Supply to garage.

[Gavin John Hyde]

For car charger I would go for a zappi or pod point. Neither requires an earth rod but importantly both have ct clamp functions to monitor the load in the property and garage to protect the fuses. It will throttle the charger up or down according to capacity in the property. When there is little demand the charger can pull the full 32 Amps. If other things are in use it will charge at a lower rate.

 

[Edward67]

For car charger I would go for a zappi or pod point. Neither requires an earth rod but importantly both have ct clamp functions to monitor the load in the property and garage to protect the fuses. It will throttle the charger up or down according to capacity in the property. When there is little demand the charger can pull the full 32 Amps. If other things are in use it will charge at a lower rate.

Thx for advice. Sorry for slow reply.

 

[TJ Anderson]

OP, Sizing cables is down to factors other than ability to teminate!! Seriously, confirm exactly what he is having and how he will use it, then work out a realistic design current. It may save a few quid too.

 

[goasis]

This all seems a bit crazily thought out, do you always choose your cable sizes based on how easily it will be to terminate them?!

 

[TJ Anderson]

Hi thanks for reply.
I don't fully understand your isolator point. The current tails are 15 hence they are on the isolator seen in the picture. They do not require fused switch? So why would my swa require one.

I see your point but not entirely sure I agree otherwise all meter tails would need one wouldn't they?

Hope you respond with your thoughts.

Thankyou.

I just read this. I genuinely think you should decline this job.

 

[Edward67]

This all seems a bit crazily thought out, do you always choose your cable sizes based on how easily it will be to terminate them?!

No not at all. But when your only option is the meter cupboard space you start to have issues. My concern was for future car charging capacity when he has two cars but since having looked at the xlpe cable I will go for 16mm. 10mm would most probably be ok but why ---- about for 20 pound considering the 12 meters of digging.
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Nonsense, having a concrete floor does not require you to install a TT system.

Everyone is happy to criticise so I will respond. This is direct from stroma please read Dave sparks.


If the remote building has a concrete earth floor, or conductive floor, or the building is of metal construction or metal outside skin, the shock risk is increased. It’s therefore recommended that the remote building has a TT earthing system.

That is why I will TT it.

 

[TJ Anderson]

No not at all. But when your only option is the meter cupboard space you start to have issues. My concern was for future car charging capacity when he has two cars but since having looked at the xlpe cable I will go for 16mm. 10mm would most probably be ok but why ---- about for 20 pound considering the 12 meters of digging.
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Everyone is happy to criticise so I will respond. This is direct from stroma please read Dave sparks.


If the remote building has a concrete earth floor, or conductive floor, or the building is of metal construction or metal outside skin, the shock risk is increased. It’s therefore recommended that the remote building has a TT earthing system.

That is why I will TT it.

You only need to prove if it is extraneous. If it is not then you have nothing to bond.

 

[Edward67]

I just read this. I genuinely think you should decline this job.

TJ Anderson thanks for response. My response you highlighted doesn't read well. I will try to explain better for discussion. That's what it is discussion not criticism.
When meter tails are over 3m an isolator is normally needed to satisfy the dno.
If the tails were split with say swa cable and a neat way was found to terminate the swa without the need of a fused switch then what is the difference between the new swa tails and the existing house tails? If they the same rating?
The difference the swa is actually better protected than the original tails that run for 15 meters through the house.
The discussion was if the new tails absolutely have to have a fused switch then why is just an isolator acceptable for every other property in the uk with meter tails over 3m.
I will be using a fused switch, I will be changing cable size to xlpe because of its increased rating I will be TTing the system.
The reason for the TT is its safer.

I can speck the install 100 percent because he doesnt know how many chargers he wants in the future. Most probably 2 but not ruled out more.
I hold my hands up to not knowing the true capabilities of xlpe cable over standard swa but I have now been educated

Discussion forum not criticism forum. People come on for help and advice in improving installs not to be picked apart otherwise what's the point.

 

[pc1966]

The discussion was if the new tails absolutely have to have a fused switch then why is just an isolator acceptable for every other property in the uk with meter tails over 3m.

The way I have always seen the regulations interpreted is you (i.e. the designer) has to provide the switching & OCPD for cables longer than 3m.

Obviously if your cable is rated below the DNO fuse (e.g. sub-main to a garage CU in 6mm or whatever) then it is essential that you include the appropriate fuse/breaker.

Now from a simple engineering point of view there is no reason why you should add a 2nd 100A fuse immediately after the DNO fuse as you will have no selectivity. But from an ownership and legislation point of view the DNO side is separate and distinct from the installation you are designing. Theoretically they can change the ratings and/or the OCPD to suit whatever is needed for protecting their network.

So some might feel that only an isolator is needed if the long tails are adequately protected from overload by the DNO's biggest fuse option, but I have always seen it interpreted as the installation should be designed to have OCPD under your control.

 

[Edward67]

The way I have always seen the regulations interpreted is you (i.e. the designer) has to provide the switching & OCPD for cables longer than 3m.

Obviously if your cable is rated below the DNO fuse then it is essential that you include the appropriate fuse/breaker.

Now from a simple engineering point of view there is no reason why you should add a 2nd 100A fuse immediately after the DNO fuse as you will have no selectivity. But from an ownership and legislation point of view the DNO side is separate and distinct from the installation you are designing. Theoretically they can change the ratings and/or the OCPD to suit whatever is needed for protecting their network.

So some might feel that only an isolator is needed if the cables are adequately protected from overload by the DNO's biggest fuse option, but I have always seen it interpreted as the installation should be designed to have OCPD under your control.

Thankyou now that is what I call a well constructured reply. Explains the point very clearly and explains my question.

 

[TJ Anderson]

TJ Anderson thanks for response. My response you highlighted doesn't read well. I will try to explain better for discussion. That's what it is discussion not criticism.
When meter tails are over 3m an isolator is normally needed to satisfy the dno.
If the tails were split with say swa cable and a neat way was found to terminate the swa without the need of a fused switch then what is the difference between the new swa tails and the existing house tails? If they the same rating?
The difference the swa is actually better protected than the original tails that run for 15 meters through the house.
The discussion was if the new tails absolutely have to have a fused switch then why is just an isolator acceptable for every other property in the uk with meter tails over 3m.
I will be using a fused switch, I will be changing cable size to xlpe because of its increased rating I will be TTing the system.
The reason for the TT is its safer.

I can speck the install 100 percent because he doesnt know how many chargers he wants in the future. Most probably 2 but not ruled out more.
I hold my hands up to not knowing the true capabilities of xlpe cable over standard swa but I have now been educated

Discussion forum not criticism forum. People come on for help and advice in improving installs not to be picked apart otherwise what's the point.

Thank you. I apologise for my outrageous behaviour.

Absolutely......Let's continue our discussion.....

I am pleased to hear about your revelation regarding XLPE SWA. Amazing stuff it is. Can you educate me as to the equipment you are now designing to run at 90 Degrees Celsius? I have never got to do that in my limited electrical dabblings as I struggled to find suitable reasonably priced items for garages and garden shed installs etc

Why is TT safer here, we only have that PME at work. Am I in danger, I really don't understand??
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Thankyou now that is what I call a well constructured reply. Explains the point very clearly and explains my question.

Again, I'm terribly sorry and I'd like to add the irony of this was not lost on me.

 

[Edward67]

Thank you. I apologise for my outrageous behaviour.

Absolutely......Let's continue our discussion.....

I am pleased to hear to hear about your revelation regarding XLPE SWA. Can you educate me as to the equipment you are now designing to run at 90 Degrees Celsius? I have never got to do that in my limited electrical dabblings as I struggled to find suitable reasonably priced items for garages and garden shed installs etc

Why is TT safer here, we only have that PME earth thing at work. Am I in danger, I really don't understand??

A

Thank you. I apologise for my outrageous behaviour.

Absolutely......Let's continue our discussion.....

I am pleased to hear about your revelation regarding XLPE SWA. Amazing stuff it is. Can you educate me as to the equipment you are now designing to run at 90 Degrees Celsius? I have never got to do that in my limited electrical dabblings as I struggled to find suitable reasonably priced items for garages and garden shed installs etc

Why is TT safer here, we only have that PME at work. Am I in danger, I really don't understand??

Really helpful king of person. Thanks.
Two quotes. You don't know what you don't know.
And don't judge someone on their worst day to you on your best.

Now rather than criticising either help my understanding or go away. You hold the 2396 so you are perfectly capable of explaining.

I would try and explain my reasoning but sure you would just RIP it apart with no explanation.

I don't know your background and will not guess but I often find the best designers are the worst installers and the best installers are the worse designers.

Goodnight.

 

[richy3333]

For fear of this turning into a keyboard fight and getting moderated i would suggest to the OP (and am sorry if this upsets you as it is meant as positive criticism), but having read 2 pages of posts I do believe the job is beyond you; certainly from a design perspective at any rate.

Your original post details a very standard type of installation that we as sparkies often do, but your questions and comments do indicate it is something you have possibly not yet tackled before. Can you not get a more experienced contractor to let you shadow them and see how it’s done? Maybe someone from the forum can help?

 

[radiohead]

It has struck me over time on this forum that a simple supply to an outbuilding/garage/shed often seems to become a monumentally complex issue for no apparent reason.

 

[Edward67]

For fear of this turning into a keyboard fight and getting moderated i would suggest to the OP (and am sorry if this upsets you as it is meant as positive criticism), but having read 2 pages of posts I do believe the job is beyond you; certainly from a design perspective at any rate.

Your original post details a very standard type of installation that we as sparkies often do, but your questions and comments do indicate it is something you have possibly not yet tackled before. Can you not get a more experienced contractor to let you shadow them and see how it’s done? Maybe someone from the forum can help?

Was having bad day yesterday. Little.one went to hospital with peanut reaction so will take it o the chin.
Mr TJAnderson has opened my eyes to looking at it from a different perspective and he is entirely correct in his xlpe comment on cable selection.
I have got another very experienced contractor to aid in this but wanted to explore all options in open environment.
I think the forum would a better place if instead of people just saying why or wouldn't do that they explain their own view and reasoning as in with pme. Which has been discussed numerous times on many forums and always results in differing opinions.
Any more information on exporting pme that is concrete and not a personal view would be appreciated.

 

[7029 dave]

It has struck me over time on this forum that a simple supply to an outbuilding/garage/shed often seems to become a monumentally complex issue for no apparent reason.

Might have something to do with special locations

 

[pc1966]

Also it is not a "standard circuit" that you can just look in the OSG table for a yes/no based on load, length and CSA.

There is the special location side - the whole CPC from PME in another location with or without extraneous conductive parts bonding to worry about.

Then you have the simple circuit, say a couple of sockets and FCU for lights fed from house CU slot, versus a sub-main to a 2nd CU/DB and the whole OCPD/RCD selectivity arguments that go with planning that.

 

[richy3333]

@Edward67 hope the little dude is ok, really worrying when as a dad you can’t fix it and have to trust others.

The forum works best (imho) when someone says whom they are, their experience and then ask for help, having shown their calculations and described what they are to achieve or drawn a diagram etc. Part of the problem is that there are too many DIYers on here pretending to know something when they clearly don’t (I’m in no way suggesting that’s you).

I hope you keep posting questions ?

 

[Edward67]

@Edward67 hope the little dude is ok, really worrying when as a dad you can’t fix it and have to trust others.

The forum works best (imho) when someone says whom they are, their experience and then ask for help, having shown their calculations and described what they are to achieve or drawn a diagram etc. Part of the problem is that there are too many DIYers on here pretending to know something when they clearly don’t (I’m in no way suggesting that’s you).

I hope you keep posting questions ?

Ok will attempt to post with more depth in future.

 

[radiohead]

Any more information on exporting pme that is concrete and not a personal view would be appreciated.

You are not 'exporting PME', you are simply extending an existing earthing system.
I've never ever heard anyone say they are 'exporting TNS....or TT'.

Might have something to do with special locations

It's not a special location.