Electrical conection to a boiler? help!


Postby trainefficient » Tue Sep 01, 2009 2:47 pm

Installing boilers has become a two trade installation with the Part P unless you are trained. The electrical conection from the boiler needs to come from a fused double pole isolator (spur). I have noticed that there are installations where the use of a plug is used direct into a unswitch shuttered socket outlet. I find this way is much better as the
Mains-earth continuity,
Short circuit check
and Polarity
can be tested easily using a Multimeter. If the installation was from a spur then you would have to off the electrics of the house in that area and take the wire of the spur in the wall then test, VERY TIME CONSUMING but needs to be done !.

Some boilers state in there instruction manuals that unswitch shuttered socket outlet can be used.

I want to know if this method can be used for all Domestic boilers even if it doesn't say in the manufatures instructions as it does comply with Electrical regulations?
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Postby kbrownie » Tue Sep 01, 2009 5:00 pm

The requirements BS7671:2008 (electrician bible) will instruct you to hard wire boilers to Switched Fused connection Unit but also with instruct you to follow by manufacturers Instruction.
I find it strange that recommendation are made for an unswitched socket outlet.
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Postby trainefficient » Wed Sep 02, 2009 10:43 am

I have been told the benifit of an unswitched socket outlet would be that all suspected electrical current is eleminated by simply taking the plug out.
A switched fused connection could have a suspected current although this is rare to me. I did come across one boiler change installation i did and found the neutral wire loose, it was basically just sitting in the hole due to tention but not screwed down.

At the end of the day we want to do what the BS and Regs tell us and my question on this topic is due to have been told that it is acceptable by an experienced engineer/teacher. I have come across a boiler manufacturer after calling them if it would be accepted and explaining the benifits they said it was ok to do.

Is there anywhere in the BS7671 where an unswitched socket outlet is acceptable?
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Postby kbrownie » Wed Sep 02, 2009 9:37 pm

Regarding permanently connected equipment, which I'd consider a boiler to be as it supplys hot water to taps and central heating.
BS7671:2008 is as always open to interpreation.
Requirement 537.5.1 touch on this
537.5.1.3 In general, all current-using equipment requiring control shall be controlled by an appropriate functional swithing device.
The on-site guide
8.2.5 reffers to this requirement and explains it thus:
Permanently connected equipment should be locally protected by a fuse complying with BS 1362 of a rating not exceeding 13A or by a circuit breaker of rating not exceeding 16A and should be controlled by a switch, where needed. A separate switch is not required if the circuit-breaker is to be used as a switch.
I don't get the reasoning behind using a socket outlet rather than SFCU,
you find boilers tucked away in bathrooms where socket-outlets are very restricted, so likely that it would not be feasible to connect a boiler via plug top and socket.
I don't know if I'm helping you any. As I stated in earlier post, I'd use flex conncetion between SFCU and boiler or manufacturers instruction.
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Postby trainefficient » Thu Sep 03, 2009 3:13 pm

I agree with you that in a bathroom or near water conections this method should not be used.

I understand the preferred method by you and many engineers.

Its true to say that a boiler is regarded permanently connected equipment and this should answer my question of a unswitched socket conection being used.

I would love to know how engineers are justifying the unswitched socket. I will locate the engineer/teacher who told me about this to show me evidence how he justifies these conections.

i appreciate your replies, thanks.
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Postby kbrownie » Fri Sep 04, 2009 5:18 pm

I too would be interested and which relevant standard they are using.
So when you find out drop a line.
KB
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Postby htg engineer » Sat Sep 05, 2009 7:41 pm

There's alos a topic in the Gas Fitting Forum on this matter. If kbrownie cares to take a look and offer advice.


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Postby sparx » Sun Sep 06, 2009 9:32 am

hi,
I was told by a local gas fitter that it was advice from 'Corgi/british gas' that a plug could be removed and put inside a lockable enclosure to ensure it remains dead during work.
I have seen one such plastic box (yellow).
However most FCU's, if you remove the fuse, can be fitted with a small padlock anyway , but can still be switched on which could be a problem if connected reverse polarity as boiler would not work but would still be 'live'.
I am not aware of anything in regs to prevent use of socket outlet, but I believe it should be unswitched or double pole switched for reason of polarity above.
regards Sparx
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