VB breakers

[musicspark]

Be careful on pricing this job if they have a standard split load cu on TT supply that is not right. Unless the external ze is unusually low which generally it will not be on TT you may come up against all sorts of problems. It makes me wonder who installed the cu.Batty

Can you help me a little more here on the pitfalls of TT. The CU is not split load but what if it were?

 

[Lurch]

So it's a non split load with a 100A main switch and also a 30mA RCD? Sounds odd, are you sure it's not split load?

 

[batty]

Can you help me a little more here on the pitfalls of TT. The CU is not split load but what if it were?

Sorry I thought you said it had a main switch and 63 amp RCD. So is it a dual RCD board?

 

[musicspark]

OK. It could be slit load.

Allow me to elaborate on this one. A mate of mine told me he was going borrow an abrasive wheel tile cutter form a friend who "might need some sparky work done". Could I go with him, as it was a bit off the beaten track and he might need a hand, and I could find out what needed done while I was there

We are talking a mile from the road, we nearly got stuck in the snow on the way up and had to walk the last 300yards (-11 degrees and 2ft deep where the JCB hadn't been).

He showed me around the Garage and where he wanted to put the the CU for it. By the time we got back into the house I had snow up to my knees and his wife had made me a coffee and wanted to discuss a new cooker point with me.

By this time, my mate was starting to worry about the van which was abandoned at the other end of the field so I decided not to clamber on top of his wifes worktop to take the cover off the board (above the wall cupboards)

for closer inspection.

I have not priced the job and I told the guy I would come back and make a better assessment when the weather improved

We went home.

So I suppose I should rephrase; I don't think it is split load

 

[batty]

Take some piccies when you go back.

 

[Evans Electric]

ELCBs are voltage operated earth leakage circuit breakers as opposed to RCDs which are current operated. ELCBs are usually fairly large, brown , 30 A- 45A- 60 A rated often with a yellow test button . Their use is now discouraged and should be swopped for an RCD as they often don't work.

I don't understand the ref; to Spidey tingling I,m afraid.

Volex MCBs are , as far as I know, idendtical to Crabtree if you can't find a stockist.

Deke

 

[musicspark]

main sw at one end rcd at other no labels to say rcd protected on specific

breakers and no logical place for split to be.

I would have to remove the cover to find out exactly what was what.

I am aware of the fact that in the case of a high Zs (as is usual with TT) there would have to be rcd protection.

Also, the CU would often have a 100 or 300mA rcd as main switch.

My first impression was that someone had installed a CU with 100A main sw and

installed the rcd as an afterthought to comply with regs

 

[batty]

main sw at one end rcd at other no labels to say rcd protected on specificbreakers and no logical place for split to be.

I would have to remove the cover to find out exactly what was what.

I am aware of the fact that in the case of a high Zs (as is usual with TT) there would have to be rcd protection.

Also, the CU would often have a 100 or 300mA rcd as main switch.

My first impression was that someone had installed a CU with 100A main sw and

installed the rcd as an afterthought to comply with regs

I think you will find that is split load the split will be roughly in the middle.

You will need to do loop test before you price this job. Where is meter?

 

[Lurch]

There's a few boards that have MS at one end and RCD at the other. The split will be somewhere between the 2.

 

[batty]

There's a few boards that have MS at one end and RCD at the other. The split will be somewhere between the 2.

I said that.

 

[Lurch]

I said that.

So you did. Well done.

 

[musicspark]

I think you will find that is split load the split will be roughly in the middle.You will need to do loop test before you price this job. Where is meter?

meter is next to CU

I did also tell the guy I would have to do some tests before I would know what was was needed.

 

[musicspark]

there is space to add another rcd + two spare ways

 

[batty]

Maybe there is an Rcd or voltage operated trip before cu.

 

[kme]

But he did say there was no labelling mate - suggests job wasn`t carried out properly in the first place........

If you`ve got space for another RCD, you`d be best off fitting one next to the main switch, with a, b, and c circuits on it, then the existing RCD, with x, y and z circuits. As has been said, you need to do some testing, and a visual inside that CU before you go any further. Don`t forget to verify MBC`s

KME

 

[musicspark]

Maybe there is an Rcd or voltage operated trip before cu.

I'll keep you posted when I return.

I am in no hurry in this weather.

Would I be right in thinking that if loop impedance readings are high, that 30mA rcd protection on all circuits (provided that there is a high enough fault current to operate at less than .2s @

) would be compliant with regs?

 

[musicspark]

But he did say there was no labelling mate - suggests job wasn`t carried out properly in the first place........If you`ve got space for another RCD, you`d be best off fitting one next to the main switch, with a, b, and c circuits on it, then the existing RCD, with x, y and z circuits. As has been said, you need to do some testing, and a visual inside that CU before you go any further. Don`t forget to verify MBC`s

KME

thanks for that - It's what I had in mind (when the snow melts a bit)

 

[kme]

Would I be right in thinking that if loop impedance readings are high, that 30mA rcd protection on all circuits (provided that there is a high enough fault current to operate at less than .2s @ x five delta n ) would be compliant with regs?

NO. As long as you`ve got 1666 ohms on your TT (although >200 is unstable, and NIC prefer <100 ohm), your RCD must trip, atx five delta n, within 40mS, NOT 200mS

 

[SPECIAL LOCATION]

Hello all, I hope we are all coping with the weather.I have been asked to fit a supply to a Garage on a tt supply when I looked to see if there was a spare way in the CU I noticed that it was a Volex with 100A main switch and 63A 30mA rcd

However, the breakers are all labeled VB6, VB32, etc. Can someone tell me if the V in VB stands for Volex or Voltage

Also, if these are voltage breakers would I need to replace the CU?

Just the standard identification for all Volex MCB's

http://www.screwfix.com/search.do;jsessionid=EIACBZZUG043OCSTHZOCFFY?_dyncharset=UTF-8&fh_search=VOLEX+MCB&searchbutton.x=16&searchbutton.y=10

 

[SPECIAL LOCATION]

blimey!

this threads got long......

maybe should of read it all before posting!Blushing