ Electrical]

More interesteing for the students and the school, fit some Crompton Instruments Tegra meters, these can be remote read over the network, measure W, VAR and VAR.

Lol, they're there to learn how to make a bacon butty, I don't fancy your chances of teaching them AC power theory!

 

[UKMeterman]

True,
but it allows the students to see how much power they are useing as we are supposed to be going green and educating the students.

 

[stott]

Re: School Science block

What size Main Earth & Bonding would you recommed.

 

[stott]

Some in this thread said we should clamp with everything on?

Would love to but domestic Science is at present being installed in a room that was only a basic classroom
Thus the installation of 12way TP board
The rest of the building labs etc. have changed dramatically from last year due to 2 schools combining

So come September 4[SUP]th[/SUP] we need it right on a theoretical load

 

[malcolmsanford]

Your bonding I would take from table 54.8 reg 544.1.1 so for your 2 x 95mm in parallel which makes 190mm so 50mm Main Protective bonding conductor, but as this is just a room within the installation is bonding needed or is this an upgrade of the main supply?

Again you main earthing conductor for PME is taken from Table 54.8 and it should be measured against the SUPPLIERS INCOMING NEUTRAL, but as your tails are 190mm I would safely say the suppliers will be same bigger. So theoretically it could be 50mm, but I would be inclined to do the Adiabatic equation in reg 543.1.3 for such a large installation.

 

[stott]

Finally got an answer from Network Power
185mm tails with 95mm earth & 50mm bonding

So if that’s what they want that’s what they get
I’m just pleased to get a definitive answer.

 

[IQ Electrical]

Finally got an answer from Network Power
185mm tails with 95mm earth & 50mm bonding

So if that’s what they want that’s what they get
I’m just pleased to get a definitive answer.

A result!