Earth bonding question.

yoshytoshy

Hello ,recently I was working in a house that needed it's earth cable changed from 6sq to 10sq ,to qualify for the seai grant.
My uncle who's a reci electrician told me that because the cable run was less than ten meters ,there wasn't any need to have 10sq.

Was he telling porkies ?

2011

I don't have enough information to answer fully.

However most bonding/earthing in a house is done with a 10 sq. mm cable. This would include the gas pipe, hot press and earth rod. Some supplementary bonding is done with a 2.5 as far as I can remember.

I have not carried out any work in domestic installations in years.

A 6 sq. mm cable would be used as a protective conductor for a circuit with a 10 sq. phase conductor.

I hope this helps

From me book:

" The equipotential conductor should be at least greater than half the size of the main earthing conductor. So if the main earthing conductor is 16mm2, the typical main bonding conductor should be 10mm2. This will always satisfy the requirements for PME supply where the supply neutral conductor is not greater than 35mm2

The minimum size permitted is 6mm2, but local electrical suppliers may have their own requirements."

yoshytoshy

Maybe I should ask a different question to get that an easier answer.

If the earth cable used for bonding is 150 meters long ,will 10sq be adequate ?
Will electricity pass through a cable ,regardless of it being connected to an earth rod ?

M cebee

If a main equipotential bond is a long way from MET
then it might have to be oversized.ive used 0.05ohms as a guide for max resistance

yoshytoshy

M cebee wrote: »

If a main equipotential bond is a long way from MET
then it might have to be oversized.ive used 0.05ohms as a guide for max resistance

Thanks M cebee ,I'm just trying to get to grips with the whole thing. I thought it was pretty simple at the beginning to be honest ,earth cable takes the power because it's the only real ground.

If an earth bond is two inches from an earth rod ,how small a cable would take the power ,hypothetically speaking.

EDIT : The reason I want to get to the bottom of this is because people don't appreciate that they have to replace a cable that involves ripping up floors etc. I want to give them a proper answer and not just because it has to meet some book rule.

M cebee

The connection to the rod is the earthing conductor.

Its not a main bond

It the same principle as gas pipe sizing and their is a calculation to match.

Off the top of my head you can run 10 mm2 for 27m and 16mm2 for 43m.
1mm2= 2.7m


L = 0.05Ωx10mm2 ÷ 0.0183 = 27.32 metres
27.32 is the maximum permissible length for a 10mm2 protective conductor

yoshytoshy

gary71 wrote: »

It the same principle as gas pipe sizing and their is a calculation to match.

Off the top of my head you can run 10 mm2 for 27m and 16mm2 for 43m.
1mm2= 2.7m

Thats what I was told by my uncle ,but a guy on the plumbing forum told me I was wrong posting that.

It's not nice telling people they have to change things in their homes ,when you think it's not necessary. I just want to be happy that I know why this has to be done and not be uncertain.

yoshytoshy

M cebee wrote: »

The connection to the rod is the earthing conductor.

Its not a main bond

Sorry ,I just symplified the example.

knighted_1

yoshytoshy wrote: »

Thats what I was told by my uncle ,but a guy on the plumbing forum told me I was wrong posting that.

It's not nice telling people they have to change things in their homes ,when you think it's not necessary. I just want to be happy that I know why this has to be done and not be uncertain.

if your doing gas work installs you should have a copy of IS: 813 to hand -

annex k covers electrical considerations

read k3

this is the only source of reference that is acceptable under rgi rules

yoshytoshy

knighted_1 wrote: »

if your doing gas work installs you should have a copy of IS: 813 to hand -

annex k covers electrical considerations

read k3

this is the only source of reference that is acceptable under rgi rules

There you are big man.

knighted_1

knighted_1 wrote: »

if your doing gas work installs you should have a copy of IS: 813 to hand -

annex k covers electrical considerations

read k3

this is the only source of reference that is acceptable under rgi rules

No, Annex K is for guidance only and directs you to look to ETCI for reference


let down again by the clarity:pac::pac: of our regs

yoshytoshy

I've done some googling myself and found that where an earth rod is used (TT) six square earth is adequate. All other earthing needs to be 10mm2

Only reason for posting this thread is to find out why it's necessary to replace a 6mm earth cable with a 10mm one. Of course running a 10mm earth cable from scratch is the way things are done ,but replacing a 6mm cable is the question.

M cebee

Theyre 3 different things

main bonding

protective conductors

earthing conductor

and theres different rules for each

yoshytoshy

M cebee wrote: »

Theyre 3 different things

main bonding

protective conductors

earthing conductor

and theres different rules for each

Is this the way it is ?

Main bonding is the joining of pipes together ,
Protective conductors are the connections between the fuse board and the main pipe
Earthing conductor is the earth rod.

Edit : Heres the link I found LINK

M cebee

No

yoshytoshy

M ceebee ,in your opinion ,is a 6mm earth cable adequate to bond piping where there is an earth rod as the earthing conductor ?

knighted_1

is 813 does not direct you anywhere for guidence
annex k is informative (for your information) (they are informing you what to do )

k3.2 gas pipework shall be bonded to the main earth terminal at the electrical consumer unit using green/yellow insulated 10mm2 cable

nothing else is accepable

you cant hook in to the existing earth in the house whether it be at the copper cylinder the sink a power socket etc -it states it should have its own earth cable 10mm terminating at the consumer unit - nowhere else

when you signed up to rgi you signed a dec to conform to is 813

yoshytoshy

knighted_1 wrote: »

you cant hook in to the existing earth in the house whether it be at the copper cylinder the sink a power socket etc -it states it should have its own earth cable 10mm terminating at the consumer unit - nowhere else

when you signed up to rgi you signed a dec to conform to is 813

I'm installing gas nearly twenthy years ,I didn't just sign up to rgi my friend.

knighted_1

knighted_1 wrote: »

is 813 does not direct you anywhere for guidence
annex k is informative (for your information) (they are informing you what to do )

From page 70 IS813:

K.1 General


This information is for guidance only and reference shall always be made to the currant edition of the ECTI rules

knighted_1

well rgi is only in existance since 2009 and the is 813 is dated 2002

i was trying to point out the regs ,you asked the original question but are trying to pick holes in the answers you recieved .

20 years ago ,no way were you installing to current regs so you will have to accept that things change . its all in the book nowadays for reference ,which is why on inspection from rgi you must have the is 813 with you .

knighted_1

knighted_1 wrote: »

well rgi is only in existance since 2009 and the is 813 is dated 2002

i was trying to point out the regs ,you asked the original question but are trying to pick holes in the answers you recieved .

20 years ago ,no way were you installing to current regs so you will have to accept that things change . its all in the book nowadays for reference ,which is why on inspection from rgi you must have the is 813 with you .

Lets not be arguing, the Sparkys are watching:D

knighted_1

gary71 wrote: »

From page 70 IS813:

K.1 General


This information is for guidance only and reference shall always be made to the currant edition of the ECTI rules

didnt see that my apologies

does etci tell you to use anything other than 10sq earth on gas pipe ?

knighted_1

knighted_1 wrote: »

didnt see that my apologies

does etci tell you to use anything other than 10sq earth on gas pipe ?

Not that i know of, but I'm the worst kind of gasfitter, one who done a electrical course a few years ago and only remembers bits.
I'm going to have to get my books out know because of bloody yoshytoshy because i can't remember if distance effects the size of cross bonding cable and if I'm getting main bonding and protective conductors mixed up.
But as a guess i would go with 10mm and not the 6mm as it could be a problem if 6mm didn't meet local suppliers regs




The equipotential conductor should be at least greater than half the size of the main earthing conductor. So if the main earthing conductor is 16mm2, the typical main bonding conductor should be 10mm2. This will always satisfy the requirements for PME supply where the supply neutral conductor is not greater than 35mm2

The minimum size permitted is 6mm2, but local electrical suppliers may have their own requirements

knighted_1

knighted_1 wrote: »

.
20 years ago ,no way were you installing to current regs so you will have to accept that things change . its all in the book nowadays for reference ,which is why on inspection from rgi you must have the is 813 with you .

I've been working under gas regs for nearly 25 years, you'd think i would have had it sussed by now:)

yoshytoshy

knighted_1 wrote: »

well rgi is only in existance since 2009 and the is 813 is dated 2002

i was trying to point out the regs ,you asked the original question but are trying to pick holes in the answers you recieved .

20 years ago ,no way were you installing to current regs so you will have to accept that things change . its all in the book nowadays for reference ,which is why on inspection from rgi you must have the is 813 with you .

I've done all my exams and have the book for the regs .Earth bonding was never a part of training , the only items shown were cross bonding at a gas meter in case of a spark when disconnecting.

I check polarity at a boiler to make sure it's wired properly and I'm capable of wiring a heating system ,but thats it. The regs in IS 813 don't make me a sparks ,no matter how well I know them.

M cebee

Minimum 10

at least half size of largest protective conductor

in general no bigger than 70 copper


dont see any mention of a max impedance

but as gary said up to 27m youre below 0.05anyhow

yoshytoshy

Thanks for all been so down to earth ,especially on a bank holiday sunday:)

Bruthal

Its sort of an irony with 10 square bonding, with the terminal on them bonding straps usually used are not up to that size cable.

yoshytoshy

These clips look the part.

Link