Earthing Arrangements Explained + Photo's

[tidyboiler]

I have that one and I have "2750 - Legend Of A Locomotive" which is a fictional story about an A3 Class Gresley Pacific named "Papyrus" that I've seen many times written by H.C. Webster. (I think I have some for diesel as well but let's not go there!)

Somehow, by fair means or foul, Tidyboiler managed to find a copy for me.

Actually, Tidyboiler stayed up until 3.45 am bidding against some Cockney for this book!!! I had to sell my other kidney and firstborn to pay for it! :love:

 

[zap]

Right you are, not to assume.
After obtaining some temporary seals from the DNO I looked inside the carrier and this is what I found.

Brush
30 Amp
60 LR
Certified
440V AC 4
BS88 - 1952
Class 3
Made in England

The print on the fuse had faded so there may be errors in the above info.

The DNO were contacted again and they're sending an engineer to address the issue.

Anyway, can anyone identify its breaking capacity?

 

[Richard Burns]

A BS88 fuse has a minimum breaking capacity of 50kA, unless it is a new BS88-3 when the breaking capacity will be 33kA.

 

[i=p/u]

I always put in 33kA... For main fuse.


i was working at a house yesterday and the earth was going into fuse , but not normaly where it goes to link at side... Would you still say YMCA

 

[Sparkyboxer]

Thanks for this thread little refresher

 

[Richard Burns]

I always put in 33kA... For main fuse.


i was working at a house yesterday and the earth was going into fuse , but not normaly where it goes to link at side... Would you still say YMCA

Probably still TNCS yes, so long as it is not one of the cast iron heads that have the earth tagged to the head

 

[Engineer54]

A BS88 fuse has a minimum breaking capacity of 50kA, unless it is a new BS88-3 when the breaking capacity will be 33kA.

Think you'll find that for most BS88 fuses it's 80KA, not 50KA....

 

[mrloy99]

If you have a neutral connected to an installations earth terminal (eg PME/TNC-S) then the incoming supply cables metallic sheath connection must be disconnected. Especially important where a supply cable is suppling both TN-S and TNC-S earthing arrangements!! eg, ....where the DNO cable is in the process of being PME'd....

emm? just wondering why?Does the sheath not need to be bonded too? I cant make out the writing on the service head,how do we know this presumably later conversion to TNC-S hasn't been done on the fly by mr diy sparky. I was thinking it could be left in place to be sure to be sure.

 

[mrloy99]

Just because you asked Archy

How it was explained to me at the EMEB collage.

Around each of the earth rods there will under earth fault conditions be a voltage gradient in the ground. In order for the MV and LV to be interconnected the LV earth electrode must be <2Ώ. Higher and the site is referred to by the DNO as hot and no direct MV→LV earth connection is allowed.
Therefore the LV earth has to be moved away from the MV equipment earth. This is to prevent a MV earth fault migrating to the LV system.

My drawing for OH supply

DNO drawing for ground mounted

I think these overhead earthing systems are being done away with due to copper theives leaving the rural customer without an earth

 

[Engineer54]

emm? just wondering why?Does the sheath not need to be bonded too? I cant make out the writing on the service head,how do we know this presumably later conversion to TNC-S hasn't been done on the fly by mr diy sparky. I was thinking it could be left in place to be sure to be sure.

Any exposed PILCS sheath to be wrapped in amalgamating tape. No problem mixing TT with TN, but it's not good Practice to mix Two Different types of TN systems....

Most DNO converted systems will be provided with a PME Warning Sticker. If in any doubt call the DNO to find out, just don't expect them to be quick in rushing round to check!! lol!!