Im looking at installing an electric heater in my grandmothers house but it requires a three phase supply..

I spoke to her energy supplier (scottish power) and they tell me that if I go ahead and install the new heater with the relevant wiring to the meter, they will then come and change the meter for a three phase unit and all will be working fine...

They say they can do that for free....


But..im sceptical, surley the supply from the substation is only single phase?...so wont they have to do more than just install a new meter?

urgh...so complicated!

All 3 phases run down the street, with seperate phases being sent into alternating houses.

They would need to add in the extra cables form the supply down the street as well I would have thought.

David

Get it in writing before you commit yourself!
I am an electrician and I have my doubts too about what you have been told.

Should get 3 phase to the street, but they normally charge to bring it into a property. IIRC

As David has said.

They will need to dig up the cable to put in 3 phase unless its overhead cable, then it's a bit easier.

They will most likely want to charge the 3 phase industrial standing charge as well.

3 phase heater that must be some bit of kit.

Mike

its not free normally, so get it in writing first!

Im very curious about what sort of 3 phase heater your granny needs?!

Note that you (personally) are no longer allowed to install anything electrical other than maybe replace a plug point. ie, if it requires wiring you can't do it unless you are qualified electrician. (thanks Brussels)

Be easier to rewire your heater to single phase

You can add in a spur from an existing point, but thats about as far as it goes i think....

Exactly how they are supposed to tell if you did it yourself is beyond me anyway.

David

i believe you cannot add a spur. By that i mean you actually can, like most other work, but you would have to notify your LABC and get the work inspected by the buildings inspector.

However, if unqualified, you are not likely to do it to a standard that would pass an inspection anyway.

Scroll down this for exhaustive details:

http://www.opsi.gov.uk/si/si2004/20043210.htm

Surely this:

quote:

---

DESCRIPTIONS OF WORK WHERE NO BUILDING NOTICE OR DEPOSIT OF FULL PLANS REQUIRED


1. Work consisting of -

(a) replacing any socket-outlet, control switch or ceiling rose;

(b) replacing a damaged cable for a single circuit only;

(c) re-fixing or replacing enclosures of existing installation components, where the circuit protective measures are unaffected;

(d) providing mechanical protection to an existing fixed installation, where the circuit protective measures and current carrying capacity of conductors are unaffected by the increased thermal insulation.

2. Work which -

(a) is not in a kitchen, or a special location,

(b) does not involve work on a special installation, and

(c) consists of -

(i) adding light fittings and switches to an existing circuit;

(ii) adding socket outlets and fused spurs to an existing ring or radial circuit; or

(iii) installing or upgrading main or supplementary equipotential bonding.

3. Work on -

(a) telephone wiring or extra-low voltage wiring for the purposes of communications, information technology, signalling, control and similar purposes, where the wiring is not in a special location;

(b) equipment associated with the wiring referred to in sub-paragraph (a).

4. For the purposes of this Schedule -

"kitchen" means a room or part of a room which contains a sink and food preparation facilities;

"special installation" means an electric floor or ceiling heating system, a garden lighting or electric power installation, an electricity generator, or an extra-low voltage lighting system which is not a pre-assembled lighting set bearing the CE marking referred to in regulation 9 of the Electrical Equipment (Safety) Regulations 1994[14]; and

"special location" means a location within the limits of the relevant zones specified for a bath, a shower, a swimming or paddling pool or a hot air sauna in the Wiring Regulations, sixteenth edition, published by the Institution of Electrical Engineers and the British Standards Institution as BS 7671: 2001 and incorporating amendments 1 and 2."

---

Its ok...its a monster job so I will be looking for an electrician...

The heater is a 28Kw air source heatpump which requires a three phase supply to run its twin compressors...

Its either use the 28Kw on three phase or use a pair of 11Kw units on single phase....its going to be cheaper to run a tripple phase unit IMHO...

Is there anyone other than scottish power that I could ask about this because they are so hard to get hold of and I dont think they know what they are talking about!

Chears.

damn, proven wrong by my own link! I stand corrected.

David, I think that;"DESCRIPTIONS OF WORK WHERE NO BUILDING NOTICE OR DEPOSIT OF FULL PLANS REQUIRED " means just that. I would expect any electrical installation work to require a completion/ part P inspection certificate, issued by the spark doing the work or that nice inspector chappy from the council, who will gouge you for about £350. A cheaky b@stard that quoted a friend of mine £6,500 for what should be two days work, also qouted him £490 for certifying his own work!
Nice new avatar by the way. About time we saw the flip side.

[Edited on 23/3/07 by Confused but excited.]