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Topic Title: Domestic Electrical Installation Cert
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Created On: 06 September 2005 12:43 PM
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 06 September 2005 12:43 PM
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pm70511

Posts: 118
Joined: 07 March 2005

All,

When completing a Domestic Electrical Installation Cert., for installing a supply to a detached garage. Would you put the TT arranged garage, or the PME arranged house supplying the garage in the section of the cert. marked up particulars, system type etc.

Not forgetting that the garage has been converted to a TT supply (due to the house being PME TN-C-S) and therefore relies on an earth rod for main earth connection (the PME ends where the SWA gland is made off just before the plastic CCU in garage.

Also if not in the particulars and system type where would you record the Ra value for the earth rod?

Cheers P

-------------------------
Kind Regards

PM70511

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 06 September 2005 06:46 PM
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pm70511

Posts: 118
Joined: 07 March 2005

I can't believe there isn't anybody out there that can't answer this question for me?

Cheers P

-------------------------
Kind Regards

PM70511

Why do kamikaze pilots ware crash helmets?????
How do you know the fridge light goes off when the door is closed?????
 06 September 2005 07:42 PM
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normcall

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OK, how about it's a TT suply and complete accordingly.

-------------------------
Norman
 06 September 2005 07:43 PM
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patrickburton

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Hello pm, The EIC form provides for your Description & Extent of the Installation. Followed by Supply Characteristics & Earthing Arrangements (TN-C-S in your case). Followed by Particulars of the Installation Referred to in the Certificate, in which you record the Electrode Resistance, Location & Type etc. Should you wish to expand on this, for the customer's edification, then you can set it in Plain English in the section for Comments on Existing Installation. Kind regards, Pb
 06 September 2005 07:51 PM
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pm70511

Posts: 118
Joined: 07 March 2005

Gents,

Thanks for your comments, you can see how I come to question this point now cant you. What with you both having different ideas about the supply arrangement, one saying TT and the other saying TN-C-S ?????

Cheers P.

-------------------------
Kind Regards

PM70511

Why do kamikaze pilots ware crash helmets?????
How do you know the fridge light goes off when the door is closed?????
 06 September 2005 08:15 PM
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John Peckham

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You cannot put the details of the earh electrode in the details of supply at the origin because the supply at the origin is TNCS.

These in my humble view leaves 2 options.


1. Put the garage installtion on a continuiation sheet and hand write the information on this sheet. OR

2. Produce a separate certificate for the garage installation.

If you are using the NICEIC forms they are not geared up for this situation so you will have to adapt or treat the garage as a stand alone installation.

Regards


John Peckham

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 06 September 2005 08:30 PM
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pm70511

Posts: 118
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John,

I am quite happy to produce a separate sheet for the garage; however this then suggests that i either have to do another sheet just for the supply to the garage??? Or also on this sheet conduct a complete second inspection of the whole house!

What I am trying to inspect and test is the garage installation but not omitting the supply to it????

Still confused

P

-------------------------
Kind Regards

PM70511

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 06 September 2005 08:35 PM
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Igot3ears

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pm70511, your certificate should cover your new installation at it's origin. If you've installed the supply cable to the garage then your installation starts from where you connected to in the house so it's tnc-s. If your new work starts at the garage consumer-unit then your certificate should be TT. Sounds to me like you have a tnc-s supply with a sub-main to the garage. Like John Peckham says, you'll need to use continuation sheets for the garage.

3ears
 06 September 2005 08:39 PM
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John Peckham

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Put the supply to the garage on the house test results sheet. I assume it is fed from the consumer unit? You can measure the Zs at the garage end for the Zs box.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 06 September 2005 08:41 PM
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pm70511

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Igot3ears,

Are you saying that I now have to cert the house on one sheet and add a continuation sheet for the garage and do double the work?????

I need to crystal on this!

Thanks PM70511

-------------------------
Kind Regards

PM70511

Why do kamikaze pilots ware crash helmets?????
How do you know the fridge light goes off when the door is closed?????
 06 September 2005 08:47 PM
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Igot3ears

Posts: 359
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No. Assuming you've connected into the existing consumer-unit then you'll have one circuit on your main certificate (the sub-main to the garage). You then need 2 continuation sheets for the garage circuits - one for circuit shedule and one for test results.

3ears
 06 September 2005 10:57 PM
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deleted_stevecf

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The NICEIC domestic electrical installation certificate has a line at the top of the circuit details which says

To be completed only where this consumer unit is remote from the origin of the installation. Record details of the circuit supplying this consumer unit in the bold box
 06 September 2005 11:35 PM
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patrickburton

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pm, I refer you to my earlier post: There is no need for continuation sheets (other than test results etc) There is adequate provision on the standard BS7671 EIC form. Otherwise this situation - that some are treating as unique, would have come to light years ago.
Having described the EXTENT of the installation and ticked the box, either addition or alteration, then there can be no doubt that you refer to the garage only. Then the section SUPPLY CHARACTERISTICS & EARTHING ARRANGEMENTS: TN-C, TN-S, TN-C-S, TT etc: Your supply is TN-C-S.
Followed by a COMPLETELY SEPARATE SECTION for PARTICULARS REFERRED TO IN THE CERTIFICATE. ie: THE GARAGE.
Means of earthing: tick either SUPPLIER'S FACILITY or EARTH ELECTRODE. You would not be asked to tick electrode if you had already ticked TT in the previous section for example. My earlier post made no mention of putting "details of earth electrode in the details of supply at the origin" and I'm surprised at such careless reading. I reiterate, you have the opportunity to clearly explain the reason for two earthing methods, in the final section: Comments on Existing Installation. Kind regards, Pb
 06 September 2005 11:35 PM
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ebee

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quote:

Originally posted by: johnpeckham
You cannot put the details of the earh electrode in the details of supply at the origin because the supply at the origin is TNCS.

These in my humble view leaves 2 options.


1. Put the garage installtion on a continuiation sheet and hand write the information on this sheet. OR

2. Produce a separate certificate for the garage installation.

If you are using the NICEIC forms they are not geared up for this situation so you will have to adapt or treat the garage as a stand alone installation.

Regards


John Peckham


John ,
in my opinion,

TNC-S from house to garage on one EIC garage Zs being recorded, this them becomes the Ze for garage CU on a seperate EIc recording TT as its method.
Am I wrong?
This question I have asked many times with no definative answer so I would welcome feedback



-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 07 September 2005 09:16 AM
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John Peckham

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Ebee

No not in this case as the earh is from the electrode as the SWA is insulated from the garage extension. The Ze for the garage is the Ra of the earth electrode.

In other case the Ze is only to be found at the origin of the supply as it is the external impedance. If you have distribution boards not connected to the origin the impedance is Zs or sometimes written Zdb. If you look at the top of the NICEIC type sheets you will see you only record there are boxes to record Zs of the board where the board is not connected to the origin of the supply.

Regards


John Peckham

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 07 September 2005 11:54 AM
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deleted_beenthere

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I still maintain that making a garage a TT system is old hat and stand by that it is not a IEE reg but an OLD supply reg I know which earth I would put my life on
 07 September 2005 12:54 PM
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pm70511

Posts: 118
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beenthere,

Not to complicate matters, but if like in this case your garage was supplying a hot tub, then i would hope you would us the TT method

Even though you cant achieve as low impedance with rod as a PME supply. I would still be happier sitting in a tub with a TT arrangement, at least you know in a fault condition, where the TT is concerned you are never going to get an external earth fault current stuck up your backside.

Think about this one it needs some thought!

Cheers PM

-------------------------
Kind Regards

PM70511

Why do kamikaze pilots ware crash helmets?????
How do you know the fridge light goes off when the door is closed?????
 07 September 2005 01:25 PM
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John Peckham

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If you are going to supply a hot tub from a TNCS supply then you should definitly convert to TT for the supply. Whilst the risk is low in a garage supplied with TNCS the risk to persons using a hot tub is much higher. Large areas of exposed skin, wet feet and direct contact with the general mass of earth I would say substantially increase the risk. I would have a 30mA RCD protecting the suppl;ly whatever the earth electrode resistance. GN5 says swimming pool supplies should not be TNCS and I would say a hot tub is a mini swimming pool.


Regards


John Peckham

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 07 September 2005 02:05 PM
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pm70511

Posts: 118
Joined: 07 March 2005

John,

Absolutely spot on my thoughts entirely and yes the garage is fully protected by an RCD

Cheers PM

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Kind Regards

PM70511

Why do kamikaze pilots ware crash helmets?????
How do you know the fridge light goes off when the door is closed?????
 07 September 2005 07:04 PM
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ebee

Posts: 5672
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quote:

Originally posted by: johnpeckham
Ebee

No not in this case as the earh is from the electrode as the SWA is insulated from the garage extension. The Ze for the garage is the Ra of the earth electrode.

In other case the Ze is only to be found at the origin of the supply as it is the external impedance. If you have distribution boards not connected to the origin the impedance is Zs or sometimes written Zdb. If you look at the top of the NICEIC type sheets you will see you only record there are boxes to record Zs of the board where the board is not connected to the origin of the supply.

Regards


John Peckham


Sorry John that was a silly slip yes of course the Ze for the (TT) garage would be Ra what on earth was I thinking of?

The point I should have been asking say in a TNS system origin of supply Ze =(R1 + R2) gives Zs to dist board , does this Zs at the dist board them become its local Ze (external to that dist board itself) and be used with R1/R2 calculations to feed further sub circuits to arrive at Zs at points of untilisation (some of which might just be another dist board ad infinitum).
I must admit I like the term Zdb as it makes clear what is going on.
But a seperate EIC for each board or not that was essentially my question (well it`s what I meant to ask).
Regards,
ebee





-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
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